Ata 34 2 03 01
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Boeing 747-400 Training manual
engineering & maintenance Training E & M
ATA-34 NAVIGATION (PART 2) Config: ALL
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engineering & maintenance Training E & M
Config: ALL
Boeing 747-400 Training manual
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engineering & maintenance Training E & M
NAVIGATION TCAS
Boeing 747-400 Avionics
TRAFFIC ALERT AND COLLISION AVOIDANCE SYSTEM (TCAS) INTRODUCTION ...................................................................... 2
TCAS II - COMPUTER TRACKING SCENARIO ............................ 32 TCAS II - PRINCIPLES ................................................................... 35
TCAS II ........................................................................................... 5 TCAS II - COMPONENT LOCATIONS ........................................... 8
TCAS II - CONTROL AND DISPLAY MESSAGES ......................... 38 TCAS II - NAVIGATION DISPLAYS .................................................. 40
TCAS II COMPONENT LOCATIONS - FLIGHT DECK ................... 10 TCAS II - INTERFACES-1 .............................................................. 15
TCAS II - PRIMARY FLIGHT DISPLAY ........................................... 44 TCAS II - AURAL MESSAGES ....................................................... 47
TCAS II - INTERFACES-2 .............................................................. 19 TCAS II - COMPUTER ................................................................... 22
TCAS II - SYSTEM INPUTS/OUTPUTS ......................................... 53 TCAS II - MICROPROCESSOR OPERATION .............................. 57
TCAS II - ATC/TCAS CONTROL PANEL ....................................... 24 TCAS II - EFIS CONTROL PANEL ................................................. 26
MANUAL SELF TEST ..................................................................... 60 TCAS II - CMC GROUND TEST..................................................... 62
TCAS II - DIRECTIONAL ANTENNA ............................................... 28 TCAS II - BASIC OPERATION ....................................................... 30
TCAS II - FLIGHT DECK EFFECTS AND CMC MESSAGES ........ 64
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NAVIGATION TCAS
TRAFFIC ALERT AND COLLISION AVOIDANCE SYSTEM (TCAS) - INTRODUCTION
General
TCAS II
The Traffic Alert and Collision Avoidance System (TCAS) alerts the flight crew of potential conflicts with other airplanes in the same area. TCAS tracks these other airplanes or intruders, if equipped with a Air Traffic Control Radar Beacon System (ATCRBS), or a Mode S ATC transponder.
TCAS II is the system installed on 747-400 airplanes. It supplies both visual and aural advisories to the flight crew. Both TAs and RAs are generated by this system. All commercial airlines and some general aviation airplanes will be equipped with this system.
TCAS provides two types of collision avoidance alerts they are:
TCAS III
- Traffic advisory (TA) - Resolution advisory (RA)
TCAS III is still under development. When finished, it will have all the capabilites of TCAS II, plus the ability to provide horizontal collision avoidance maneuvers.
A TA shows the relative position of any intruder airplanes. An RA shows a vertical maneuver to avoid a possible airplane collision.
TCAS I TCAS I is the system intended for use on small commuter or general aviation airplanes. TCAS I supplies proximity traffic advisories (TAs), but does not produce resolution advisories (RAs).
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NAVIGATION TCAS
Boeing 747-400 Avionics
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NAVIGATION TCAS
TCAS II
General
Component Description
The TCAS II components are the:
The TCAS II system is composed of only airborne components. The TCAS computer is the main component of the system and communicates with both intruder airplane and on-board ATC transponders.
- TCAS computer - Dual directional TCAS antennas - ATC/TCAS control panel Components that interface with the TCAS II are the: - L & R ATC mode S transponder - L & R radio altimeter (RA) - R, C, or L inertial reference units (IRU’s) - Ground proximity warning computer (GPWC) - Modularized avionics and warning electronics assembly (MAWEA) - Integrated display system (IDS) - L & R central maintenance computers (CMC’s) - L & R distance measurement equipment (DME’s) - Data management unit (DMU) - Landing gear module - Air/ground relay
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NAVIGATION TCAS
Boeing 747-400 Avionics
Component Description (cont) The TCAS II computer works like an ATC ground station interrogator. It transmits pulse coded interrogations at 1030 MHz on both a top and bottom directional antenna. The TCAS II computer sends a suppression pulse to both ATC transponders and to both DME’s upon rf transmission. TCAS antenna replies are received on 1090 MHz. The TCAS II computer analyzes all inputs and computes the position of all intruders and any possible collision courses. The navigation displays (NDs) show the intruder symbols in different shapes and colors. These symbols show the intruder’s priority, position, relative altitude, along with a vertical speed arrow. Collision avoidance flight cues show on the PFD attitude display. The TCAS II computer sends aural collision avoidance messages through the MAWEA to the aural warning speakers. The CMC monitors the TCAS II status and starts the TCAS II ground test.
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NAVIGATION TCAS
Boeing 747-400 Avionics
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NAVIGATION TCAS
Boeing 747-400 Avionics
TCAS II - COMPONENT LOCATIONS
The TCAS II components are the: - TCAS II computer - Top directional TCAS II antenna - Bottom directional TCAS II antenna
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NAVIGATION TCAS
Boeing 747-400 Avionics
TCAS II COMPONENT LOCATIONS - FLIGHT DECK
The TCAS II components in the flight deck are the: - ATC/TCAS control panel - TCAS circuit breaker Components in the flight deck that interface with TCAS II are the: - Left inboard and outboard IDU - Right inboard and outboard IDU - Lower IDU - Left EFIS control panel - Right EFIS control panel
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Boeing 747-400 Avionics
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NAVIGATION TCAS
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NAVIGATION TCAS
TCAS II - INTERFACES-1
Power
GPWC Inputs
The TCAS II computer gets 115 volts ac from ac bus 3.
The GPWC sends three discretes to the TCAS computer. These discretes inhibit intruder resolution advisories during windshear, ground proximity warning or ground proximity alert conditions.
Radio Altimeter Inputs The TCAS II computer gets radio altimeter (RA) data from the left and right RAs. The TCAS II processor uses RA data to: - Set sensitivity levels - Calculate intruder advisories
Landing Gear Control Module Input The TCAS II computer uses the landing gear input discrete to make the bottom TCAS antenna perform as an omnidirectional antenna when the landing gear is down.
Inertial Reference Unit Inputs
Air/Ground Relay Input
The TCAS II computer gets inertial reference unit (IRU) data from the IRU selected by the first officer. The TCAS II computer uses IRU magnetic heading to smooth the intruder display on the ND. Pitch and roll are not currently used by TCAS but are reserved for future TCAS development.
The TCAS II computer uses the air/ground relay discrete to prevent TCAS test in the air. The air/ground discrete increments flight legs in the TCAS fault history when the CMC fails.
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NAVIGATION TCAS
Boeing 747-400 Avionics
Program Pin Inputs Four strapping type program pins set: - The airplane altitude limit of 48 thousand feet for RA performance calculations (no climb or increase climb cues when at this altitude) - A self-test inhibit function to prevent self-test in air - The audio level of voice outputs
EIU Inputs The left and center EIUs send resolution advisory RA display status #1 discrete and the right EIU sends a RA display status #2 discrete to the TCAS processor. These discretes provide the TCAS with the IDU display capability. When the Captain and First Officer’s PFD is unable to display RA data, both RA #1 and RA #2 are set from a ground to an open. TCAS FAIL message shows on the ND’s when in the TA/RA mode. Switch to the TA only mode to allow TCAS to continue to display TA data.
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NAVIGATION TCAS
TCAS II - INTERFACES-2
ATC Inputs/Outputs
CMC Inputs/Outputs
The TCAS II computer gets ATC and control data from the ATC/ TCAS control panel through the selected left or right ATC. The ATC provides the TCAS processor with:
The TCAS II computer gets CMC data from the left CMC. The CMC provides the TCAS processor with a ground test start cue. The TCAS computer sends the CMC’s TCAS status data.
- TCAS mode selection (TA only, or TA/RA) - Uncorrected baro altitude - Airplane identification code - Maximum airspeed The TCAS computer sends coordination data to the active ATC transponder on a high speed ARINC 429 data bus. The on-board transponder is a part of the data link system when TCAS is working with other TCAS equipped airplanes.
TCAS II Voice Outputs TCAS II sends aural alert annunciations to the MAWEA to alert the flight crew to TAs and RAs. These signals go to both the left and right aural synthesizer cards.
Suppression Inputs/Outputs The TCAS II computer gets a suppression pulse when the selected ATC or the DMEs transmit. This suppression signal turns off the TCAS receiver for the suppression period. When TCAS transmits, it sends a suppression pulse to the selected ATC and the DMEs.
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NAVIGATION TCAS
Boeing 747-400 Avionics
IDU Display Outputs IDU display data is sent out on ARINC 429 data buses to the PFDs and NDs, the DMU and the Aux EICAS IDU. This data is the colored TCAS II symbols on the NDs and the RA avoidance cues on the PFDs.
Directional Antenna Inputs/Outputs The top and bottom directional antennas transmit ATC interrogation rf and receive transponder rf replies. The antennas contain four steerable element passive arrays that are mounted at 0 degrees, 90 degrees, 180 degrees, and 270 degrees relative to the airplane centerline. These antennas are unpowered, passive devices.
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NAVIGATION TCAS
TCAS II - COMPUTER
General
Power
The microprocessor-based TCAS computer is the master control unit for TCAS II. It has a computerized control system and an L-band receiver/transmitter. Operation of TCAS is controlled by TCAS II software resident in the TCAS processor memory.
The TCAS II computer operates on 115vac.
Characteristics
Control Control is from the dual mode S control panel through an ARINC 429 data bus. Both operation and functional test are selected here. A pushbutton on the front panel allows for manual self-test of TCAS.
The TCAS II computer controls all surveillance, data acquisition, tracking, advisory, and air-to-air maneuver coordination functions. Some computer capabilities are: - Surveillance of up to 45 targets/intruders, out to 30 nm - Displays up to 30 closest intruders - Communicate with up to 150 mode S transponder-equipped airplanes.
TCAS II Computer Physical Description The TCAS II computer is a 6 MCU size unit that weighs 28 lb.
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NAVIGATION TCAS
Boeing 747-400 Avionics
TCAS II - ATC/TCAS CONTROL PANEL
The ATC/TCAS control panel controls both ATC mode S transponders and the TCAS II computer. The ATC functions were covered in the ATC lesson. The TCAS functions are: - STBY Transponder does not transmit or reply to interrogation, All TCAS broadcast, surveillance and tracking operation are disabled - TA mode select is a Traffic Advisory only mode. In this mode all intruder traffic except RAs are displayed. - TA/RA mode select is a Traffic Advisory/Resolution Advisory mode. In this mode both traffic and resolution advisories are displayed. ABOVE-N-BELOW switch: - ABV display intruder airplane from 9900 feet above to 2700 feet below own airplane. - N, display intruder airplane from 2700 feet above to 2700 feet below own airplane. - BELOW, display intruder airplane from 2700 feet above to 9900 feet below own airplane. In any other mode, TCAS is placed in standby.
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NAVIGATION TCAS
TCAS II - EFIS CONTROL PANEL
General
TFC (Traffic) Pushbutton
The left and right EFIS control panels control TCAS displays on the NDs.
The EFIS control panel TFC (traffic) pushbutton controls TCAS displays on the NDs. When a TCAS display mode is selected, the TFC button is used to turn on and off TCAS symbols. When not in a TCAS display mode, the TFC button is inactive. When selected off, no symbols show, but the word TRAFFIC shows in yellow for a TA, and in red for an RA.
TCAS II EFIS ND Mode Capabilities TCAS intruder symbols show in these modes: - Expanded and center MAP modes - Expanded approach mode - Expanded VOR mode
TCAS II EFIS ND Range Selection The EFIS control panel range switch controls TCAS display capability. TCAS symbols show in all EFIS ranges, but show up better in ranges of 40nm or less.
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NAVIGATION TCAS
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TCAS II - DIRECTIONAL ANTENNA
General The TCAS II uses an upper and a lower directional antenna.
Directional Antennas The directional antennas transmit interrogations on 1030 MHz at varying power levels in each of four 90 degree azimuth segment arrays. The TCAS computer receives intruder transponder replies on 1090 MHz. Each antenna is mounted using four screws. The radiating side of the antenna has black markings of forward (FWD) and “DO NOT PAINT”.
Physical Characteristics The antenna weight is: - 1.5 lbs. The dimensions of the antenna are: - Base width 6.25 inches - Base length 11 inches - Height 1.25 inches 34.45.0711 -001
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Boeing 747-400 Avionics
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NAVIGATION TCAS
Boeing 747-400 Avionics
TCAS II - BASIC OPERATION
General The TCAS II is similar to an ATC ground station, but operates independently. The TCAS computer is an airborne interrogator that detects the presence of all mode S or ATCRBS transponder equipped airplanes. TCAS II tracks and continuously evaluates the threat potential of all intruders. TCAS II cannot detect airplanes that do not have a working ATC transponder.
Far away targets are interrogated with 24 power levels, up to the highest power (shout). TCAS II listens for mode S squitter pulse transmissions from mode S transponder equipped airplanes. This squitter pulse is transmitted once per second. When an ATCRBS or mode S transponder is detected, it is placed in the track mode. TCAS II can track up to 45 intruders at once.
Detection Capability TCAS II actively searches for ATCRBS equipped intruders with an ATCRBS-only all-call interrogation. When TCAS II interrogates ATCRBS intruders, it uses an interrogation technique called whisper shout. TCAS uses this technique when it is operated in areas where multiple intruders replies could mask or interfere with each other. The whisper shout technique varies the strength of the interrogation pulses (P1, P3 & P4) and a suppression pulse (S1) in relation to the intruders range. Close in targets are interrogated with low power (whisper).
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Boeing 747-400 Avionics
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NAVIGATION TCAS
TCAS II - COMPUTER TRACKING SCENARIO
General This scenario shows three airplanes which are possible collision threats to the TCAS equipped airplane in the center.
developed if the ATCRBS transponder does not have mode C altitude reporting capability.
Mode S Equipped Airplanes
Other TCAS Equipped Airplanes
Airplane 1 is not TCAS equipped, but has a mode S transponder. Airplane 2 is a TCAS equipped airplane. Airplane 1 transmits a mode S squitter signal once-per-second on 1090 MHz. The TCAS system monitors that frequency, and when a valid identification squitter signal is received, the airplane’s ID code is added to a list of airplanes that TCAS interrogates. This interrogation list is called a roll-call. In this scenerio, airplane 2 adds airplane 1 to its roll-call, and then interrogates and tracks airplane 1 discretely. Both TAs and RAs are available in this situation.
Airplane 4 is a TCAS equipped airplane. In this situation both TCAS airplanes produce a coordinated communication link between the mode S transponders and the TCAS computers. Both TAs and RAs are produced and a coordinated evasive action results. This is the ideal situation for collision avoidance.
ATCRBS Equipped Airplanes Airplane 3 is equipped with an ATCRBS only transponder. Airplane 2 transmits an ATCRBS-only all-call once per second. Airplane 3 replies to this interrogation with a mode C reply, and airplane 2 can now track this airplane with updated ATCRBS only interrogations. Both TAs and RAs are available in this situation. No RAs are 34.45.0713 -001
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NAVIGATION TCAS
TCAS II - PRINCIPLES
TCAS Tau Areas
TCAS Sensitivity Levels
The TCAS computer forms a protective area around the airplane as shown in the TCAS protected areas. The dimensions of this protected area vary depending on the airspeed and altitude of the TCAS airplane, and the closure rates (range and altitude) of each intruder. This protected area represents the time until the intruder will be at the closest point of approach to own airplane. This time to endanger period is called tau. TAU is the minimum time the flight crew needs to learn of a collision threat and to take evasive action. The protected area is the tau area. A traffic advisory tau defines an area around the TCAS airplane. If this area is penetrated by an intruder, and the intruder meets the relative altitude restrictions, the TCAS issues a traffic advisory alert. A resolution advisory tau is established for an RA warning in a similar manner.
The TCAS computer has variable sensitivity levels (levels 2-7) as shown in the TCAS parameters chart. The sensitivity level is selected by the TCAS computer based on own airplane altitude. Level 2 is used from zero to 500 feet, and level 7 is used above 20,000 feet. Level 2 is the least sensitive and level 7 is the most sensitive. At level 2, no RA’s can occur.
TCAS Collision Calculations The TCAS computer predicts the relative altitude of the intruder at the closest point of approach. Based on own airplane radio or barometric altitude, there is a variable altitude restriction for advisory calculation as seen in the profile chart for TCAS parameters.
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NAVIGATION TCAS
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TCAS Sensitivity Levels (cont.) The tau time in seconds varies with own airplane altitude from as little as 20 seconds to as much as 45 seconds. The vertical separation result of a resolution advisory also varies with own airplane altitude.
TCAS “DMOD” A modification of a TCAS protected area called “DMOD” provides added TCAS protection against intruders with slow closure rates. DMOD keeps these intruders from getting too close. TA and RA ranges for various intruder closure rates are shown in the TCAS range vs closure rate chart.
TCAS Antenna Radiation Patterns The TCAS computer transmits a variety of RF radiation patterns from both the top and bottom TCAS antennas. When TCAS is in communication with a mode S ATC transponder, the RF beam is transmitted in the direction of the intruder. This can be in any of the four transmit quadrants about the airplane. When TCAS transmits an ATCRBS only all-call, the RF beam pattern is radiated on both the top and bottom antenna. The TCAS favors the top antenna and the forward RF transmit quadrant for this type of transmission. 34.45.0714B-001
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NAVIGATION TCAS
TCAS II - CONTROL AND DISPLAY MESSAGES
ATC/TCAS Control Panel
EFIS Control Panel
TCAS II is controlled by the ATC/TCAS function select switch.
The EFIS mode control switch must be in either MAP, EXP APP, EXP VOR to show TCAS symbols.
If the ATC/TCAS switch is not in TA or TA/RA, the message TCAS OFF shows in yellow on the ND. This message shows in EFIS modes of MAP, EXP APP, or EXP VOR. If TCAS fails, a TCAS FAIL message shows on the ND in yellow. When TA is selected, TCAS is enabled for traffic advisories only, and the message TA ONLY shows in cyan on the ND.
The EFIS range selection should be in the 40 nm range or less to show TCAS symbols. The TFC pushbutton on the range select knob turns TCAS symbols on or off. When selected, the TFC message shows on the ND in cyan.
When TA/RA is selected, TCAS is enabled for both traffic advisories and resolution advisories. No message is displayed in this mode.
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NAVIGATION TCAS
TCAS II - NAVIGATION DISPLAYS
General
TCAS II Advisories
TCAS II intruder display symbology is determined by several IDS software control laws and program pins. Target data is sent to the IDUs on two high speed ARINC 429 buses. Range, altitude, and bearing for up to 31 intruders are sent in each data file. For TCAS to show, the TFC button must be selected, the EFIS display range must be less than 40 nm, and the ND EFIS mode must be in either MAP, EXP APP, or EXP VOR. A TCAS range ring is available in ranges below 160nm. The range ring is oriented to magnetic heading and is 3nm in diameter.
TCAS classifies intruders into four categories. Four types of symbols, with different shapes and colors, show traffic symbols. The different types of TCAS II intruders are:
Intruder An intruder is any airplane being processed by the TCAS II computer threat detection logic as a potential threat. Traffic advisories (TAs) are issued for intruders with active tranpsonders. TCAS II shows TAs for all intruders evaluated as threats on the EFIS NDs.
- Other traffic - Proximate traffic - Traffic advisory (TA) - Resolution advisory (RA) These symbols show the relative position (range and usually bearing) of all intruders that are, or could become collision threats. In addition, a TA also shows intruder relative altitude up to +/- 2700 feet, and if the intruder is ascending or descending.
Non-Threat Displays Non-threat or other traffic shows as a white open diamond. These represent airplanes with a range greater than 6 nm or relative altitude greater than 1200 feet.
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NAVIGATION TCAS
Proximate Traffic Proximate traffic shows as a solid, white-filled diamond. These are airplanes within 6 nm range and +/- 1200 feet relative altitude. Proximate traffic is not considered a threat, but only shows to assist the flight crew in visually acquiring the intruder.
are: - 20 sec. at 500-2500 feet - 25 sec. at 2500-10,000 feet - 30 sec. at 10,000-20,000 feet - 35 sec. at 20,000 feet & ABOVE
Traffic Advisory (TA) Traffic TAs show as a solid, yellow-filled circle. These are intruders within a specified number of seconds to closest point of approach (CPA). This gives the flight crew time to visually acquire the intruder. No vertical collision avoidance maneuvers are commanded for a TA. The altitude and seconds to CPA are:
For takeoff or landing, RAs are inhibited under 500 feet, and aural announcements are inhibited under 400 feet.
- 35 sec. between 500-2500 feet - 40 sec. between 2500-10,000 feet - 45 sec. above 10,000 feet
Resolution Advisory (RA) Traffic RAs show as a solid, red square. RAs are issued only when the intruder has altitude reporting capability. This vertical resolution advisory warns the flight crew when a collision course is determined and provides vertical flight cues to avoid a collision. These intruders require a vertical flight maneuver to avoid a collision. The altitude and seconds to CPA to make the maneuver 34.45.0716B-003
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NAVIGATION TCAS
Altitude Readout
Traffic Message
Intruder relative altitude shows as two digits that represents altitude in hundreds of feet. The color is the same as the traffic symbol. The size of the digits are small for other and proximate traffic, and medium double-stroke for TAs and RAs. If the intruders relative altitude is above you, the digits apear above the symbol with a plus sign. If the intruder is below you, the digits apear below the symbol with a minus sign. If the relative altitude is NCD, the altitude readout is not displayed.
A yellow TA or red RA TRAFFIC message shows at the right center in the expanded EFIS modes and on the upper right side of the ND for all full rose EFIS modes.
Vertical Motion Arrow
Off-Scale Traffic Off-scale traffic (TA or RA traffic only) shows as a yellow (TA) or a red (RA) OFF-SCALE message. The message shows on the right center of the ND in the expanded EFIS modes and on the upper right side of the ND for all full rose EFIS modes, when the intruder is out of EFIS display range.
An arrow pointing up or down, the same color as the traffic symbol, is placed on the right side of the symbol to show the intruder is either climbing or descending at a rate greater than 500 feet-per-minute.
No-Bearing Traffic A no-bearing (bearing NCD) TA or RA symbol shows on the upper right side of the ND. Each no-bearing intruder shows on a single line with TA or RA on the left, followed by the range in miles and tenths of a mile, followed by relative altitude, and by a vertical motion arrow. This data is yellow for TAs and red for RAs. There is a maximum of two no-bearing symbols shown at a time. Priority is the closest RAs and then TA intruders. 34.45.0716C-003
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NAVIGATION TCAS
Boeing 747-400 Avionics
TCAS II - PRIMARY FLIGHT DISPLAY
General The primary flight display (PFD) shows the flight crew vertical avoidance maneuver cues in response to a TCAS resolution advisory (RA). The PFD shows a red pitch maneuver symbol on the attitude display and a red vertical speed band on the vertical speed indicator.
TCAS On Attitude Display An up or down vertical pitch advisory is generated for one or multiple RAs. The position of this TCAS symbol is a function of the TCAS resolution advisory computed data. Provisions are made to ensure this TCAS symbol is always in view relative to the display range of the PFD attitude background raster area.
TCAS On Vertical Speed Indicator Display TCAS vertical speed data on the PFD shows as either an up or down red bar. The red bar(s) indicate recommended values of vertical speed to be avoided (preventative advisory, up or down). The red bar(s) always extend from one extreme of the scale to some value within the range of the scale. 34.45.0717 -004
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NAVIGATION TCAS
Boeing 747-400 Avionics
34.45.0217 -004
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NAVIGATION TCAS
Boeing 747-400 Avionics
NOTES:
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NAVIGATION TCAS
Boeing 747-400 Avionics
TCAS II - AURAL MESSAGES
General Traffic advisories (TAs), resolution advisories (RAs) and TCAS self-test are announced with computer-generated aural voice messages.
Traffic Advisory Aural For each traffic advisory, the aural “TRAFFIC, TRAFFIC” is announced. This announcement directs the flight crew to monitor the ND to help visually acquire the intruder. The TA may be a new intruder, proximity, or other traffic which has been upgraded. A TA normally precedes an RA by 15 or more seconds.
- “MONITOR VERTICAL SPEED - MONITOR VERTICAL SPEED”: This message tells the flight crew to maintain the current vertical speed rate. The airplane symbol cannot cross the RA pitch command cue. If an earlier corrective resolution advisory is changed to a preventive advisory, the aural is only announced once. Corrective type advisory aurals are either initial action or increased action types. Examples of initial action corrective RA aurals when the airplane symbol is inside the RA pitch cue are: - “CLIMB, CLIMB, CLIMB (or DESCEND)” requires a maneuver at the rate indicated by the pitch cue on the PFD, nominal 1500 feet-per-minute.
Resolution Advisory Aurals Resolution advisory aurals are announced with all RAs. These announcements are either preventive or corrective types. Preventive RA aural advisories are announced when the airplane symbol is not inside the resolution advisory pitch cue. An example of a preventive aural is:
34.45.0718A-001
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NAVIGATION TCAS
Boeing 747-400 Avionics
Resolution Advisory Aurals (cont) - “CLIMB, CROSSING CLIMB - CLIMB, CROSSING CLIMB (or DESCEND)” requires a maneuver at the rate indicated by the pitch cue on the PFD and shows the airplane flight path will cross the intruder’s flight path. - “REDUCE CLIMB - REDUCE CLIMB (or DESCEND)” tells the flight crew to reduce the rate of vertical speed to that shown on the PFD.
TCAS self-test aurals are announced upon completion of the TCAS self-test, examples are: - “TCAS TEST OK” announced for a pass of the TCAS system test - “TCAS TEST FAIL” announced when the TCAS system fails the test
Increased action corrective RA aurals change from initial action to an increased action command and require immediate crew action. Examples of increased action corrective RA aurals are: - “CLIMB, CLIMB NOW - CLIMB, CLIMB NOW (or DESCEND)” follows a descend or climb advisory, after it has been determined that a quick reversal of a current vertical pitch maneuver is necessary to provide adequate airplane separation. - “INCREASE CLIMB - INCREASE CLIMB (or DESCENT)” alerts the flight crew to increase the vertical pitch maneuver to a nominal 2500 feet-per-minute rate. An end-of-threat aural announcement is made when the intruder range starts to increase and there is no longer danger of a collision: - “CLEAR OF CONFLICT” tells the flight crew that the TCAS intruder encounter has ended. The flight crew should return to the previous flight level clearance. 34.45.0718B-001
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NAVIGATION TCAS
Boeing 747-400 Avionics
34.45.0218 -001
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NAVIGATION TCAS
Boeing 747-400 Avionics
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NAVIGATION TCAS
Boeing 747-400 Avionics
34.45.0219 -002
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NAVIGATION TCAS
Boeing 747-400 Avionics
NOTES:
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NAVIGATION TCAS
Boeing 747-400 Avionics
TCAS II - SYSTEM INPUTS/OUTPUTS
General The TCAS computer gets a variety of sensor and airplane system inputs. The CPU uses these inputs to produce the traffic and resolution advisories. The input/output (I/O) section has an interface with the TCAS central processor. ARINC 429 data and digital discretes come into the TCAS computer.
the Flight Leg in the non-volatile memory of the TCAS processor. - The left, center and right EIU sends RA status discretes to tell the TCAS if the IDS system can show an RA. - Four program pins set the selection of the airplane altitude performance capability, self-test and audio level parameters.
I/O Discretes and Program Pins The I/O section gets airplane system and sensor discretes along with TCAS system program pin settings. The CPU gets this data from internal ARINC data buses. These I/O signals are: - IRU data which comes from the IRU selected by the First Officer. Magnetic heading is the only IRU input used at this time. The other IRU inputs are reserved for future TCAS development. - The GPWC sends three discretes that inhibit RAs during windshear, ground prox warnings or alerts. - The landing gear control module sends an up/down discrete that tells the TCAS processor the position of the landing gear control lever. This sets the bottom TCAS antenna in the omni-directional mode when the landing gear is down. - The air/ground relay sends an air/ground discrete that prevents TCAS test in air. If the CMC fails, the air/ground relay increments 34.45.0720A-001
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NAVIGATION TCAS
Input/Output Section Voice Output The input/output section of the TCAS computer interfaces a variety of airplane systems with the TCAS CPU. Input/output systems include:
The MAEWA aural synthesizer cards get TCAS voice announcements from the speech prom for TA and RA advisories and for test audio.
- The selected air traffic control (ATC) transponder sends the control panel TCAS mode, own airplane Mode S ID address, and the barometric altitude to the TCAS CPU. The TCAS processor sends real-time and periodic data to the selected transponder. This is the type of equipment and TCAS coordination update data from other intruder TCAS equipped airplanes. - The left and right radio altimeters (RAs) sends radio altitude data to the TCAS computer. Only one RA is needed for TCAS operation. - The central maintenance computer (CMC) communicates with TCAS for ground test and fault monitor. - An ARINC data buffer is used as an interface between the CPU and the I/O sections.
Mutual Suppression Generator A suppression pulse is generated each time the TCAS computer transmits an interrogation and suppresses the active ATC and both DME’s. The TCAS computer receiver is suppressed when the active ATC or either of the DME’s transmit. 34.45.0720B-001
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NAVIGATION TCAS
Boeing 747-400 Avionics
34.45.0220 -001
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Boeing 747-400 Avionics
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NAVIGATION TCAS
TCAS II - MICROPROCESSOR OPERATION
General The microprocessor based TCAS processor is the master control unit in the TCAS II system. It has a combined computerized control system and an L-band receiver/transmitter. Operation of the TCAS system is controlled by TCAS software in the CPU (central processor unit) and memory section. The TCAS CPU routinely reads and stores own airplane input data.
Microprocessor Functions The TCAS processor coordinates the data from the I/O sections and uses it along with received signals from other airplane transponders to compute traffic solutions and set transmission levels. The CPU is really three separate microprocessors that work together to process all traffic. The processor interfaces with global data and address buses through an ARINC transceiver and a buffer.
signals necessary to receive and transmit mode S and mode C interrogations through the RF assembly. The signal processor operates under command of system software.
Receiver/Transmitter Functions The R/T section links the TCAS II computer to other airplanes that may represent a collision threat. The R/T has four separate receivers that receive rf from other transponders on 1090 MHz from both the top and bottom TCAS directional antennas. This rf goes to the I/F video processor where it is converted to digital signals for computation in the signal processor. The signal processor sends signals to the modulator where it is formatted for use by the transmitter to interrogate ATC transponders on 1030 MHz.
Signal Processor Functions The primary purpose of the signal processor section is as a pre-processor of data that is transferred between the R/T section, the CPU, and I/O cards. The signal processor generates all timing 34.45.0721A-001
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NAVIGATION TCAS
Boeing 747-400 Avionics
Top and Bottom TCAS Antennas These directional antennas are electronically steerable phased arrays with four beam forming elements. These antennas both transmit and receive rf for communication with any ATC transponders within range of the TCAS airplane. During TCAS transmission, the top or bottom directional antenna radiates the 1030 MHz on a main beam pattern or an omni beam pattern. Beam pattern is under control of the four antenna element drive signals from the TCAS processor. The landing gear discrete causes the bottom antenna to radiate in an omni-directional pattern when the gear is down. TCAS mode S and ATCRBS interrogations are normally transmitted using the directional main beam, while the ATCRBS suppression pulse (P2) is transmitted in an omni pattern. During TCAS receptions, each of the four directional antenna elements receives any 1090 MHz signals from other airplane transponders. The phasing of these signals is determined by the direction the rf energy is received. This direction data goes to the TCAS receiver section for analysis in the TCAS signal processor.
34.45.0721B-001
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NAVIGATION TCAS
Boeing 747-400 Avionics
34.45.0221 -001
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NAVIGATION TCAS
Boeing 747-400 Avionics
MANUAL SELF TEST Receiver/Transmitter Self-Test The TEST switch on the TCAS computer starts a self-test that operates as follows: - All LED indicators are normally off. - Push and hold for 2 seconds, the TEST button on the front panel of the TCAS computer. - All of the LED indicators come on for 3 seconds. - The TCAS PASS LED indicator stays on if there is no failure to the TCAS computer or other essential systems that interface with TCAS. - The applicable LED failure indicator comes on if there is a failure LEDs
FAILURE
TCAS PASS TCAS FAIL TOP ANT BOT ANT HDG RA LOG TA DISPLAY RA DISPLAY RAD ALT XPDR BUS ATT
TCAS OK (NO FAILURE) TCAS COMPUTER TOP TCAS ANTENNE OR CIRCUIT BOTTOM TCAS ANTENNE OR CIRCUIT INVALID HEADING DATA NOT USED NOT USED PFD FAILURE RADIO ALTIMETER INPUT MODE S TRANSPONDER INPUT INVALID ATTITUDE DATA
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NAVIGATION TCAS
Boeing 747-400 Avionics
34.45.222.010
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NAVIGATION TCAS
Boeing 747-400 Avionics
TCAS II - CMC GROUND TEST
General A TCAS CMC ground test is available from any CDU in the flight deck.
Ground Test Operation To start a TCAS CMC ground test, first access the CMC Chapter 34 Navigation Radios Ground Test pages on the CDU. Push the LSK next to TCAS. Push the start test LSK next to TCAS and the TCAS pre-condition screen appears. If these pre-conditions are met, push the start test LSK to complete the test. If the system passes the test the word PASS shows on the right side of the screen. If the system fails the test the word FAIL shows. Push the LSK next to the fail message to show the CMC ground test message page where the CMC lists the fail message.
34.45.0723 -002
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NAVIGATION TCAS
Boeing 747-400 Avionics
34.45.0223 -002
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NAVIGATION TCAS
Boeing 747-400 Avionics
TCAS II - FLIGHT DECK EFFECTS AND CMC MESSAGES
Flight Deck Effects A TCAS II failure causes the message TCAS FAIL to show on both ND’s. Advisory EICAS messages include: - >TCAS SYSTEM means data is not displayable on IDS - >TCAS RA CAPT means resolution advisories cannot be displayed on the Captain’s PFD - >TCAS RA F/O means resolution advisories cannot be displayed on the F/O’s PFD - >TCAS OFF means the TCAS system is off The status message TCAS SYSTEM appears for a fault in the TCAS display signal.
CMC Messages Fifteen CMC messages show for faults that are reported to the CMC by TCAS. These messages assist in troubleshooting TCAS.
34.45.0724 -002
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NAVIGATION TCAS
Boeing 747-400 Avionics
34.45.0224 -002
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Boeing 747-400 Avionics
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NAVIGATION Radio Altimeter System
Boeing 747-400 Avionics
RADIO ALTIMETER (RA) SYSTEM ................................................ 2 RADIO ALTIMETER SYSTEM COMPONENT LOCATIONS - 1 ..... 4
RADIO ALTIMETER SYSTEM - EFIS CONTROL PANEL DH-MDA SET CONTROL ....................................................................... 22
RADIO ALTIMETER SYSTEM COMPONENT LOCATIONS - 2 ..... 6 RADIO ALTIMETER SYSTEM POWER AND ANTENNA INTER-
RADIO ALTIMETER SYSTEM - CONTROL DISPLAY UNIT - EFIS CONTROL ............................................................................... 24
FACES ..................................................................................... 8 RADIO ALTIMETER SYSTEM - DISCRETE INPUTS..................... 10
RADIO ALTIMETER SYSTEM - PRIMARY FLIGHT DISPLAY ........ 27 RADIO ALTIMETER SYSTEM - EICAS DISPLAYS ........................ 30
RADIO ALTIMETER SYSTEM - CMC INPUT ................................. 12 RADIO ALTIMETER SYSTEM - DATA BUS OUTPUTS ................. 14
LEFT RADIO ALTIMETER SYSTEM - SEARCH MODE ................ 32 LEFT RADIO ALTIMETER - TRACK MODE .................................. 34
RADIO ALTIMETER RECEIVER/TRANSMITTER .......................... 16 RADIO ALTIMETER ANTENNA ...................................................... 18
LEFT RADIO ALTIMETER SYSTEM MONITORING/TESTING ...... 36 RADIO ALTIMETER SYSTEM SELF-TEST ................................... 38
RADIO ALTIMETER SYSTEM PRIORITY SELECTION ................. 20
RADIO ALTIMETER SYSTEM GROUND TESTS .......................... 40
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NAVIGATION Radio Altimeter System
Boeing 747-400 Avionics
RADIO ALTIMETER (RA) SYSTEM
The radio altimeter (RA) system provides accurate measurement of absolute altitude (height above the terrain) from 2500 feet to touchdown. The system is used primarily during the approach, landing and takeoff phases of flight.
Fault summary data is sent to the central maintenance computers (CMCs) via the EIUs. The primary flight display (PFD) provides a visual display of radio altitude.
Three radio altimeter systems are installed. They consist of: The EICAS display provides a visual display of RA system status. - One Radio Altimeter Receiver/ Transmitter (RA R/T) - One RA transmit antenna
Fault memory within the RA R/T uses the air/ground discrete to establish flight segments.
- One RA receive antenna
The CMC outputs a digital test discrete to initiate a ground test.
Radio altitude data is sent on digital data buses to these LRUs:
34.33.0501 -001
- Flight control computer (FCC) - Modularized avionics and warning electronics assembly (MAWEA) (left and right RA R/Ts only) - Ground proximity warning computer (GPWC) (left and richt RA R/ T only) - EFIS/EICAS interface units (EIUs)
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NAVIGATION Radio Altimeter System
Boeing 747-400 Avionics
34.33.0001 -001
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NAVIGATION Radio Altimeter System
Boeing 747-400 Avionics
RADIO ALTIMETER SYSTEM COMPONENT LOCATIONS - 1
The radio altimeter system components in the center equipment center are the: - Left RA receiver/transmitter - Center RA receiver/transmitter - Right RA receiver/transmitter The RA system components on the bottom of the fuselage are the: - Left RA receive antenna - Center RA receive antenna - Right RA receive antenna - Left RA transmit antenna - Center RA transmit antenna - Right RA transmit antenna 34.33.0502 -001
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NAVIGATION Radio Altimeter System
Boeing 747-400 Avionics
34.33.0002 -001
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NAVIGATION Radio Altimeter System
Boeing 747-400 Avionics
RADIO ALTIMETER SYSTEM COMPONENT LOCATIONS - 2
The radio altimeter system components and interfacing components located in the flight deck are the: - Primary flight displays - Left and right EFIS control panels - Left and right control display units - Left radio altimeter circuit breaker - Right radio altimeter circuit breaker - Center radio altimeter circuit breaker 34.33.0503 -001
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NAVIGATION Radio Altimeter System
Boeing 747-400 Avionics
34.33.0003 -001
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NAVIGATION Radio Altimeter System
Boeing 747-400 Avionics
RADIO ALTIMETER SYSTEM POWER AND ANTENNA INTERFACES
Power The radio altimeter receiver/transmitters are powered by: - 115v ac bus 3 (left RA R/T) - 115v ac bus 2 (right RA R/T) - 115v ac bus 1 (center RA R/T)
Antenna Interfaces The transmit antennas send RF signals toward the terrain. The receive antennas couple reflected RF signals into the receiver circuits of the RA R/Ts. 34.33.0504 -001
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NAVIGATION Radio Altimeter System
Boeing 747-400 Avionics
34.33.0004 -001
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NAVIGATION Radio Altimeter System
Boeing 747-400 Avionics
RADIO ALTIMETER SYSTEM - DISCRETE INPUTS 34.33.0505 -002
Test Inhibit The test inhibit input from the FCC to the RA R/T supplies a functional test inhibit signal. This prevents the RA R/T from being manually tested during an automatic landing.
Air/Ground Discrete All faults detected within the RA R/T are stored in a nonvolatile fault memory. The faults are stored by flight segments. Each flight segment is initiated when the airplane becomes airborne as detected by the air/ground relay.
Input Program Pins The continuous data program pins are jumpered to assure a continuous data output to the FCC, regardless of the validity of the sign/status matrix (SSM). The aircraft installation delay (AID) program pins are jumpered for an AID 57 feet. This calibrates the system so that the altitude readout is zero at touchdown. It compensates for the length of the antenna cables plus fuselage to ground distance.
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NAVIGATION Radio Altimeter System
Boeing 747-400 Avionics
34.33.0005 -001
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NAVIGATION Radio Altimeter System
Boeing 747-400 Avionics
RADIO ALTIMETER SYSTEM - CMC INPUT
Any of the three CDUs may be used to request fault information and initiate a test of the radio altimeter systems via the CMCs. Normally, the left CMC outputs a digital test discrete to initiate a test. If the left CMC fails, a relay in the left CMC energizes routing right CMC data to the RA R/Ts. 34.33.0506 -001
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NAVIGATION Radio Altimeter System
Boeing 747-400 Avionics
34.33.0006 -001
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NAVIGATION Radio Altimeter System
Boeing 747-400 Avionics
RADIO ALTIMETER SYSTEM - DATA BUS OUTPUTS
General The radio altimeter systems provide data to the:
Altitude data from the left RA system is sent to the GPWC for ground proximity alert and warning logic.
- Left, center, and right EFIS/EICAS interface units (EIUs) - Left, center, and right FCCs
Altitude data from the left and right RA systems is sent to the master monitor cards in the MAWEA for warning logic.
- Ground proximity warning computer (GPWC) Fault Summary Data - Modularized avionics and warning electronics assembly (MAWEA)
Altitude Data Computed radio altitude from three RA systems is routed to each of the three EIUs. The EIUs multiplex this information with inputs from other airplane systems, and provide an output to the captain's and first officer's PFD. Each EIU provides an output to each PFD. Altitude data from the left, right and center RA systems is sent to the FCCs for approach logic.
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Fault summary words from each radio altimeter system are also sent to each EIU. The EIUs send the data to: - The central maintenance computers (CMCs) - The auxiliary EICAS display The CMCs store the fault summary word in nonvolatile memory. Upon request from any control display unit (CDU) the left CMC will send the fault summary data to the CDU for display. 34.33.0507 -001
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NAVIGATION Radio Altimeter System
Boeing 747-400 Avionics
34.33.0007 -001
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NAVIGATION Radio Altimeter System
Boeing 747-400 Avionics
RADIO ALTIMETER RECEIVER/TRANSMITTER
Purpose The radio altimeter (RA) receiver/transmitter:
- Forced air cooling is required
- Transmits frequency-modulated continuous-wave signals Operation - Receives the reflected signals Four LED status indicators are provided on the front panel: - Computes the altitude - Sends the computed data to the aircraft systems requiring radio altitude.
- A green LED labeled SYSTEM OK indicates valid receiver/ transmitter operation - A red LED labeled R/T UNIT indicates a receiver/transmitter fault
Characteristics
- A red LED labeled ANT indicates an antenna fault
These are the specifications of the RA R/T:
- A red LED labeled IND. This is inoperative
- Frequency = 4,300 MHz +/- 123 MHz
A TEST pushbutton is provided to initiate a self-test.
- Transmit power = 70 mw nominal
The RA R/T has a non-volatile memory for storing fault information from the last sixty-three flights. It can store up to thirteen faults per flight.
- Operating range = -20 to 2500 feet - Warm up time = 1 minute
Fault memory data can be read out through the Automatic Test Equipment (ATE) connector on the front of the unit. 34.33.0508 -002
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NAVIGATION Radio Altimeter System
Boeing 747-400 Avionics
34.33.0008 -002
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NAVIGATION Radio Altimeter System
Boeing 747-400 Avionics
RADIO ALTIMETER ANTENNA
Purpose The RA receive antenna senses RF in the 4200 MHz to 4400 MHz range. The antenna couples the RF signal to the receiver circuits for detection. The RA transmit antenna couples RF from the transmitter toward the terrain below the aircraft.
The radiation side of the antenna carries the red markings FWD and DO NOT PAINT. Paint should never be applied to the radiating surface or to the backplate of the antenna casing. 34.33.0509 -001
Characteristics - Frequency = 4200 MHz to 4400 MHz - Impedance = 50 Ohms - Finish is gloss white polyurethane enamel
Antenna Removal/Installation Each of the three RA R/T units is connected to a dedicated transmit antenna and a dedicated receive antenna. The transmit and receive antennas are identical and interchangeable. Each antenna is mounted by means of four screws. An O-ring seated in a groove around the connector mounting assures environmental protection.
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NAVIGATION Radio Altimeter System
Boeing 747-400 Avionics
34.33.0009 -001
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NAVIGATION Radio Altimeter System
Boeing 747-400 Avionics
RADIO ALTIMETER SYSTEM PRIORITY SELECTION
Purpose The EIU source select switches allow the flight crew to select either the left, center or right EIU input to their respective PFDs. The PFDs determine which radio altimeter system data will be displayed.
Operation Each EIU receives radio altitude data from all three RA systems. The PFD determines which radio altitude data will be used for display. The PFD considers these conditions in determining which radio altitude data to use:
Each EIU input to the PFD contains altitude information from the left, center, and right RAs. Priority programming determines which of the three radio altitude data signals (all within each EIU input into the PFD) will be displayed. RA system status is monitored by the PFD. If the displayed RA system fails, data from the next highest priority RA system will be shown. Priority for each EIU source selection is shown.
- EIU source select switch position - Priority programming
34.33.0510 -001
- RA system statusThe EIU source select switch position determines which EIU input to process.
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NAVIGATION Radio Altimeter System
Boeing 747-400 Avionics
34.33.0010 -001
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NAVIGATION Radio Altimeter System
Boeing 747-400 Avionics
RADIO ALTIMETER SYSTEM - EFIS CONTROL PANEL DH-MDA SET CONTROL
Purpose The EFIS control panel provides controls for selecting decision height (DH) and for resetting an active DH alert. Selections are displayed on the captain's and first officer's PFDs. The left EFIS control panel controls the captain's PFD, the right EFIS control panel controls the first officer's PFD.
With DH selected, the 24-detent position 360 degree rotary switch adjusts the DH from zero feet to +999 feet. The RST (reset) switch allows manual reset of the DH alert. The MDA function is not related to radio altimeter system operation.
Operation 34.33.0511 -001
The DH-MDA set control consists of: - A two-position rotary switch - A 24-detent position 360 degree rotary switch - An RST pushbutton switch. The two-position rotary switch provides: - Decision height selection - Minimum descent altitude (MDA) selection
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NAVIGATION Radio Altimeter System
Boeing 747-400 Avionics
34.33.0011 -001
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NAVIGATION Radio Altimeter System
Boeing 747-400 Avionics
RADIO ALTIMETER SYSTEM - CONTROL DISPLAY UNIT - EFIS CONTROL
Purpose In the event that an EFIS control panel should fail, the EFIS control page on the CDU is used to enter decision height information. It is also used to reset decision height alerts. The EFIS control page is accessed from the CDU main menu page.
Operation After an EFIS control panel failure, the EFIS control page will display the last decision height value received from the EFIS control panel. The DH may be changed by keyboard entry on the CDU. Valid entries are -20 to 999 feet. The line select key next to DH reset allows manual reset of a DH alert. DH reset from a CDU is possible only after the failure of the onside EFIS control panel.
34.33.0512 -001
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NAVIGATION Radio Altimeter System
Boeing 747-400 Avionics
34.33.0012 -001
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NAVIGATION Radio Altimeter System
Boeing 747-400 Avionics
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NAVIGATION Radio Altimeter System
Boeing 747-400 Avionics
RADIO ALTIMETER SYSTEM - PRIMARY FLIGHT DISPLAY
Purpose
Decision Height Alert
The PFD shows radio altitude and decision height for use primarily during approach and landing.
Decision height alert is armed when the airplane climbs through an altitude of 75 feet above the selected decision height.
Radio Altitude Display
As the airplane descends through the selected decision height value:
Radio altitude is displayed digitally for altitudes between -20 and 2500 feet. The display updates in: - 2 foot increments from -20 to 100 feet - 10 foot increments from 100 to 500 feet - 20 foot increments from 500 to 2500 feet Above 2500 feet the display is blank.
- The radio altitude readout changes from white to yellow - The green decision height display changes to large yellow letters DH - During the first three seconds the letters DH blink. The DH alert can be reset by: - Pressing the RST pushbutton switch on the EFIS control panel - Ascending to a height 75 feet above the selected decision height - Automatic reset at touchdown
Decision Height Display The decision height is displayed above the radio altitude. It includes the letters DH and the selected value. If the DH selected is less than zero feet, or greater than 999 feet, the display is blank.
When reset, the DH readout returns to the normal green display and the RA readout returns to white.
34.33.0513A-001
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Invalid Data Invalid RA data: - Is indicated by a yellow RA flag - Occurs when the RA R/T detects a failure in the RA system Invalid EFIS control panel DH data: - Is indicated by a yellow DH flag when the radio altitude is less than or equal to 2500 feet. - Is indicated by a blank display when the radio altitude is more than 2500 feet. - Occurs when the EFIS control panel detects an internal failure. When RA data and DH data are both invalid, the yellow RA and DH flags are displayed.
No Computed Data (NCD) RA NCD: - Is indicated by a blank RA display - Occurs when the transmitted signals return is too weak for normal operation 34.33.0513B-001
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Boeing 747-400 Avionics
34.33.0013 -001
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NAVIGATION Radio Altimeter System
Boeing 747-400 Avionics
RADIO ALTIMETER SYSTEM - EICAS DISPLAYS
Purpose RA system EICAS status messages inform the flight or maintenance crew of a failed RA system. These messages appear on the status page of the auxiliary EICAS display.
General Description RA system status data is continuously sent to the EIUs. When the status page is selected any RA system failure will appear on the lower left of the auxiliary EICAS display. 34.33.0514 -001
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34.33.0014 -001
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NAVIGATION Radio Altimeter System
Boeing 747-400 Avionics
LEFT RADIO ALTIMETER SYSTEM - SEARCH MODE
Transmit and Receive The RA receiver/transmitter transmits a FM/CW signal through the transmit antenna. This signal consists of a CW carrier frequency modulated sawtooth wave. The frequency deviation of the sawtooth wave is 123 mHz from 4328 mHz to 4362 mHz.
Search Mode As a signal is transmitted, reflected from the terrain, and picked up by the receive antenna its frequency remains the same. The frequency of the wave being transmitted at the moment the signal returns is different from the frequency of the return signal. Delta t is the time required for the signal to reach the terrain and return. Delta F is proportional to delta t and to the slope of the sawtooth wave. As the slope decreases with each period, delta F decreases. When delta F equals 25 kHz the altimeter switches to the track mode. 34.33.0515 -002
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34.33.0015 -002
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LEFT RADIO ALTIMETER - TRACK MODE
Track Mode When the comparator determines that delta F is 25 kHz the transceiver switches to the track mode. In the track mode, the slope of the sawtooth wave is held at the value that produces a delta F of 25 kHz. The time period of the wave being transmitted is sent to the altitude processor. This time period is used to compute altitude in the altitude processor. The altitude processor sends radio altitude to the 429 transmitter to send out on data buses 1 and 2.
Input Program Pins The continuous data program pin is jumpered to assure non-interrupted data output regardless of validity. The aircraft installation delay (AID) program pin is jumpered for 57 feet. This calibrates the system so that the altitude readout is zero at touchdown. It compensates for the length of the antenna cables plus fuselage to ground distance. 34.33.0520 -001
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34.33.0020 -001
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LEFT RADIO ALTIMETER SYSTEM MONITORING/TESTING
BITE Module The BITE module monitors the circuits in the RA receiver/transmitter for faults. These faults are grouped by flights. Faults are stored in the RA R/T and are read out in the shop through the automatic test equipment (ATE) connector. The CMCs define a flight for the R/T's internal flight fault memory.
Test
A test inhibit discrete is sent from the left FCC to the left RA R/T during an automatic landing. A discrete from the air/ground relay inhibits self-test during flight and is an alternate source of defining flight legs.
34.33.0516 -001
An RA system self-test is initiated from the TEST switch on the front of the RA R/T. The results of a self-test are seen on the LED indicators on the face of the RA R/T. A ground test can be initiated on a control display unit (CDU). When the ground test is initiated, a test command will be generated by the CMC and sent to the RA R/T to start the test. The results of a ground test are sent to the CMCs via the EIUs for display on the CDU. Status information is continuously sent from the RA R/T to the CMCs via the EIUs. This is for fault monitoring of the RA system.
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34.33.0016 -002
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RADIO ALTIMETER SYSTEM SELF-TEST
Operation To initiate a self test of the RA system press the TEST switch on the RA R/T front panel. When the TEST switch is pressed and held, the front panel LEDs will come on for three seconds to indicate that they are operative. The lights then go off for three seconds. After this period, the appropriate LEDs will come on to indicate either a normal (green) or fault (red) condition. The LEDs will remain on until the test switch is released. During test, the red R/T LED will also illuminate if failures have occurred during two or more of the last four flights. During the self-test a radio altitude of 40 +/-2 feet is shown on the PFD. This radio altitude is seen as long as the TEST switch is pressed.
Test Inhibit The self-test function is inhibited by a test inhibit discrete. This discrete is received from the flight control computer during a normal automatic landing.
34.33.0517 -001
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34.33.0017 -002
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RADIO ALTIMETER SYSTEM GROUND TESTS
Ground Test Ground tests of the radio altimeter systems are selected using the CDU. The ground test systems page on the CDU identifies the ATA chapters which have ground test capabilities. Press the line select key next to 34 NAVIGATION to show the GROUND TESTS page. To initiate a test of one of the radio altimeter systems press the line select key next to that system.
Ground Test Results The word PASS on the same line as the system tested indicates the system passed the ground test. Failure of the ground test is indicated by the word FAIL next to the system selected for ground test. Pressing the line select key next to FAIL causes the GROUND TEST MESSAGE page to be shown. This page gives more specific information about the test failure.
34.33.0518 -001
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34.33.0018 -001
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NAVIGATION Ground Proximity Warning System
Boeing 747-400 Avionics
GROUND PROXIMITY WARNING SYSTEM INTRODUCTION ...... 2 GROUND PROXIMITY WARNING SYSTEM .................................. 4
GPWS - MODE 5 OPERATION ..................................................... 67 GPWS - MODE 6 DESCRIPTION ................................................. 70
GPWS - GROUND PROXIMITY MODES ...................................... 6 GPWS - COMPONENT LOCATIONS - I ........................................ 8
GPWS - MODE 6 OPERATION ..................................................... 73 GPWS - MODE 7 DESCRIPTION ................................................. 76
GPWS - COMPONENT LOCATIONS - 2 ....................................... 10 GPWS - ARINC 429 INPUTS ......................................................... 12
GPWS - MODE 7 OPERATION ..................................................... 79 GPWS - TERRAIN AWARENESS FUNCTION .............................. 83
GPWS - ANALOG INPUTS ............................................................ 17 GPWS - ANALOG OUTPUTS ........................................................ 20
GPWS - TERRAIN CLEARANCE FLOOR..................................... 87 GPWS - ENVELOPE MODULATION DESCRIPTION .................... 90
GPWS - DIGITAL BUS OUTPUTS ................................................. 22 GPWS - GROUND PROXIMITY WARNING COMPUTER ............. 25
GPWS - ENVELOPE MODULATION OPERATION ....................... 92 GPWS - POWER AND ANALOG INPUTS ..................................... 95
GPWS - CONTROL COMPONENTS ............................................ 29 GPWS - PFD AND MASTER WARNING LIGHT ANNUNCIATIONS 32
GPWS - TERRAIN SELECT RELAY INTERFACE ......................... 98 GPWS - EFIS CONTROL PANEL.................................................. 100
GPWS - MODE 1 DESCRIPTION ................................................. 34 GPWS - MODE 1 OPERATION ..................................................... 37
GPWS - BITE FUNCTION OPERATION ........................................ 103 GPWS - FLIGHT DECK SELF-TESTS – 1 .................................... 106
GPWS - MODE 2A DESCRIPTION ............................................... 41 GPWS - MODE 2B DESCRIPTION ............................................... 44
GPWS - FLIGHT DECK SELF-TESTS – 2 .................................... 108 GPWS - LEVEL 1 - SELF TEST .................................................... 110
GPWS - MODE 2 OPERATION ..................................................... 47 GPWS - MODE 3 DESCRIPTION ................................................. 51
GPWS - LEVELS 2-5 - SELF-TEST .............................................. 114 GPWS - LEVEL 6 - SELF TEST .................................................... 118
GPWS - MODE 3 OPERATION ..................................................... 55 GPWS - MODE 4 DESCRIPTION ................................................. 58
GPWS - STATUS LEDS ................................................................. 120 GPWS - SELF-TEST - 1 ................................................................ 123
GPWS - MODE 4 OPERATION ..................................................... 61 GPWS - MODE 5 DESCRIPTION ................................................. 64
GPWS - SELF-TEST - 2 ................................................................ 126 GPWS - FLIGHT DECK EFFECTS ............................................... 128
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GROUND PROXIMITY WARNING SYSTEM INTRODUCTION The purpose of the ground proximity warning system (GPWS) is to alert the flight crew about a condition that is not safe because of near terrain. It also provides a warning when windshear conditions are present. Aural messages, lights and CRT displays annunciate GPWS warnings and alerts in the flight deck.
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NAVIGATION Ground Proximity Warning System
GROUND PROXIMITY WARNING SYSTEM System Overview
Status
The main component of the GPWS is the ground proximity warning computer (GPWC). It uses inputs from the various systems to determine the presence of an unsafe condition due to ground proximity and then issues the proper annunciations.
Systems status shows on the auxiliary EICAS display. The left and the right CMCS receive status information for recording in memory and display on the CDUs.
The GPWS displays terrain forward of the airplane and also alerts the flight crew to early descent when landing. Visual annunciations show on the: - Primary flight display (PFD) - Navigation displays (NDs) - GPWS warning module - Master warning lights Aural annunciations sound from the aural warning speakers. The GPWC sends terrain data to show on the NDs.
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NAVIGATION Ground Proximity Warning System
GPWS - GROUND PROXIMITY MODES The GPWS has seven modes and two terrain alerting and display (TAAD) functions. The graphic shows their descriptions and annunciations.
Modes 1 and 2 are both alert and warning modes. The initial annunciation is an alert. If the condition persists, the respective warning replaces the alert.
The GPWS utilizes two kinds of indications: warnings and alerts. The warnings include:
Modes 3, 4, 5, and 6 are alert-only modes. Mode 7 is a warning-only mode.
- A red indication on the PFD and ND - An aural annunciation - The illumination of the master warnings lights
Terrain alerting and display functions are both warning and alert modes.
The alerts do not include PFD indications and the illuminations of the master warning lights. Instead, they include an aural annunciation and the illumination of the amber GND PROX-G/S INHB light/switch on the GPWS warning module and an amber indication on the ND in all cases except the radio altitude callouts.
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GPWS - COMPONENT LOCATIONS - I The GPWS components in the flight deck are: - Ground proximity warning computer circuit breaker - GPWS warning module The interface components are: - Captain's and first officer's aural warning speakers - Captain's and first officer's master warning lights - Left and right outboard IDUs - Left and right inboard IDUs - Lower IDU
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GPWS - COMPONENT LOCATIONS - 2 The ground proximity warning computer is located in the main equipment center.
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GPWS - ARINC 429 INPUTS Radio Altimeter (RA)
The L ILS receiver supplies:
All three radio altimeters supply radio altitude.
- Glide slope deviation - Localizer deviation - Selected runway heading
The primary source is the L RA. If the L RA fails then the GPWC defaults to the C RA. If both L RA and C RA fail then the GPWC defaults to the R RA.
Flight Management Computer (FMC) The GPWC also compares RA inputs. If the left RA is within 500 feet of the center or right RA then the GPWC uses the left RA. If the left RA fails the comparison, the GPWC will use the center RA if it is within 500 feet of the right RA. If both the left and center RAs fail the comparison, the GPWC will use the left RA.
Air Data Computer (ADC)
The L FMC supplies: - Latitude - Longitude - Magnetic track The primary source is the L FMC. If the L FMC fails, the GPWC defaults to the L IRU.
The input from the L ADC supplies: - Computed airspeed - True airspeed - Baro altitude - Baro corrected altitude - Baro altitude rate Instrument Landing System (ILS)
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Inertial Reference System (IRS) The left inertial reference unit (L IRU) supplies: - Latitude - Longitude Magnetic track - Inertial vertical speed
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Inertial Reference System (IRS) (cont) - Inertial altitude - Pitch angle - Roll angle - Pitch rate - Normal acceleration - Longitudinal acceleration - Inertial vertical acceleration - Attitude mode
Central Management Computer (CMC) The L CMC supplies: - CDU ground test commands - CDU confidence test commands - Status requests
Data Utilization EFIS Control Panel/Control-Display Unit –(EFIS CP/CDU) The left EFIS CP/CDU supplies decision height.
The matrix on appendix 1 COMPUTATION DATA SOURCES at the end of this course shows the utilization of the various parameters.
MAWEA The left and right stall warning cards supply: - Indicated AOA - Corrected AOA - Stick shaker AOA - Flap angle - Minimum operating speed The left stall warning card is the primary source. If it fails, the GPWC defaults to the right stall warning card.
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Global Positioning System (GPS) The left and right multi-mode receivers (MMRs) send this GPS data: - Latitude - Longitude - Altitude - Vertical Speed - Date Time (UTC) - Ground Speed - True Track - GPS data integrity figure - GPS sensor status. Weather Radar (WXR) (OPTIONAL) The WXR receiver transmitters (RTs) send predictive windshear (PWS) data to the GPWC to inhibit lower priority GPWS alerts.
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NAVIGATION Ground Proximity Warning System
GPWS - ANALOG INPUTS Power
This signal indicates one of two states:
Power is 115v ac from the overhead circuit breaker panel.
- Flaps up for flaps at 20 or less - Flaps down for flaps at 25 or 30
Air/Ground Discrete
The flap override switch on the GPWS warning module simulates a flap down position.
The input from the air/ground relays along with computed airspeed and radio altitude determine an in air or on ground condition, which: Landing Gear Position - Disables mode annunciations on the ground - Disables the flight deck tests in flight - Defines flight leg beginning and end in the fault memory, if the CMC is unable to do so.
The computation of some modes also includes landing gear lever position. The source of the landing gear discrete is the landing gear lever switch.
Glide Slope Inhibit Discrete
The configuration/gear override switch on the GPWS warning module simulates a gear down position.
The glide slope inhibit discrete from the GND PROX-G/S INHB light/ switch on the GPWS warning module inhibits or cancels mode 5.
Landing Flap Position The computation of some modes includes landing flap position. The source of the landing flap discrete is the center or left flap control unit.
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Terrain Override Switch Pressing the terrain override switch (TERR OVRD) overrides the terrain clearance floor (TCF) and terrain awareness alerting and display (TAAD) features. GPWS modes 1-7 will continue to function after the TCF and TAAD features are inhibited by this switch.
Program Pins GPWC program pins define various options available to the airlines. The program pins are read when the GPWC is powered ON. The program pin configuration determines parameters such as: - Airplane type - Mode 6 altitude callouts - High or low audio volume. The program pin common is inside the GPWC.
Terrain Relay Monitor The terrain relay monitor gives the GPWC the position of the Capt and FO terrain relays and shows if the actual relay position matches the commanded position.
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GPWS - ANALOG OUTPUTS
MAWEA Outputs
GPWC-Analog-Output-signals
The MAWEA transmits its outputs in this way: Aural annunciations from the left aural synthesizer card to the captain's aural warning speaker.
The analog output signals are: - Aural annunciations - PULL UP warning discrete (modes I and 2) - WINDSHEAR warning discrete (mode 7) - Modes I thru 5 alert discrete - Glide slope cancel discrete - Aural prioritization discretes - Terrain display discretes.
- Aural annunciations from the right aural synthesizer card to the first officer's aural warning speaker. - Discretes from both master monitor cards to both master warning lights.
The GPWC produces the aural annunciations. The synthesizer cards in the MAWEA amplify them. The pull up warning, windshear warning, and alert discretes go to the TCAS (traffic alert and collision avoidance system) computer to inhibit lower priority TCAS alerts. Aural prioritization discretes go to TCAS and the weather radar(OPTIONAL) to inhibit lower priority aural alerts.
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GPWS - DIGITAL BUS OUTPUTS ARINC 429 The ARINC 429 outputs from the GPWC are: - Pull-up warning (modes 1 and 2) - Windshear warning (mode 7) - GPWS status (GPWS function failure) - Windshear status (windshear function failure) - Status data for the CMC The EFIS/EICAS Interface Units (EIUs) receive the above ARINC 429 DATA and then transmit the signals to the primary flight displays, EICAS displays and CMCs.
ARINC 453 Terrain display data is sent on two high speed ARINC 453 data buses from the GPWC. These data buses go to the terrain switching relays along with weather radar (WXR) display data. Either terrain or WXR data is sent to the navigation displays. Logic in the GPWC controls the position of the terrain switching relays.
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NAVIGATION Ground Proximity Warning System
GPWS - GROUND PROXIMITY WARNING COMPUTER Purpose
Front Panel
The ground proximity warning computer (GPWC) compares the airplanes flight profile, flap and gear position, and terrain clearance to determine if an alert condition exists.
The GPWC front panel has three status LEDs and a door. These are the three status LEDs on the front panel:
Description The enhanced GPWS function contains a worldwide terrain database. It compares airplane position, track and speed with this database to determine if an alert condition exists. Terrain data displays on the navigation displays (NDs).
- EXTERNAL FAULT - amber LED turns on for a failure external to the GPWC. - COMPUTER OK - green LED stays on when GPWC has power and operates normally. - COMPUTER FAIL - red LED turns on when the GPWC has an internal failure.
The enhanced GPWS function also contains an airport database. This database contains terrain information about all hard surface runways 3500 feet or more in length. GPWS compares airplane position and runway location to determine if an alert condition exists.
Physical Description The ground proximity warning computer (GPWC) is a two MCU chassis and weighs seven pounds. The GPWC requires no forced cooling air.
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Front Panel (cont) The front panel door allows access to the following: - PRESS TO SELF TEST switch - begins a test of the GPWS - Headphone jack - allows you to hear self test audio - Memory card slot - allows you to upload software from a memory card, or download fault and warning history data - Upload/download status indicators -displays conditions of upload or download operation - RS-232 connector - used for shop test, or for the upload/ download of data.
Voice Menu Configuration Several aural message configurations are available. Selection of the desired configuration is by grounding the appropriate program pins. CAUTION: STATIC SENSITIVE. DO NOT HANDLE BEFORE READING PROCEDURE FOR HANDLING ELECTROSTATIC DISCHARGE SENSITIVE DEVICES (REF 20-41-02/201). CONTAINS DEVICES THAT CAN BE DAMAGED BY STATIC DISCHARGE.
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NAVIGATION Ground Proximity Warning System
GPWS - CONTROL COMPONENTS Description
Flap and Gear override Switches
The GPWS warning module contains the system control components. It is a self-contained unit and therefore it a Line Replaceable Unit (LRU). The module contains these controls:
The GND PROX FLAP OVRD switch and the GND PROX CONFIG GR OVRD switch simulate flaps down 25 units or more and landing gear down positions. These are guarded alternate-action pushbutton switches.
- A ground proximity glide slope inhibit light/switch - A ground proximity flap override switch - A ground proximity configuration/ gear override switch - Terrain override switch.
In the ON position the switches illuminate.
GND PROX – G/S INHB Light/Switch The GND PROX-G/S INHB light/switch has two functions: - The GND PROX light shows ground proximity alerting for modes 1 through 5. - Push the switch to inhibit or cancel mode 5 (below glide slope) visual and aural alerts. If the operator pushes the switch before the mode 5 indications start, then mode 5 is inhibited. If the operator pushes the switch after the indications have started, then all mode 5 indications are cancelled. After this inhibit or cancel action, a second push of the switch cannot re-start mode 5. To reset mode 5, the airplane must descend below 30 ft or ascend above 1000 ft RA.
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Terrain override Switch Push the TERR OVRD switch to inhibit the terrain clearance floor (TCF) and terrain awareness and alerting display (TAAD) functions of the GPWS. The basic modes (modes 1-7) of the GPWS are not affected by this switch. The flight crew uses the terrain override switch for any of the following conditions: - The crew determines position data is not valid. - A terrain awareness alert shows when it is obvious no terrain threats exist. CAUTION : CAREFULLY SLIDE GROUND PROXIMITY WARNING MODULE OUT OF INSTRUMENT PANEL TO AVOID STRESS AND/OR DAMAGE TO ELECTRICAL CABLE AT REAR OF THE GROUND PROXIMITY WARNING MODULE.
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GPWS - PFD AND MASTER WARNING LIGHT ANNUNCIATIONS
PFD Warning Annunciations The red PULL UP annunciation on the PFD indicates a mode 1 warning or a mode 2 warning. The red WINDSHEAR annunciation on the PFD indicates a mode 7 warning.
Master Warning Lights The captain's and first officer's master warning lights illuminate during the PULL UP and WINDSHEAR warnings.
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NAVIGATION Ground Proximity Warning System
GPWS - MODE 1 DESCRIPTION Mode 1 Definition Mode 1 supplies alerts and warnings of a large descent rate with respect to terrain clearance.
Mode 1 Thresholds The threshold of annunciations varies with descent rate. The threshold value is 2450 ft RA for descent rates of 5007 feet per minute (FPM) and greater. For lower descent rates the threshold value is lower. At 30 ft RA, there are no annunciations if the descent rate is less than 998 FPM. The lower boundary of annunciation is 30 ft.
The alert consists of these indications: - The GND PROX-G/S INHB light/switch shows - The aural message "sink rate.... “ is repeated. To prevent nuisance alerts during an ILS approach, the initial envelope will be modified when the airplane is above the Glide Slope. The amount of linear modification will be 0 FPM when on Glide Slope to a maximum of 300 FPM when the airplane is 2 dots above Glide Slope. If the descent rate does not decrease, the warning follows. The warning consists of these indications: - The red PULL UP message on the PFDs - The red master warning lights - The aural message "whoop whoop pull up... “ is repeated.
This mode functions independently o landing gear and flap positions.
Mode Annunciations Mode I includes two levels of annunciations: - An alert - A warning.
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NAVIGATION Ground Proximity Warning System
GPWS - MODE 1 OPERATION Data Sources
Alert Output
The following LRUs supply these parameters.
The AURAL-7 discrete starts the alert annunciations. It closes switch S1 which:
Left, center or right radio altimeter supplies radio altitude - Turns on the GND PROX-G/S INHB light/switch. Left IRU supplies inertial vertical speed Left ILS supplies glide slope deviation Left or right ADC supplies baro altitude rate.
- Goes to the traffic alert and collision avoidance system (TCAS) to inhibit advisories. It also goes to the speech prom which generates the aural SINK RATE.
Inertial vertical speed is the primary parameter. If it is not available, the mode detector uses baro altitude rate. Warning Output Mode 1 Function The mode 1 detector determines a presence of mode 1 and generates the required annunciations which are: - A preliminary annunciation which is an alert - A warning.
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The AURAL-1 discrete: - Goes to the speech prom which generates the aural WHOOP, WHOOP PULL UP - Closes switch S2 which causes the MAWEA to turn on the master warning lights and the TCAS to inhibit advisories - Goes to the EIUs to show the red warning PULL UP on the PFDs.
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Aural Output The speech prom generates the aurals. The audio amplifier amplifies them and transmits them to the MAWEA via an output transformer. The MAWEA then sends them for transmission over the captain's and the first officer's aural warning speakers.
Mode Variations The envelope modulation circuit supplies mode boundary variations at specific locations. The BITE circuit supplies mode inhibit commands when circuit or input failures are present.
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NAVIGATION Ground Proximity Warning System
GPWS - MODE 2A DESCRIPTION Mode 2 Definition
Mode 2A Annunciations
Mode 2 supplies alerts and warnings for too large of a closure rate with respect to rising terrain. Mode 2 has two variations, 2A and 2B.
Mode 2A includes two levels of annunciations:
Mode 2A applies when the airplane is not in a landing configuration, that is if the flaps are 20 units or less and the glide slope deviation is greater than 2 dots. Mode 2B applies when the airplane is in a landing configuration, that is if the flaps are 25 or 30 units, or if the airplane is on an ILS approach with glide slope deviation of 2.0 dots or less.
Mode 2A Thresholds
- An alert - A warning. The alert consists of these indications: - The GND PROX-G/S INHB light - The aural alert message "TERRAIN, TERRAIN". After two alert messages, if the closure rate does not decrease, the warning follows.
The threshold of annunciations varies with CAS and closure rate. These are typical threshold values: - 2450 ft RA for CAS values of 310 knots (KTS) or greater and closure rates of 9800 FPM or greater - 1650 ft RA for CAS values of 220 KTS or less and closure rates of 5733 FPM or greater. The lower boundary of annunciations is 30 ft.
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Mode 2A Annunciations (cont) The warning consists of these indications: - The red PULL UP message on the PFDS - The red master warning lights - The aural message "WHOOP WHOOP PULL UP. . . “ is repeated.
Altitude Gain Function If the mode 2A warning envelope has been entered for more than 3 seconds and the sink rate condition has been corrected, the GPWC checks the landing gear position. If the gear is up, the altitude gain function is started. When the sink rate condition is corrected, the GPWC switches back to the 2A alert visual indications (GND PROX G/S INHB light) and shuts off the "TERRAIN" aural as long as there is no further terrain closure. This alert indication will continue until the airplane has gained 300 feet altitude up to a maximum of 45 seconds, or the landing gear is lowered. If the gear is down the altitude gain function is inhibited.
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GPWS - MODE 2B DESCRIPTION Mode 2B Annunciations Mode 2B has two variations of annunciations: - When the airplane is in landing configuration; gear and flaps down - When the airplane is not in landing configuration; flaps or gear up, or both up.
If the condition continues, the annunciation changes to this: - The aural WHOOP, WHOOP PULL UP, is repeated - The red PULL UP message shows on th PFDs - The master warning lights show.
Mode 2B Thresholds Airplane in Landing Configuration The annunciation has these indications: - The aural TERRAIN, TERRAIN, is repeated - The GND PROX-G/S INHB light.
Airplane Not in Landing Configuration The annunciation shows this first:
The threshold of annunciations varies with closer rate. It is 789 ft for closure rates of 3000 FPM or greater. For lower closure rates the threshold values are lower. For instance, for a closure rate of 2253 FPM the threshold value is 200 ft. When the flaps are down, the lower boundary, at which the annunciations cease varies with descent rate. It is 200 ft for descent rates of 400 FPM and less, and 600 ft for descent rates of 1000 FPM or more. For descent rates between 400 FPM and 1000 FPM, the lower boundary varies linearly. When the flaps are up, the lower boundary is 30 ft.
- The aural TERRAIN, TERRAIN once - The GND PROX-G/S INHB light.
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NAVIGATION Ground Proximity Warning System
GPWS - MODE 2 OPERATION Mode 2 Function The mode 2 detector determines a presence of modes 2A and 2B and generates the required annunciations. Both, mode 2A and 2B, include a preliminary annunciation which is an alert, and after that a warning. When the airplane is in landing configuration, mode 2B has the continuous alert only. Data Sources
IVS and inertial altitude are the primary parameters. If they are not available, the mode detector uses baro altitude rate and baro altitude.
The following LRUs supply these parameters.
The landing gear lever switch supplies landing gear lever position.
Left, center or right radio altimeter supplies radio altitude. The GPWC computes closure rate from radio altitude.
The left and center flap control units supply flap position.
The left ILS supplies glide slope deviation, localizer deviation and selected runway heading.
GPWS warning module supplies: Left inertial reference unit supplies: - Inertial vertical speed (IVS) - Inertial altitude - Magnetic track.
- Simulated gear lever down position - Simulated flaps down position. The left FMC supplies magnetic track.
Left or right air data computer supplies: - Baro altitude rate - Baro altitude - Computed airspeed.
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NAVIGATION Ground Proximity Warning System
Alert Output
Mode Variations
The aural -2 discrete closes switch S1 and turns on the GND PROX-G/S INHIBIT light/switch. It goes to the speech prom which generates the aural "TERRAIN".
The envelope modulation circuit supplies mode boundary variations in specific locations. The BITE circuit supplies mode inhibit commands when circuit or input failures are present. An output from the AIR/GROUND logic circuit inhibits all mode annunciations on the ground.
The discrete from switch S1 goes to TCAS to inhibit TCAS advisories.
Warning Output The aural -1: - Goes to the speech prom which generates the aural "WHOOP, WHOOP PULL UP" - Closes switch S2 which causes the MAWEA to turn on both master warning lights and inhibits TCAS advisories - Goes to the EIUs to show the red warning PULL UP on the PFDs.
Aural Output The speech prom generates the aurals. The audio amplifier amplifies them and transmits them to the MAWEA via an output transformer. The MAWEA sends them for transmission over the captain's and the first officer's aural warning speakers.
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NAVIGATION Ground Proximity Warning System
GPWS - MODE 3 DESCRIPTION Mode 3 Definition
Mode 3B Threshold
Mode 3 applies to takeoff or missed approach when not in landing configuration, that is when the gear is up and/or the flaps are not 25 or 30. Mode 3 has two variations: 3A and 3B. Mode 3A starts an alert when the airplane has lost a greater amount of altitude than a threshold value. Mode 3B starts an alert when the airplane is closer to the ground than a threshold value.
The mode 3B threshold depends on climb rate and elapsed time since takeoff. It is 150 ft at takeoff and increases with time to-about 75% of altitude gain.
Mode 3B Annunciations Mode 3B, also is an alert-only mode. Its annunciations are:
Mode 3A Threshold - The repeated aural TERRAIN The mode 3A threshold depends on radio altitude and elapsed time after take off. It is roughly 10% of RA for high climb rates and 20% for low climb rates.
- The illumination of the GND PROX-G/S INHB light/switch. The annunciations stop when the airplane climbs above the mode 3B threshold value.
Mode 3A Annunciations Mode 3A is an alert-only mode. Its annunciations are:
In a case of conflict, mode 3B annunciation takes precedence over the mode 3A annunciation.
- The repeated aural SINK RATE - The illumination of the GND PROX-G/S INHB light/switch The annunciations stop when the airplane stops losing altitude.
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Mode 3 To Mode 4 Transition Modes 3 and 4 are mutually exclusive. When mode 3 is armed, mode 4 is inhibited, and vice-versa. The switchover from mode 3 to mode 4 occurs when the mode 3B threshold reaches the value of the mode 4A threshold.
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NAVIGATION Ground Proximity Warning System
GPWS - MODE 3 OPERATION Mode 3 Function The mode 3 detector determines a presence of mode 3 and generates the required annunciations.
IVS and inertial altitude are the primary parameters. If they are not available, the mode detector uses to baro altitude rate and baro altitude.
Mode 3 is an alert-only mode. The landing gear lever switch supplies landing gear lever position. Data Sources
The left and center flap control units supply flap position.
The following LRUs supply these parameters for the computation of mode 3 annunciations.
GPWS warning module supplies:
The left, center or right radio altimeter supplies radio altitude.
- Simulated gear lever down position - Simulated flaps down position.
Left inertial reference unit supplies: Mode outputs - Inertial vertical speed (IVS) - Inertial altitude. Left or right air data computer supplies: - Baro altitude rate - Baro altitude.
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Both the aural -6 and -2 outputs: - Close switch S1 which turns on the GND PROX-G/S INHB light/ switch and inhibits TCAS advisories - Go to the speech prom to generate the aural -6, "SINK RATE", and aural -2, "TERRAIN".
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NAVIGATION Ground Proximity Warning System
Aural Outputs
Mode 4 to Mode 3 Switchover
The speech prom generates the aurals. The audio amplifier amplifies them and transmits them to the MAWEA via an output transformer. The MAWEA sends them for transmission over the captain's and first officer's aural warning speakers.
The switchover occurs during landing. When the airplane descends through the low-airspeed mode 4B boundary (at 245 ft) with gear and flaps down, mode 4 detector arms mode 3 and disables mode 4.
Mode-inhibit
If at the low-airspeed mode 4B boundary (at 245 ft) the gear and/or the flaps are up, the mode 4 to mode 3 switchover occurs when the airplane descends through 30 ft RA.
The BITE circuit supplies mode inhibit commands when circuit or input failures are present.
Mode 3 to Mode 4 Switchover The switchover occurs during take-off when the mode 3B threshold reaches the value of the mode 4A threshold. Mode 3 detector arms mode 4 and disables mode 3.
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GPWS - MODE 4 DESCRIPTION Mode-4 Definition
Mode 4 Thresholds
Mode 4 supplies alerts when the airplane is too close to terrain and not in landing configuration. (Landing configuration is: gear and flaps down, that is flaps at 25 or 30). Mode 4 has two variations: Mode 4A and mode 4B. Mode 4A applies when the landing gear is up. Mode 4B applies when the landing gear is down.
The threshold of the low-airspeed annunciation TERRAIN in mode 4A is 500 ft RA for airspeeds up to 190 knots.
Mode-_Annunciations Each one, mode 4A and mode 4B, has two variations of annunciations, which depend on computed airspeed (CAS).
The threshold of the low-airspeed annunciation TERRAIN in mode 4B is 245 ft RA for airspeeds up to 159 knots. For higher airspeeds, the threshold increases to 1000 ft at 250 knots. Above 250 knots, the threshold value stays at 1000 ft. The upper boundry is revised to 800 feet for 60 seconds following a detection of exccessive rate. This helps prevent false warnings when over flying other aircraft. The lower boundary of annunciations is 30 ft.
At low airspeeds the annunciations are: - For mode 4A: TERRAIN, - For mode 4B: TERRAIN.
When the flaps are down, the mode 4A threshold is 500 ft RA at all airspeeds.
At high airspeeds, the annunciation is TERRAIN for both modes 4A and 4B. The visual annunciation in all cases is the illumination of the GND PROX-G/S INHB light/switch.
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NAVIGATION Ground Proximity Warning System
GPWS - MODE 4 OPERATION Mode 4 Function The mode 4 detector determines a presence of mode 4A or 4B and generates the required annunciations.
- Aural 2: "TERRAIN"
The modes 4A and 4B are alert-only modes.
When switch S1 closes, a discrete goes to TCAS to inhibit TCAS advisories.
Data Sources
Aural
The following LRUs supply these parameters for the computations of modes 4A and 4B:
The speech prom generates the aural. An audio amplifier amplifies this and transmits it to the MAWEA via an output transformer. The MAWEA sends the aural to the captain's and first officer's aural warning speakers.
- L, C or R RA supplies radio altitude - Left or right ADC supplies computed airspeed (CAS) - Landing gear lever switch supplies landing gear up or down position - C or L FCU supplies flap position - GPWS warning module supplies simulated gear down and/or or flap down.
Mode 4 Variations The envelope modulation circuit supplies mode boundary variations in specific geographic locations.
Mode 4 Outputs The mode 4 detector turns on the GND PROX-G/S INHB light/switch when switch S1 closes. One aural output discrete, aural-2, generates in the speech prom the aural:
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Mode 4 Variations (cont) The BITE circuit supplies mode inhibit commands when circuit or input failures are present. An output from the AIR/GND logic circuit inhibits all mode annunciations on the ground.
Mode 4 to Mode 3 Switchover A mode 4 to mode 3 switchover occurs during landings. When the airplane descends through the low-airspeed mode 4B boundary (at 245 ft) with the gear and flaps down, the mode 4 detector arms mode 3 and disables mode 4. If at the low-airspeed mode 4B boundary (at 245 ft) the gear and/or flaps are up, the mode 4 to mode 3 switchover occurs when the airplane descends through 30 ft radio altitude.
Mode 3 to Mode 4 Switchover The mode 3 to mode 4 switchover occurs during take-off. The mode 3 detector arms mode 4 and disables mode 3 when the mode 3B threshold reaches the value of the mode 4A threshold.
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GPWS - MODE 5 DESCRIPTION Mode 5 Definition and Annuciations
Aural Sound-Levels
The mode 5 envelope limits are determined by monitoring radio altitude and deviation below the glide slope.
Mode 5 has two sound levels:
Mode 5 indications can occur between 1000 feet down to 30 feet RA. Mode 5 is armed when the airplane descends below 1000 feet RA, the landing gear is down and the localizer is captured (within 2 dots) before descending below 500 ft. Mode 5 is an alert-only mode. Mode annunciations are: - The repeated aural "GLIDE SLOPE" at different repetition rates and sound levels, and - The illumination of the GND PROX-G/S INHB light/switch.
Aural Repetition Rate
- Below 1000 ft RA with a glide slope deviation greater than 1.3 dots (below glide slope), the aural "GLIDE SLOPE" is at half volume. - Below 300 ft RA with a glide slope deviation greater than 2 dots (below glide slope), the aural "GLIDE SLOPE" is at normal level.
Mode 5 Inhibit or Cancellation The GND PROX-G/S INHB light/switch inhibits or cancels mode 5 below 1000 ft RA nominal. If mode 5 is not in operation, a push on the switch inhibits any future mode 5 annunciations. If mode 5 is in operation, a push on the switch cancels any visual and aural annunciations. It is not possible to rearm mode 5 by another push on the switch. To rearm mode 5, the airplane must either descend below 30 ft RA or ascend above 1000 ft RA.
The repetition rate of the glide slop aural is increased as the terrain clearance decreases and/or the glide slope deviation increases.
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NAVIGATION Ground Proximity Warning System
GPWS - MODE 5 OPERATION Mode 5 Function
Mode Outputs
The mode 5 detector determines the presence of mode 5 and generates the required annunciations.
The aural 9 output:
Data Sources
- Closes switch SI, turns on the GND PROX-G/S INHB light/switch, and inhibits WAS advisories - Goes to the speech prom to generate the GLIDE SLOPE aural
Mode 5 inputs are: Aural Output - Radio altitude from the left, center or right radio altimeter - Glide slope and localizer deviation and selected runway heading from the left ILS receiver - Magnetic track from the left FMC (primary source) - Magnetic track from the left IRU (alternate source) - Landing gear lever switch position - Glide slope inhibit discrete from the GPWS warning module - Simulated gear lever down position from the configuration gear override switch
The speech prom generates the aural. The audio amplifier amplifies it and sends to the MAWEA via the output transformer. The MAWEA sends the aural to the captain's and first officer's aural warning speakers.
Heading Compare The backcourse compare circuit inhibits mode 5 annunciations during backcourse. The airplane is in backcourse when the angle between selected runway heading and magnetic track is greater than 90 degrees.
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NAVIGATION Ground Proximity Warning System
Repetition Rate
Mode Variations
Based on radio altitude and glide slope deviation, the G/S voice repetition rate circuit adjusts the repetition rate of the aural annunciation.
The envelope modulation circuit supplies mode boundary variations in specific locations. The BITE circuit supplies mode inhibit commands when circuit or input failures are present.
Sound Levels The mode 5 detector reduces the amplifier gain to half volume when the airplane: - Glide slope deviation is less than two dots, and/or - RA is not below 300 feet
Mode 5 Inhibit or cancellation The GND PROX-G/S INHB light/switch inhibits or cancels mode 5 below 1000 feet radio altitude.
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GPWS - MODE 6 DESCRIPTION Mode 6 Definition
Mode 6 Reset
An optional GPWC feature is mode 6 aural callouts. This mode does not give visual displays. One or more pin selections determine the RA callout configuration.
Mode 6 callouts sound only once. To repeat the callouts sequence, the airplane must ascend above 1000 feet radio altitude.
Volume RA Callout Selection The present radio altitude aural callout configuration selected produces the aural messages shown when the airplane descends through these pre-determined radio altitudes:
The volume of the callouts is one quarter of the level of the other modes.
- FIVE HUNDRED at 500 feet - ONE HUNDRED at 100 feet - FIFTY at 50 feet - FORTY at 40 feet - THIRTY at 30 feet - TWENTY at 20 feet - TEN at 10 feet - MINIMUMS at DH setting BANK ANGLE BANK ANGLE sounds when the roll angle exceeds 40 degrees at all altitudes above 150 feet. The alert sounds when the roll angle increases by 20 percent.
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NAVIGATION Ground Proximity Warning System
GPWS - MODE 6 OPERATION Mode 6 Function
Mode Outputs
The mode 6 detector generates the selected radio altitude callouts at predetermined radio altitudes.
The radio altitude callout aural discretes go to the speech prom to generate the aurals.
Data Sources Mode 6 inputs are: - Radio altitude from the left, center or right RA - Roll angle from the left IRU - Landing gear lever position - Simulated gear lever down position from the configuration gear override switch.
Program Pins
The audio amplifier amplifies them to one quarter normal volume (LO VOLUME) and sends them to the MAWEA via the output transformer. The MAWEA sends them to the captain's and first officer's aural warning speakers. Mode six does not include the illumination of the GND PROX-G/S INHB light/switch.
Mode 6 Reset Each of the mode 6 annunciations can sound only once. To reset the mode 6 function, the airplane must climb above 1000 feet.
The program pin RA CALLOUT ENABLE enables the mode 6 function. Various program pins define the RA callout configuration. The RA CALLOUT LO VOLUME program pin reduces the volume of the callout to one-quarter of normal level.
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Mode 6 Reset (cont) Above 150 feet the alert "BANK ANGLE -BANK ANGLE" sounds at 40 degrees of roll angle measured by the left IRU. The alert sounds at 10 degrees of roll angle at 30 feet. The alert set point increases to 40 degrees at 150 feet. The alert repeats for each 20 percent increase in roll angle.
Mode Variations The envelope modulation circuit removes the gear down requirement in specific locations. The BITE circuit supplies inhibit commands when circuit or input failures are present.
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GPWS - MODE 7 DESCRIPTION Reactive Windshear Detection An optional GPWC feature is mode 7 reactive windshear detection. Windshear can happen anywhere in the atmosphere. It can have both horizontal and vertical components, and consists of large volumes of air which move quickly in different (usually opposite) directions.
The windshear warning annunciations continue as long as the windshear condition exists and the indicated AOA is within four degrees of stick shaker AOA, but no less than five seconds. The GPWC inhibits all other GPWS modes during a windshear warning.
One type of windshear which is most dangerous to airplanes is the microburst, which has a column of downward-moving air. Microbursts are most dangerous below 500-feet, where pilots have little time and airspace to recover. The graphic shows a microburst situation on approach.
Warnings Mode 7 produces a warning for a windshear condition during takeoff or final approach, below 1500 feet radio altitude. A windshear warning includes these annunciations: - A siren sounds followed by the repeated aural message "windshear, windshear, windshear”, - A red WINDSHEAR warning message shows on the PFDs. - The master warning lights come on.
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GPWS - MODE 7 OPERATION Mode 7 Function The mode 7 detector computes a vertical and a horizontal windshear component, that combine to yield a total windshear indication, in takeoff or in approach. The detector compares this windshear indication to thresholds which are a function of approach/takeoff flap position. If the windshear indication exceeds the threshold, the mode 7 detector issues a warning.
Left and right stall warning cards in the MAWEA supply: - Indicated angle of attack (AOA) - Corrected angle of attack - Stick shaker angle of attack - Flap angle
Minimum operating speed. Data Sources The following LRUs supply these parameters for the computation of the windshear indication. Left, center or right radio altimeter (L, C or R RA) supplies radio altitude. Left inertial reference unit (L IRU) supplies:
The left stall warning card is the primary source. If it fails, the mode detector uses data from the right stall warning card. The right ADC and the left or center ADC supplies: - True airspeed (TAS) - Computed airspeed (CAS). Center flap control unit (C FCU) or left FCU supplies flap position of 25 units or greater.
- Inertial vertical speed - Pitch angle - Pitch rate Roll angle - Longitudinal acceleration - Normal acceleration - Vertical acceleration - Attitude mode.
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Program Pins
Mode Inhibit
Program pins enable the mode 7 function and select the airplane type (747-400).
The BITE circuit issues mode inhibit commands when circuit or input failures are present.
Mode Outputs The aural-10 discrete issues the windshear warnings. It: - Causes the speech prom to generate the repeated aural-10 WINDSHEAR... - Closes switch S3 which inhibits TCAS advisories and causes the MAWEA to turn on both master warning lights - Causes the EIUs to show the red message WINDSHEAR on the PFDs.
Aural Outputs The speech prom generates the aural WINDSHEAR. The audio amplifier amplifies it and transmits it to the MAWEA via an output transformer. The MAWEA sends the aural for transmission over the captain's and first officer's aural warning speakers.
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NAVIGATION Ground Proximity Warning System
GPWS - TERRAIN AWARENESS FUNCTION Purpose
Terrain Awareness Calculation
The ground proximity warning computer (GPWC) compares the airplane flight profile, flap and gear position, and terrain clearance to determine if an alert or warning condition exists.
The GPWC stores a world-wide terrain database in memory. The GPWC looks at airplane position and track, and compares this data to the terrain database. If the GPWC determines there is a terrain threat, it makes an alert.
Terrain Awareness Inputs Terrain Display Output The GPWC receives airplane data from the air data computers (ADC), inertial reference system (IRS), Flight Management Computer Left and the global positioning system (GPS). The terrain awareness function uses this data:
The GPWC makes a digital map of the terrain forward of the airplane. It sends this digital map to the navigational displays (NDs). The display uses different colored dots to show terrain altitude relative to airplane altitude.
- Latitude - Longitude - Barometric altitude - Ground track - Ground speed - Heading - Roll attitude - Flight path angle (calculated by GPWC). Terrain awareness uses GPS for latitude and longitude.
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Terrain Alert Outputs If the GPWC determines the airplane is about 60 seconds from a terrain conflict, it makes a terrain caution alert. The caution alert is as follows: - Alert aural message CAUTION TERRAIN - Amber message TERRAIN shows on the ND - The terrain display shows on both NI)s if not selected on either one - The threat terrain on the ND changes from dots to a solid yellow color - The ground proximity warning light comes on. If the GPWC determines the airplane is about 30 seconds from a terrain conflict, it makes a terrain warning alert. The warning alert is as follows: - Aural message TERRAIN, TERRAIN PULL UP - A red PULL UP message shows on the primary flight display (PFD) - A red TERRAIN message shows on the ND - The terrain display shows on both NDs if not selected on either one - The terrain threat on the ND changes from dots to a solid red color - The master warning lights come on.
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NAVIGATION Ground Proximity Warning System
GPWS - TERRAIN CLEARANCE FLOOR Description
Terrain Clearance Floor Logic
Terrain clearance floor (TCF) alerts the flight crew when the airplane descends too low on approach. TCF uses airplane position and a runway database to determine if an alert condition exists.
The GPWC stores a runway database in memory. This database contains the location of all hard surface runways in the world that are 3,500 feet or more in length. TCF makes a terrain clearance envelope around the runway. The altitude of the envelope increases as the distance from the airport increases. GPWC compares airplane latitude, longitude, and radio altitude with TCF envelope data. If the airplane descends through the floor of the envelope, GPWC makes an alert.
Terrain Clearance Floor Inputs The ground proximity warning system (GPWS) receives airplane data from these systems:
TCF makes an alert even if the airplane is in landing configuration. - Global positioning system (GPS) - Air data computers (ADCs) - Inertial reference system (IRS) - Radio altimeters (RA). TCF uses this data: - Latitude - Longitude - Radio altitude. TCF uses GPS for latitude and longitude. It uses IRS data if GPS data is not valid.
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Terrain Clearance Floor Caution Alert If the GPWC determines the airplane is below the TCF, it makes this caution alert: - Aural message TOO LOW TERRAIN. This message repeats for each 20 percent loss of altitude. - The ground proximity warning light comes on and stays on until the airplane climbs above the TCF. There is no TCF warning alert. The GPWC inhibits TCF alerts for any of these conditions: - Airplane is on the ground - Less than 20 seconds after takeoff - Less than 30 feet radio altitude.
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NAVIGATION Ground Proximity Warning System
GPWS - ENVELOPE MODULATION DESCRIPTION Purpose
Mode Modulations
Envelope modulation modifies specific alert and warning thresholds in localities with marginal ground proximity terrain conditions.
The present graphic lists the modes that can be modulated and the purpose. In the case of modes 1, 2, and 4, modulation reduces the margin of safety and thus prevents nuisance annunciations. In mode 5, envelope modulation raises the radio altitude thresholds and removes the gear-down requirement which enable annunciations at higher altitudes. In mode 6, the modulation removes the gear-down requirement.
Envelope modulation: - Prevents mode 1, 2, and 4 nuisance annunciations. - Allows mode 5 annunciations, at higher altitudes with the gear not down. - Allows mode 6 annunciations with the gear not down. This function applies to over 100 locations around the world.
Method Envelope modulation takes place only in specifically defined locations and conditions. The GPWC uses latitude and longitude to determine the location of the airplane. The GPWC then uses parameters such as radio altitude, magnetic track, glide slope deviation, runway heading, baro corrected altitude and/or localizer deviation to determine that the airplane is in exactly defined conditions that call for the modulation of the thresholds. The parameters that must have specified values are called the KEY. When the KEY is correct, the GPWC modifies the respective mode thresholds.
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GPWS - ENVELOPE MODULATION OPERATION Envelope Modulation Function
Other Data Sources
The envelope modulation module contains a look-up table that lists all the locations by latitude/longitude that require envelope modulation. The airplane's latitude and longitude is continuously monitored. When the airplane enters an area that requires modulation, the module checks to see if the airplane parameters correspond to the modulation KEY in the look-up table. if the parameters match, modulation proceeds at a predetermined schedule.
In addition to the data from the GPS receivers and the left PMC, these parameters are required for the determination of the modulation KEY: - Glide slope deviation, localizer deviation, and selected runway heading from the left ILS receiver - Radio altitude from the left, center or right RA - Barometric corrected altitude from the right ADC, and the left or center ADC - Magnetic track from the left FMC, or the left or right IRU.
Position Data The left GPS is the primary source of latitude, and longitude. If the left GPS is not available, the modulation module defaults to the right GPS, then to the left FMC.
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Mode Detector Modulation When the modulation module determines the modulation requirements, signals are sent to the respective mode detectors. The mode detectors modify the threshold values and/or remove the gear-down requirement for the various ground proximity modes that are present.
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NAVIGATION Ground Proximity Warning System
GPWS - POWER AND ANALOG INPUTS
Flap and Landing Gear Position
Air/Ground Logic
Discretes that show flap and landing gear positions either arm or inhibit certain modes.
The input from the air/ground relays plus computed air speed and radio altitude define an IN-AIR or an ON-GROUND condition. The transition from ON-GROUND to IN-AIR occurs when the air/ground relays show IN-AIR (contacts closed) and radio altitude is five feet or more. If the relays mistakingly show ON-GROUND (contacts open), the transition occurs when the airspeed is 90 knots or more and the radio altitude is five feet or more.
These are the input sources for the flap discrete: - The center flap control unit - The left flap control unit - The ground proximity flap override switch. These are the input sources for the landing gear discrete:
The transition from IN-AIR to ON-GROUND occurs when the airspeed is 60 knots or less and the radio altitude is one foot or less.
- The landing gear lever switch - The ground proximity configuration/ gear override switch. To simulate flaps-down and gear-down positions, push the override switches on the GPWS warning module. They simulate a flaps-down (25 units or greater) and a landing-gear-down condition, respectively.
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Air/Ground Logic (cont)
Program Pins
The Air/Ground logic does this:
There are 26 program pin inputs to the GPWC. These are some of the selections for your airplane:
- inhibits modes 2 and 4 on the ground - Inhibits flight deck tests in the air - Defines the start and end of a flight leg in fault memory.
28v DC-Signal Input The positions of the Capt and F/O terrain display relays are sent to the GPWC as a 28v dc relay monitoring discrete.
Terrain Display override
- TRIPLE RA SELECT; enables the GPWC to process one of three radio altimeter inputs. - A/P type; identifies the 747-400 - WINDSHEAR ENABLE; enables the mode 7 windshear warning - WINDSHEAR CAUTION DISABLE; disables the windshear caution function - RA CALLOUT ENABLE; enables the radio callout, configuration defined by the RA CALLOUT SELECT program pins - MODE 6 LOW VOLUME; reduces the volume of the RA callouts to a quarter of normal level - The CMC ENABLE program pin allows the use of the data received on the ARINC 429 CMC input bus.
The terrain override switch on the GPWS warning module sends a discrete to the GPWC to override the terrain awareness and alerting display.
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> -
> -
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NAVIGATION Ground Proximity Warning System
GPWS - TERRAIN SELECT RELAY INTERFACE Purpose
Relay Control
The ground proximity warning computer (GPWC) and the weather radar (WXR) receiver-transmitters (RTs) send display data that shows on the navigational displays (NDs). Four terrain select relays control which data shows on each ND.
Relay Power
With weather radar selected, the normal relay position lets weather radar data show on the NDs. When you select TERR on either EFIS control panel (CP), a terrain select ground signal energizes the two on-side terrain select relays. This allows the terrain data to show on the on-side display. Push the TERR switch again and the on-side relays deenergize. The display then shows weather radar data, if selected.
The terrain select relays gets 28v dc from the TERRAIN DISPLAY circuit breaker on the P7 overhead circuit breaker panel.
Relay Monitor The GPWC monitors the terrain select relay positions for faults.
Relay Interfaces The GPWC connects to all terrain select relays with ARINC 453 terrain display data buses. The WXR RTs connect to all terrain select relays with weather display data buses. The terrain select relays connect to the NDs with data buses.
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GPWS - EFIS CONTROL PANEL Description The EFIS control panel provides these functions: - Enables the navigation displays (NDs) to show terrain data - Supplies the selection of different ND modes - Supplies the selection of different ranges for terrain data to show on the NDs.
If the mode selector is not in a correct mode when you push the TERR map switch, the terrain display arms. When armed, the terrain display shows as soon as you change the ND selector to a correct mode. The terrain display stays armed even if you push the TERR map switch again. Push the WXR map switch to disarm the terrain display and arm the weather display.
TERR Map Switch
ND Range Selector
When you push the TERR map switch on the EFIS control panel, terrain data shows on the on-side ND. Push the TERR map switch again to remove the display.
The EFIS control panel has a eight position range selector. The range selections are 5, 10, 20, 40, 80, 160, 320 and 640 NM. The map mode displays the range at all times. APP and VOR modes display the range only when TERR or WXR data show.
ND Mode Selector Use the ND mode selector to select an ND mode. The ND modes that show terrain data are: - Expanded APP (approach) mode - Expanded VOR mode - Expanded MAP mode - Centered MAP mode.
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GPWS - BITE FUNCTION OPERATION BITE Functions The GPWC BITE: - Monitors the validity of inputs - Generates internal test commands - Inhibits mode annunciations when an input or a GPWC function impairs the integrity of that mode - Partially or completely inhibits the flight deck test for the same reasons - When commanded by the BITE DECODER, generates the GPWC BITE callouts - Sends EICAS messages through the EIUs
- Flap control units Landing gear lever - All program pins.
Fault Memory BITE stores faults in nonvolatile fault memory by flight legs. An input from the CMC defines the start of the flight legs. If the CMC input fails, the air/ground relay logic circuit define the flight legs.
Inputs Monitored
Mode Inhibit
BITE monitors the inputs from the following systems and LRU's:
If an input or internal function impairs the integrity of a mode, BITE inhibits just that mode. All other modes continue to work.
- CMCS - LRRA - ADCS - ILS - FMCS - IRS - Stall warning cards - CAPT, and FIO EFIS control panels
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Status The CMC continuously sends the command summary word label 227 to the GPWC. This word is a request for status information or a command to run a flight deck test. In response, BITE sends the fault summary word label 350 to the CMC through the EIUs. This word includes detected failures.
Test Inhibit Certain inputs inhibit parts or all the flight deck tests from the flight deck test sequencer.
Air/Ground Logic The air/ground input: - Inhibits flight deck tests in the air - Defines the start and end of a flight leg if the CMC fails.
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GPWS - FLIGHT DECK SELF-TESTS – 1 Flight Deck Self-Test Description The GPWS has two flight deck self-tests: - The CDU confidence test - The CDU ground test. Both tests are the same. They show the same indications. The only difference is the CMC menu used to access the tests. An IN-AIR input from the air/ground relay prevents the self-tests in the air.
CDU Confidence Test To start a CDU confidence test, select CONFIDENCE TESTS on the CDU CMC menu page and push the line select key next to < GPWC. A test precondition screen will show. After completion of this precondition, push the start test LSK. If the GPWS passes the test, the CDU shows PASS opposite GPWC. If there is a fault, the CDU shows FAIL. To get to the CONFIDENCE TEST MSG page, push the line select key next to FAIL. This page gives more details on the failure.
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GPWS - FLIGHT DECK SELF-TESTS – 2 Ground Test To start a GPWC ground test, first access the CMC chapter 34 navigation radios ground test pages on the CDU. Push the LSK next to GPWC. A precondition screen will come up. After completion of this precondition, push the START TEST LSK. This brings up the ground tests main menu and shows "In progress" over GPWC. An input from the air/ground logic inhibits the ground test in flight.
Ground Test Results The word PASS opposite GPWC shows that the system passed the test. The word FAIL shows a failure in the system. Push the LSK next to FAIL to show the GROUND TEST MSG page. This page gives additional data about the test failure.
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GPWS - LEVEL 1 - SELF TEST General
Level One Test Procedure
The ground proximity warning system (GPWS) has six levels of self test. Each level provides different information about the GPWS. The six levels of self test are:
Select ground or confidence test from the central maintenance computer (CMC) to begin a level one test. A level one test first does a test of these configuration conditions:
- 1 - GO/NO-GO operational test - 2 - Current faults - 3 - System configuration - 4 - Fault history - 5 - Alert/warning history - 6 - Discrete input test.
- Program pin parity - Airplane configuration database validity - Airplane type. If the test finds a configuration fault, self test annunciates the fault and self test ends. If the GPWS passes the configuration test, the level one test continues.
Level one is a GOINO-GO operational test. A level one test provides visual and aural annunciations on the flight deck.
Level One Test Preparation These conditions must be true to do a level one operational test of the GPWS: - Airplane on ground - GPWS power on - EFIS ND mode selector in correct mode (expanded VOR, APP, or MAP or centered MAP) - TERR switch on EFIS control panel (CP) selected.
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Training Information Point You can start a level one self test from the front panel of the GPWC, but you cannot see the flight deck annunciations. Use the CMC to start a test of the GPWS.
- Master warning lights on, PFD message PULL UP (red), and aural message PULL UP - Master warning lights on, PFD message WINDSHEAR (red), and aural message WINDSHEAR, WINDSHEAR, WINDSHEAR
Level One Test - Normal Indications - Terrain test pattern shows on ND for 12 seconds These messages should show at some time during the level one self test: - EICAS Advisory - GND PROX SYS - EICAS Advisory - WINDSHEAR SYS - EICAS Advisory - TERR POS - EICAS Status - GND PROX SYS - EICAS Status - WINDSHEAR REAC - EICAS Status - TERR SYS - Amber ND alert message - TERR TEST - Amber ND alert message - TERR FAIL
- Master warning lights on, PFD message PULL UP (red), TERRAIN alert message (red) on NDs, and aural message TERRAIN, TERRAIN, PULL UP. - Ground proximity light on and TERRAIN alert message (amber) on NDS - Terrain test pattern goes off. - Aural message SINKRATE - Aural message PULL UP
These visual and aural annunciations show for a normal level one test:
- Aural message DONT SINK
- ND system message TERR TEST shows in cyan
- Aural message DONT SINK
- Ground proximity warning light on and aural message GLIDESLOPE
- Aural message TOO LOW TERRAIN
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Level One Test - Normal Indications (cont) - Aural message TOO LOW GEAR - Aural message TOO LOW FLAPS - Aural message TOO LOW TERRAIN - Aural message GLIDESLOPE - Aural message BANK ANGLE, BANK ANGLE - Mode 6 altitude callouts - Aural message WINDSHEAR, WINDSHEAR, WINDSHEAR - Aural message TOO LOW TERRAIN - Aural message CAUTION TERRAIN, CAUTION TERRAIN - Aural message TERRAIN, TERRAIN, PULL UP
GPWS Mode Failures These aural messages annunciate for GPWS modes that do not function: - GLIDESCOPE INOP - GPWS INOP - BANK ANGLE INOP - CALLOUTS INOP - WINDSHEAR INOP - TERRAIN INOP.
Level One-Self Test - Non-Normal Indications The GPWS level one test fails for any of these conditions: - The terrain test pattern does not show - The TERR FAIL message on the ND stays on - You do not see and hear all annunciations.
Training Information Point Some GPWS modes have the same annunciations. If you do not see and hear all annunciations, the test fails.
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GPWS - LEVELS 2-5 - SELF-TEST General Description The ground proximity warning computer (GPWC) has six levels of self test: - 1 - GO/NO-GO operational test - 2 - Current faults - 3 - System configuration - 4 - Fault history - 5 - Alert/warning history - 6 - Discrete input test. Self test levels 2-6 access self test information not available through the control maintenance computer (CMC). Use a 600 ohm headphone to listen to the test information. Plug the headphone into the jack on the front panel of the GPWC. Use the self test button on the front panel of the GPWC to access levels 2-6. The self test button has these two modes:
Use the self test button for these functions: - Start self test level one - Go to the next item or flight leg within a test - Go to the next self test level - End the self test. When a test level ends, the aural message PRESS TO CONTINUE annunciates. Push the self test button to go to the next test level. If you do not push the self test button within three seconds, self test ends.
Level Two Self Test - Current Faults A level two test begins with the aural message CURRENT FAULTS. If there are no current faults, you hear the aural message NO FAULTS. If faults exist, the GPWC annunciates the faults one at a time. A short or long cancel ends the level two test.
- Short cancel - push the button for less than two seconds - Long cancel - push the button for more than two seconds.
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Level Three Self Test - System Configuration A level three test annunciates the GPWS configuration. A level three test begins with the aural message SYSTEM CONFIGURATION. A short cancel causes the test to go immediately to the next configuration item. A long cancel ends the level three test. A level three test provides this information: - GPWC part number - GPWC modification status - GPWC serial number - Application software version - Configuration software version - Terrain database version - Envelope modulation database version - Boot code version - Aircraft type - Audio menu - Altitude callout menu number - Selected options.
A level four test begins with the aural message FAULT HISTORY. If there are no faults in the flight history memory, you hear the aural message NO FAULTS. If there are faults in the flight history memory, you hear the most recent faults annunciate first. You hear the faults in this order: - FLIGHT X (X is the most recent flight leg number) - Internal faults for flight X - External faults for flight X - Go to next oldest flight leg and repeat. A short cancel causes the test to go immediately to the next flight leg. A long cancel ends self test level four.
Level Five Self Test - Warning History Level five self test annunciates GPWS alerts over the last ten flights.
Level Four Self Test - Fault History Level four self test annunciates the GPWS fault history over the last ten flights.
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Level Five Self Test - Warning History (cont) A level five test begins with the aural message WARNING HISTORY. If there are no alerts in the flight history memory, you hear the aural message NO WARNINGS. If there are alerts in the flight history memory, you hear the most recent alerts first. You hear the alerts in this order: - FLIGHT X (X is the most recent flight leg number) - GPWS alerts for flight X - Go to next oldest flight leg and repeat. A short cancel cause the test to go immediately to the next flight leg. A long cancel ends self test level four.
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GPWS - LEVEL 6 - SELF TEST General Description
Level Six Self Test - Discrete Input Test
The ground proximity warning computer (GPWC) has a level six discrete input test.
A level six test checks changes in discrete inputs.
This test accesses test information not available from the central maintenance computer (CMC). Use a 600 ohm headphone to listen to the test information. Plug the headphone into the jack on the front panel of the GPWC.
The test starts with the aural message DISCRETE TEST. If the state of a discrete input changes, you hear the new state of the discrete. You hear the aural message DISCRETE INPUT TEST - PRESS TO CANCEL every 60 seconds. Push a short or long cancel to end the self test.
Use the self test button on the front panel of the GPWC to access level six' The self test button has these two modes: - Short cancel - push the button for less than two seconds - Long cancel - push the button for more than two seconds. Use the self test button for these functions: - Start self test level one - Go to the next item or flight leg within a test - Go to the next self test level - End the self test When a test level ends, the aural message PRESS TO CONTINUE annunciates. Push the self test button to go to the next test level. If you do not push the self test button within three seconds, self test ends.
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GPWS - STATUS LEDS Purpose There are three status LEDs on the front panel of the ground proximity warning computer (GPWC). These LEDs turn on when there is power to the GPWC. These LEDs are: - External fault - yellow Computer OK - green Computer fail - red.
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NAVIGATION Ground Proximity Warning System
GPWS - SELF-TEST - 1
General
Display Control
The computer self-tests check the status of the computer and provide a front panel display of the present status of the GPWS or of GPWS faults that occurred during the last ten flight segments. No test results, either aural messages or visual indications, are annunciated in the flight deck during the GPWC self-tests.
The front panel display is controlled by the operator with the cancel and display hold features. Any section of the present status display sequence can be cancelled.
GPWC PRESENT STATUS Self-Test Momentarily press the STATUS/HISTORY switch on the GPWC front panel to the PRESENT STATUS position to start a present status test. The test results are shown on the front panel BITE display window. The all-segment, in-test and end-test sequences flash on, then off. The other messages go across the display from right to left. Present status failure messages are in the message tables that are shown. Only present failures are shown during the present status self-test. The SYSTEM OK message will show only if there are no GPWC or input failures.
Config: ALL Isue:
To cancel a display sequence, push the front panel STATUS/ HISTORY switch twice to either position within one second. When it is cancelled, the present status display will start with the next display sequence. For example, if the display is cancelled within the configuration message sequence, the remaining configuration data is skipped and the failure message sequence begins. In this way, the in-flight failure, present failures and software version displays can also be cancelled.
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NAVIGATION Ground Proximity Warning System
Boeing 747-400 Avionics
Display Control (cont) A display hold feature is also provided for the front panel display. Push the front panel STATUS/HISTORY switch to either position during any display to hold the display as it is at that time. The display will stay as long as the switch is pushed, up to 10 seconds. The display stays for 1.5 seconds when the switch is momentarily pushed to either position.
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NAVIGATION Ground Proximity Warning System
Boeing 747-400 Avionics
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NAVIGATION Ground Proximity Warning System
Boeing 747-400 Avionics
GPWS - SELF-TEST - 2
General GPWC BITE and system input monitor detected faults are logged in non-volatile memory as part of a flight history. Data about the last 10 flights is stored in this memory.
GPWC FLIGHT HISTORY Self-Test Momentarily press the STATUS/HISTORY switch on the GPWC front panel to the FLIGHT HISTORY position to start a flight-history test. The test results are shown on the front panel BITE display window. The flight-history failure messages go across the display from right to left. They are shown in the message tables. If the last 10 flights do not have faults, the fault-history display shows the PREVIOUS TEN FLIGHTS OK message. It then stops with the END TEST message. The display hold and cancel features are also available when performing a flight-history test. Any display message can be held on the display.
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NAVIGATION Ground Proximity Warning System
Boeing 747-400 Avionics
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NAVIGATION Ground Proximity Warning System
Boeing 747-400 Avionics
GPWS - FLIGHT DECK EFFECTS Purpose This graphic contains a summary of all maintenance related flight deck effects.
Flight Deck Effects Two status messages are available to show GPWS input and internal function faults: - GND PROX SYS - WINDWHEAR REAC. The GND PROX SYS message indicates a failure of the ground proximity function. The WINDSHEAR REAC message indicates a failure of the windshear function. Two EICAS advisory messages give the flight crew information about GPWS faults: - GND PROX SYS - WINDSHEAR SYS These advisory messages will show when the status messages show.
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NAVIGATION Ground Proximity Warning System
Boeing 747-400 Avionics
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NAVIGATION Ground Proximity Warning System
Boeing 747-400 Avionics
NOTES:
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NAVIGATION Standby Attitude Reference System
Boeing 747-400 Avionics
STANDBY ATTITUDE REFERENCE SYSTEM INTRODUCTION ....................................................................... 2 STANDBY ATTITUDE REFERENCE SYSTEM .............................. 4 STANDBY ATTITUDE REFERENCE SYSTEM - COMPONENT LOCATIONS ............................................................................. 6 STANDBY ATTITUDE REFERENCE SYSTEM - INTERFACE DIAGRAM ....................................................................................... 8 STANDBY ATTITUDE INDICATOR ................................................. 10 STANDBY ATTITUDE REFERENCE SYSTEM - ATTITUDE SCHEMATIC ....................................................................................... 12
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NAVIGATION Standby Attitude Reference System
Boeing 747-400 Avionics
STANDBY ATTITUDE REFERENCE SYSTEM - INTRODUCTION
The standby attitude reference system provides a backup source of attitude for the flight crew at all times during flight. The standby attitude reference system operates independently of the primary attitude system and main airplane power. 34.24.0701 -002
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NAVIGATION Standby Attitude Reference System
Boeing 747-400 Avionics
34.24.0201 -002
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NAVIGATION Standby Attitude Reference System
Boeing 747-400 Avionics
STANDBY ATTITUDE REFERENCE SYSTEM
System Description The standby attitude reference system is an alternate source of airplane pitch and roll attitude data. The system consists of a standby attitude indicator and one power circuit breaker.
Operation A vertical gyro connected to a sphere-type roll and pitch attitude display provides the flight crew with standby attitude. The display can indicate 107 degrees in climb, 63 degrees in dive and 360 degrees of roll. A cage knob mechanically accelerates the erection of the vertical gyro. A gyro fault flag shows for incorrect gyro speed or power.
Power The main battery bus provides 28v dc to the standby attitude indicator through a circuit breaker on the overhead CB panel. 34.24.0702 -002
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NAVIGATION Standby Attitude Reference System
Boeing 747-400 Avionics
34.24.0202 -002
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NAVIGATION Standby Attitude Reference System
Boeing 747-400 Avionics
STANDBY ATTITUDE REFERENCE SYSTEM - COMPONENT LOCATIONS
The standby attitude reference system components are: - Standby attitude indicator - Standby attitude reference system circuit breaker
34.24.0703 -002
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NAVIGATION Standby Attitude Reference System
Boeing 747-400 Avionics
34.24.0203 -002
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NAVIGATION Standby Attitude Reference System
Boeing 747-400 Avionics
STANDBY ATTITUDE REFERENCE SYSTEM - INTERFACE DIAGRAM
System Interface The standby attitude reference system receives 28v dc power from a standby instrument circuit breaker in the pilot's overhead circuit breaker panel.
34.24.0704 -002
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NAVIGATION Standby Attitude Reference System
Boeing 747-400 Avionics
34.24.0204 -002
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NAVIGATION Standby Attitude Reference System
Boeing 747-400 Avionics
STANDBY ATTITUDE INDICATOR
General
Characteristics
The standby attitude indicator has a gyro stabilized sphere that provides a horizon reference. The roll scale is on the top half of the case front. Bank indication is shown with marks at 0000nd 45The pitch scale appears on the face of the attitude sphere. Pitch angle is shown with marks every five degrees and numerals every ten degrees. The airplane symbol is attached to the case of the indicator and does not move.
The standby attitude indicator can display:
Control
- pitch attitude (+107imb, -63 dive) - roll attitude (+/-360 degrees) - gyro failure
34.24.0705 -002
The standby attitude indicator gyro can be erected in two ways: - Automatically: when the gyro erects at a rate of three degrees per minute after power is applied - Manually: when the gyro spins for thirty seconds, and then the cage knob is pulled out and held for a few seconds, the sphere will stabilize to a zero pitch and zero roll indication
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NAVIGATION Standby Attitude Reference System
Boeing 747-400 Avionics
34.24.0205 -002
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NAVIGATION Standby Attitude Reference System
Boeing 747-400 Avionics
STANDBY ATTITUDE REFERENCE SYSTEM - ATTITUDE SCHEMATIC
The standby attitude reference system uses a gyro-stabilized attitude sphere to show airplane attitude. The gyro will start the stabilization erection process at power-up. The gyro normally erects at a rate of three degrees per minute, or it is fast erected in a few seconds when the cage knob is pulled. The gyro rotor spins at a speed of 18,000 rpm and thus requires approximately nine minutes to run down prior to removal. A 28v dc to ac inverter provides 20v ac, three-phase 400 Hz power to the gyro motor. A gyro current-sensing circuit causes a gyro flag to come into view when the gyro power is detected as being incorrect. 34.24.0707 -002
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NAVIGATION Standby Attitude Reference System
Boeing 747-400 Avionics
34.24.0207 -002
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NAVIGATION Standby Attitude Reference System
Boeing 747-400 Avionics
NOTES:
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NAVIGATION Standby Attitude Reference System
Boeing 747-400 Avionics
34.24.0211 -002
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NAVIGATION Standby Attitude Reference System
Boeing 747-400 Avionics
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NAVIGATION Standby Magnetic Compass
Boeing 747-400 Avionics
STANDBY MAGNETIC COMPASS ................................................. 2
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NAVIGATION Standby Magnetic Compass
Boeing 747-400 Avionics
STANDBY MAGNETIC COMPASS
General
Power
The standby magnetic compass is a backup magnetic heading reference. It is installed forward of the overhead circuit breaker panel (P7). The compass is mounted to the airframe with non-ferrous material in an area of non-ferromagnetic components.
The compass card is illuminated by a 5v ac bulb. The bulb brightness is controlled by the panel lighting control on the pilots overhead panel (P5). A lamp access cover permits easy replacement of the light bulb.
Characteristics
Adjustment/Test
The standby magnetic compass is a sensitive instrument composed of a circular heading indicator card having two parallel and horizontal magnets. The card is floating in a liquid filled case amd is free to rotate and tilt. The liquid medium serves to dampen rapid movements and oscillations of the compass. The magnets align the compass with the earth's magnetic lines of flux. This rotates the compass card that is calibrated to show the airplane heading relative to the earth's magnetic field. The magnetic heading of the airplane is read from the card against a fixed lubber line.
The standby compass front panel has N-S and E-W compensator adjusters for alignment of the compass card. These comensators correct for magnetic deviations generated by airplane components and electrical currents in local wiring. A compass correction card is installed below the compass to record small errors that cannot be removed by the compass compensators. Note: Use only non-magnetic tools to adjust the standby magnetic compass.
34.22.0701A-001
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NAVIGATION Standby Magnetic Compass
Boeing 747-400 Avionics
Removal/Installation The standby magnetic compass is attached by four screws on the front panel. To remove the compass follow the maintenance manual procedures and adhere to these cautions: CAUTION: USE ONLY NONMAGNETIC TOOLS FOR REMOVAL AND INSTALLATION TO AVOID INSTRUMENT DAMAGE. CAUTION: DO NOT USE STEEL SCREWS TO ATTACH COMPASS TO PANEL AS THEY CAN CAUSE ERRONEOUS COMPASS INDICATIONS. Upon replacement of the standby compass, a compass swing is required. This is the only compass indicator on a 747-400 which requires a compass swing. Note: Ferromagnetic parts installed near the standby compass can cause compass heading errors. Make sure no ferromagnetic parts are near the captain's or first officer's window frames. If found, replace the parts with nonmagnetic, corrosion-resistant parts.
34.22.0701B-001
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NAVIGATION Standby Magnetic Compass
Boeing 747-400 Avionics
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NAVIGATION Standby Magnetic Compass
Boeing 747-400 Avionics
34.22.0201 -001
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NAVIGATION Standby Magnetic Compass
Boeing 747-400 Avionics
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NAVIGATION Inertial Reference System
Boeing 747-400 Avionics
INERTIAL REFERENCE SYSTEM ................................................. 4 INERTIAL REFERENCE SYSTEM - COMPONENT LOCATIONS -
IRS DISPLAYS - ND - EXPANDED MAP ........................................ 52 IRS DISPLAYS - ND - EXP MAP - NCD ......................................... 54
MAIN EQUIPMENT CENTER ................................................... 6 COMPONENT LOCATIONS - INERTIAL REFERENCE SYSTEM -
IRS DISPLAYS - ND - EXP MAP - INVALID .................................... 56 IRS DISPLAYS - ND - CTR MAP .................................................... 58
FLIGHT DECK .......................................................................... 8 INPUT POWER - LEFT AND RIGHT IRU ...................................... 10
IRS DISPLAYS - ND - PLAN ........................................................... 60 IRS DISPLAYS - ND - CTR VOR ................................................... 62
INPUT POWER - CENTER IRU..................................................... 12 IRS SIGNAL INPUTS (FMC & CMC) .............................................. 14
IRS DISPLAYS - ND - CTR VOR-NCD .......................................... 64 IRS DISPLAYS - ND - CTR VOR-INVALID ..................................... 66
IRS-ADC SOURCE SELECTION .................................................. 16 LEFT IRU BUS OUTPUTS ............................................................. 18
IRS EICAS MESSAGES ................................................................. 69 IRS GENERAL OPERATION ......................................................... 73
CENTER IRU BUS OUTPUTS ....................................................... 20 RIGHT IRU BUS OUTPUTS ........................................................... 22
IRS POWER UP ............................................................................ 76 IRS POSITION INITIALIZATION ...................................................... 78
IRS ON DC DISCRETE OUTPUTS ............................................... 24 IRU FAULT DISCRETE .................................................................. 26
INITIAL POSITION ENTRY MISCOMPARE .................................... 80 IRS-CALCULATED LATITUDE MISCOMPARE .............................. 82
INERTIAL REFERENCE UNIT ....................................................... 29 IRS MODE SELECTOR UNIT ........................................................ 32
IRS-CALCULATED LATITUDE MISCOMPARE - SECOND COMPARISON .......................................................................... 84
IRS SOURCE SELECT SWITCHES ............................................. 34 IRS SOURCE SELECT SWITCH - CAPTAIN ................................ 36
IRS ALIGNMENT INDICATIONS - NO PPOS ENTERED ............... 86 IRS ALIGNMENT INDICATIONS - EXCESSIVE MOTION ............... 88
FIRST OFFICER IRS SOURCE SELECT SWITCH ...................... 38 HEADING SELECT SWITCH ......................................................... 40
IRS RAPID REALIGN MODE ......................................................... 90 IRS HEADING INITIALIZATION - ATTITUDE MODE ....................... 92
IRU CONTROL .............................................................................. 42 IRS CONTROLS - CDU ................................................................. 44
FMC POSITION REFERENCE PAGE ........................................... 94 IRS MONITOR PAGE ..................................................................... 96
IRS DISPLAYS - PFD ..................................................................... 46 IRS DISPLAYS - PFD - NCD .......................................................... 48
IRU INTERNAL PROCESSING ...................................................... 98 IRS ON BATTERY WARNING ........................................................ 100
IRS DISPLAYS - PFD - INVALID ..................................................... 50
INERTIAL REFERENCE SYSTEM SELF-TEST ............................ 102
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Boeing 747-400 Avionics
INERTIAL REFERENCE SYSTEM INTERFACE TEST ................. 104 IRU INTERFACE TEST VALUES.................................................... 106 IRU INTERFACE TEST - PFD INDICATIONS ................................ 108 IRU INTERFACE TEST - ND INDICATIONS ................................... 110
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NAVIGATION Inertial Reference System
Boeing 747-400 Avionics
INERTIAL REFERENCE SYSTEM
Purpose The purpose of the inertial reference system (IRS) is to provide airplane orientation and movement data required for airplane control and navigation.
To make these calculations the IRU receives inputs from:
General Description
The MSU provides the means to select these IRU modes:
An inertial reference system consists of: - Inertial reference unit (IRU) - Mode selector unit (MSU) The IRU makes independent measurements of: - Airplane attitude change rates (3 axes) - Linear accelerations (3 axes)
- Air data computers (ADC) - Flight management computers (FMC)
- Off - Alignment - Navigate - Attitude In addition to navigational functions, the system performs testing and fault status reporting through the central maintenance computer system (CMCS). 34.21.0501 -001
The IRU calculates and provides: - Attitude - Heading (true and magnetic) - Velocities (horizontal and vertical) - Navigational information (position, ground speed, wind) - Accelerations
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Boeing 747-400 Avionics
34.21.0001 -001
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NAVIGATION Inertial Reference System
Boeing 747-400 Avionics
INERTIAL REFERENCE SYSTEM - COMPONENT LOCATIONS MAIN EQUIPMENT CENTER
The IRS components and interfacing components located in the main equipment center are: - Inertial reference units - ADC source select relays - IRU source select relays - IRS on battery relay - IRS on battery diodes - IRS ON BAT CB - IRS GND SVCE logic CB - Air/Ground relay
34.21.0502 -001
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Boeing 747-400 Avionics
34.21.0002 -001
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NAVIGATION Inertial Reference System
Boeing 747-400 Avionics
COMPONENT LOCATIONS - INERTIAL REFERENCE SYSTEM FLIGHT DECK
The IRS components and interfacing components located in the flight deck are as follows: - IRS mode selector unit - IRS source select switches - IDUs - Control and display units (CDUs) - IRS and ADC source select switches - Heading select switch - IRS DC power disconnect relay - IRS ON BAT indicator - AC and DC power circuit breakers - Center IRS disconnect relay and circuit breaker
34.21.0503 -001
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Boeing 747-400 Avionics
34.21.0003 -002
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NAVIGATION Inertial Reference System
Boeing 747-400 Avionics
INPUT POWER - LEFT AND RIGHT IRU
Each IRU receives 115 volts ac and 28 volts dc. Power is turned on inside the IRU in response to selection of any mode other than off on the MSU. The IRU normally uses ac power but will automatically switch to dc power when the ac power input fails.
34.21.0504 -001
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Boeing 747-400 Avionics
34.21.0004 -001
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NAVIGATION Inertial Reference System
Boeing 747-400 Avionics
INPUT POWER - CENTER IRU
The center IRU is supplied 115 volts ac and 28 volts dc. Power is turned on inside the IRU in response to selection of any mode other than off on the MSU. The IRU normally uses ac power but will automatically switch to dc power upon failure of the ac power input. The center IRU will operate on dc power from the APU hot battery bus for only five minutes if dc bus No. 3 also is lost. The dc power from the APU hot battery bus is removed by the IRS dc power disconnect relay to conserve battery power. The five-minute time delay is started when: - An operating mode is selected on the MSU (Align, Nav, Att). - DC bus No. 3 power is lost. The loss of the 28-volt dc bus No. 3 causes the center IRS disconnect relay to deenergize. 28 volts dc from the APU hot battery bus is supplied through the de-energized relay contacts to the 5-minute time delay in the IRS dc power disconnect relay.
Config: ALL Issue: 1
The following is a description of why loss of dc bus No. 3 results in the loss of dc power to the C-IRU if it had previously lost ac power and had transferred to the APU battery hot bus.
- If the C-IRU lost ac power due to loss of No. 1 ac bus, the APU hot battery bus charger also lost power. - The APU battery bus is normally powered from dc bus No. 3. If dc bus No. 3 fails, the APU battery bus automatically transfers to the APU hot battery bus for power. - With the added load of the APU battery bus, the APU battery is now supplying both busses. The C-IRU is removed to save the battery. 34.21.0505 -001
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NAVIGATION Inertial Reference System
Boeing 747-400 Avionics
34.21.0005 -001
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NAVIGATION Inertial Reference System
Boeing 747-400 Avionics
IRS SIGNAL INPUTS (FMC & CMC)
FMC Inputs In the align mode initial (present) position is entered through the FMC CDU. In the Att mode reference (magnetic) heading is entered through the FMC CDU.
CMC Inputs The test initiation discrete is supplied from the CMC when an IRU test is commanded. 34.21.0506 -001
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Boeing 747-400 Avionics
34.21.0006 -001
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NAVIGATION Inertial Reference System
Boeing 747-400 Avionics
IRS-ADC SOURCE SELECTION
The IRUs receive air data inputs from the captain's and the first officer's ADC source selected air data computers. The captain's or first officer's ADC source select switch and the first officer's IRS source select switch provide the discrete that selects the input port to be used. The captain's ADC switch controls the left IRU input and the first officer's ADC switch controls the right IRU input. The first officer's IRS source select switch controls the center IRU input. If the first officer's IRS source select switch is in L or C, the center IRU uses the ADC selected by the first officer. If it is in R, the center IRU uses the ADC selected by the captain.
34.21.0541 -001
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Boeing 747-400 Avionics
34.21.0041 -001
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NAVIGATION Inertial Reference System
Boeing 747-400 Avionics
LEFT IRU BUS OUTPUTS
The IRU transmits data on three ARINC 429 high-speed output busses. All output data is sent on all three busses.
- along track horizontal acceleration - cross track horizontal acceleration - vertical acceleration
The IRU digital outputs are: - latitude - longitude - N-S velocity - E-W velocity - ground speed - wind speed - wind direction - heading (magnetic and true) - drift angle - flight path angle - pitch attitude - pitch rate - roll attitude - roll rate - yaw rate - inertial altitude - inertial vertical speed - flight path acceleration - body longitudinal acceleration - body lateral acceleration - body normal acceleration
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34.21.0545 -001
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Boeing 747-400 Avionics
34.21.0045 -002
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Boeing 747-400 Avionics
CENTER IRU BUS OUTPUTS
The IRU transmits data on three ARINC 429 high-speed output busses. All output data is sent on all three busses. 34.21.0546 -001
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Boeing 747-400 Avionics
34.21.0046 -004
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Boeing 747-400 Avionics
RIGHT IRU BUS OUTPUTS
The IRU transmits data on three ARINC 429 high-speed output busses. All output data is sent on all three busses. 34.21.0547 -001
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Boeing 747-400 Avionics
34.21.0047 -004
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NAVIGATION Inertial Reference System
Boeing 747-400 Avionics
IRS ON DC DISCRETE OUTPUTS
Each IRU sends an analog discrete when it is operating on dc power. When any analog discrete is present, the relays in the P414 panel will energize if: - The airplane is on the ground - Any IRU is operating on dc only - No ground service bus power is available Energizing the P414 relays causes: - The ground crew call horn in the nose wheel well to sound. - The IRS ON BAT lamp, on the P461 panel in the flight deck, to come on. 34.21.0508 -001
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Boeing 747-400 Avionics
34.21.0008 -001
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NAVIGATION Inertial Reference System
Boeing 747-400 Avionics
IRU FAULT DISCRETE
Each IRU has an analog discrete output which is routed to each EIU to show a critical IRU fault condition. The discrete will cause the IRS (left, center or right) EICAS message to be displayed. A critical fault is one that may cause erroneous outputs of attitude, heading, angular rates or accelerations.
34.21.0509 -001
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Boeing 747-400 Avionics
34.21.0009 -001
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Boeing 747-400 Avionics
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NAVIGATION Inertial Reference System
Boeing 747-400 Avionics
INERTIAL REFERENCE UNIT
Purpose
Power
The purpose of the inertial reference unit is to provide:
The IRU operates from either 115 volts ac 400Hz, or 28 volts dc power. If 115 volts ac power is lost, the IRU automatically switches to 28 volts dc power (APU HOT BAT BUS).
- Attitude - Accelerations - Heading - Navigation data - Velocities
Control and Monitor Power is turned on internally in response to two mode select analog discretes.
Characteristics The IRU contains: - Ring-laser gyros to measure rotation rates
Program pins on the IRU are used for axis orientation for a particular airplane-type installation. There is an interface test switch on the IRU front panel which initiates an interface test of the IRU when pushed.
- Linear accelerometers to measure accelerations - A digital computer and other electronics used for signal processing and interfacing with other systems
Indications There is a fault ball on the IRU front panel to show the status of the unit. 34.21.0510A-001
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Indications (cont) If the fault has cleared, cycling the IRU power off and then back to on will clear the fault ball indication.
Installation and Removal Special consideration should be given for removal and installation of the IRU. The IRU rack mount and guide pin is accurately aligned, and must not be subjected to excessive pressures or impacts.
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IRS MODE SELECTOR UNIT
Purpose The purpose of the IRS mode selector unit (MSU) is to allow selection of the IRU modes of operation.
Operation The MSU contains one mode select switch for controlling each IRU. The switch sends discretes to the respective IRU for mode selection. The NAV position is detented to help ensure that the operator does not unintentionally switch out of the NAV position. 34.21.0511 -001
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IRS SOURCE SELECT SWITCHES
The captain's IRS source select switch determines which IRU will provide IRS display information for the left primary flight display (PFD) and navigation display (ND). The first officer's IRS source select switch determines which IRU will provide IRS display information for the right PFD and ND and selects the ADC input port for the center IRU. These switches also control which IRU output bus goes to the brake system and to the MAWEA card file for the stall warningcomputer. 34.21.0513 -001
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34.21.0013 -001
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IRS SOURCE SELECT SWITCH - CAPTAIN
EIU IRU Input Select Discretes One set of contacts on the IRS source select switch provides a ground on one of three analog discrete inputs to all three EIUs. These discretes select which IRU data bus provides EIU inputs.
Brake System IRU Input Select Discretes Another set of contacts of the switch provides a ground to one of two source select relays. With the switch in the center position, the relays switch the left brake system channel input from left IRU to the center IRU. With the switch in the right position, the relays switch the left brake system channel input to the right IRU.
Weather Radar IRU Input Select Discretes Another set of contacts of the switch provides a ground to the weather radar (WXR) transceiver for selection of the offside (center) IRU input.
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FIRST OFFICER IRS SOURCE SELECT SWITCH
EIU IRU Input Select Discretes
Weather Radar IRU Input Select Discrete
One set of contacts on the IRS source select switch provides a ground on one of three analog discrete inputs to all three EIUs. These discretes select which IRU data bus provides EIU inputs.
Another set of contacts of the switch provides a ground to the weather radar (WXR) transceiver for selection of the offside (center) IRU input. 34.21.0540 -002
Brake System IRU Input Select Discretes Another set of contacts of the switch provides a ground to one of two source select relays in the center or left positions. With the switch in the center position, the relays switch the right brake system channel input from right IRU to the center IRU. With the switch in the left position, the relays switch the right brake system channel input to the left IRU.
ADC Center IRU Input Select Discrete Another set of contacts of the switch provides a ground to the center IRU for selection of the input port of the captain's ADC.
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34.21.0040 -002
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HEADING SELECT SWITCH
The position of the heading select switch determines whether true or magnetic heading is used by the: - Flight deck instruments - The flight management computers - Flight control computers
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IRU CONTROL
The IRS mode selector unit (MSU) controls the mode of each IRU operation by grounding or opening contacts on the associated mode select switch. The IRU can be commanded to off, alignment, navigation, or attitude modes by the selection of OFF, ALIGN, NAV, or ATT respectively. Program pin connections indicate to the IRU computer the physical mounting orientation of the IRU. This is for the computer to correctly use the acceleration signals from the accelerometers and the angular rate signals from the gyros. The FMCs provide the initial position latitude and longitude (entered by the operator) for use in alignment and navigation. The FMCs also provide operator-entered heading for use in the attitude mode. Left FMC data is used unless its data becomes invalid and then right FMC data is used. The CMC can initiate an individual IRU test by grounding the remote test input. 34.21.0538 -001
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IRS CONTROLS - CDU
Entries Dependent on the mode selected, the CDU is used to enter either the airplane's present position or reference heading.
Messages The CDU scratch pad is used to show IRS related messages that indicate operator action requirements. 34.21.0512 -001
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IRS DISPLAYS - PFD
The primary flight display shows this IRS data: - Pitch attitude - Roll attitude - Magnetic or true heading - Vertical speed - Drift angle 34.21.0516 -001
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IRS DISPLAYS - PFD - NCD
When IRS information is NCD, these changes occur: - Roll pointer removed - Pitch scale removed - Vertical speed scale, pointer and readout removed - Sky and ground shading removed - Horizon line removed - Boundary removed - Heading tape numerics removed - Heading readout, dashes - Track pointer removed
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IRS DISPLAYS - PFD - INVALID
When IRS information is invalid, these changes occur: - Roll pointer removed - Pitch scale removed - Vertical speed scale, pointer and readout removed - Sky and ground shading removed - Horizon line removed - Boundary removed - ATT flag displayed - Heading tape numerics removed - Heading tape removed - HDG flag displayed - Pointer and readout removed - VERT flag displayed 34.21.0518 -001
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34.21.0018 -004
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IRS DISPLAYS - ND - EXPANDED MAP
In the expanded map mode, the IRS data shown on the ND is: - Drift angle - Groundspeed - Wind direction, speed and angle - IRU positions The IRU position indicators show the left, center and right IRU positions. They are shown when the position push button on the EFIS control panel is pushed. The values for track, groundspeed and wind are normally supplied by the FMCs. If the FMCs fail, these values come from the selected IRU.
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IRS DISPLAYS - ND - EXP MAP - NCD
With the EXP map mode shown on the ND and IRS information is NCD, these changes occur: - Heading readout shown as dashes - Heading tape numerics removed - Groundspeed numerics blanked - Wind direction and magnitude readout shown as dashes - Wind direction pointer removed - ADF pointers removed - Selected heading bug and vector removed - Track pointer removed - Map data removed - Map flag displayed NCD IRS data displays in the center map mode are the same as these described above. 34.21.0521 -001
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IRS DISPLAYS - ND - EXP MAP - INVALID
With the EXP map mode shown on the ND and IRS information is invalid, these changes occur: - HDG flag displayed - Heading tape removed - Heading tape numerics removed - Groundspeed removed - Wind direction and magnitude removed - ADF pointers removed - Track pointer removed - Selected heading pointer and vector removed - Map data removed - Map flag displayed Invalid IRS displays in the center map mode are the same as those above. 34.21.0522 -001
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34.21.0022 -001
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IRS DISPLAYS - ND - CTR MAP
In the center map mode, the IRS information shown on the ND is: - Magnetic or true heading - Heading (MAG/TRU) - Ground speed - Wind direction, speed and angle - IRU positions The values for track, ground speed and wind are normally supplied by the FMCs. If the FMCs fail, these values are supplied by the selected IRU. The IRU position indicators show the left, center and right IRU positions. They are displayed when the position push button on the EFIS control panel is pushed.
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IRS DISPLAYS - ND - PLAN
In the plan mode the IRS information shown on the ND is: - Magnetic or true heading - Heading (MAG/TRU) - Ground speed - Wind data The values for track, wind data and ground speed are normally supplied by the FMCs. If the FMCs fail, these values are supplied by the selected IRU. NCD and invalid IRS data displays in the plan mode are the same as those in the expanded map mode. 34.21.0523 -001
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34.21.0023 -001
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IRS DISPLAYS - ND - CTR VOR
In the CTR VOR mode the IRS information shown on the ND is: - Magnetic or true heading - Drift angle - Ground speed - Wind direction, speed and angle The values for track, ground speed and wind are normally supplied by the FMCs. If the FMCs fail, these values are supplied by the selected IRU. The IRS information shown for the expanded and full approach modes and the expanded VOR mode is the same as the display for the center VOR mode.
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34.21.0024 -001
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IRS DISPLAYS - ND - CTR VOR-NCD
With the CTR VOR mode shown on the ND and IRS data NCD, these changes occur:
- Wind direction and magnitude readout shown as dashes - Wind angle pointer is removed. NOTE: Wind speed data will be treated as NCD when TAS is less than or equal to 101 knots. - Ground speed numbers go blank - Heading tape numbers are removed - ADF pointer is removed - Selected heading bug is removed - To/from removed - CRS pointer and tail are removed - Deviation bar is changed to vertical with deviation kept NCD IRS displays in the expanded VOR and approach modes are the same as those described above. 34.21.0525 -001
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34.21.0025 -001
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IRS DISPLAYS - ND - CTR VOR-INVALID
When the CTR VOR mode is shown on the ND and IRS data is invalid, these changes occur: - Wind speed pointer and numbers are removed - Ground speed numbers and GS are removed - Heading tape and numbers are removed - ADF/VOR pointers are removed - Selected heading bug is removed - Drift angle pointer is removed - To/From is removed - CRS pointer and tail are removed - Dev bar is changed to vertical with deviation kept - Heading numbers are replaced with HDG flag - Heading annunciations are removed - Track line and drift pointer are removed Invalid IRS displays in the expanded VOR mode and approach mode are almost the same as those described above.
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34.21.0026 -001
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IRS EICAS MESSAGES
WARNING (LEVEL A) - None
CAUTION (LEVEL B)
Memo (LEVEL D) - IRS ALIGN MODE (L,C,R): shows that the IRU is in the alignment mode. 34.21.0527A-001
- >ATTITUDE: shows that the pitch or roll data received by the captain's and first officer's PFDs differ by 3 degrees or more.
Advisory (LEVEL C) - >IRS AC (LEFT, CENTER, RIGHT: shows that the IRU is on dc power. - >IRS DC (LEFT, CENTER, RIGHT): shows that the dc supply to the indicated IRU has failed. - IRS MOTION: shows that excessive airplane motion has been detected while at least one IRU in the alignment mode. - IRS (LEFT, CENTER, RIGHT): shows that the IRU has failed. - >SOURCE SEL IRS: shows that the captain's and first officer's PFDs and NDs are receiving IRS data from the same IRUs.
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STATUS (LEVEL S) - IRS AC (LEFT, CENTER, RIGHT): (same as advisory message) - IRS DC (LEFT, CENTER, RIGHT): (same as advisory message) - IRS (LEFT, CENTER, RIGHT): (same as advisory message) 34.21.0527B-001
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34.21.0027 -001
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IRS GENERAL OPERATION
Introduction
Off Mode
In normal operation, the IRS measures both the rate of rotation about the three axes of the airplane and the acceleration of the airplane along these three axes. From these measurements the IRS computes:
When the mode select switch is moved to the OFF position, ac and dc power are disconnected inside the IRU. In this condition, the on-off logic circuits are still powered.
- Airplane attitudes relative to local level - Headings relative to true north - Velocities - Present position
Alignment Mode When the mode select switch is moved from the OFF to the ALIGN or NAV position, the IRU is placed in the alignment mode. During alignment the IRU:
These computations require initial data which include the airplane's: - Relationship to local vertical - Relationship to true north - Present position - Present altitude These measurements and computations occur in four possible modes.
- Determines local vertical orientation - Determines true heading orientation - Initializes attitudes, velocities, altitude (based on ADC inputs) - Initializes present position (based on FMC inputs) When the alignment is completed and the mode select switch is in the NAV position, the IRU will automatically enter the navigation mode. If the mode select switch is in the ALIGN position, the IRU will stay in the alignment mode until NAV is selected on the MSU.
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Navigation Mode
Attitude Mode
In the navigation mode, the IRS measures rotation rates and accelerations to compute:
The attitude mode is used when the normal navigation mode of the IRU has failed.
- Attitudes - Velocities - Headings - Altitudes - Present position The IRU uses air data inputs to compute: - Ground speed - Inertial altitude - Vertical velocity - Wind speed - Wind direction
When the mode select switch is moved to the ATT position, the IRS will provide: - Attitude - Attitude rates - Heading - Acceleration - Vertical velocity In this mode the IRU does not provide position or ground speed data.
True/Magnetic Heading In the navigation mode the IRU provides: - Attitude and attitude rates - Accelerations - True and magnetic headings - Velocity vectors - Vertical velocity - Wind speed and direction - Latitude and longitude - Ground speed - Inertial altitude
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In the ALIGN, NAV and ATT modes, the IRU determines true heading. To calculate magnetic heading, inertial position is entered into a variation look-up table. Variation is applied to true heading to get magnetic heading. Both true and magnetic heading are output by each IRU. 34.21.0528B-001
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34.21.0028 -001
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IRS POWER UP
The IRUs are powered by moving the MSU mode select switch from OFF to NAV or ALIGN. When the switch is moved directly to NAV, the IRU will automatically enter the navigate mode at the end of the alignment period. In 12 seconds, the IRS EICAS memo messages IRS ALIGN MODE L; IRS ALIGN MODE C or IRS ALIGN MODE R, appear on the main EICAS display to show that the IRU is in the alignment mode. Also in 12 seconds, the POSITION control display unit (CDU) SET IRS message and corresponding box prompts appear on the POS INIT (position initialization) page. This tells the operator that a present position entry is required for the IRUs to complete alignment. 34.21.0529 -001
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34.21.0029 -001
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IRS POSITION INITIALIZATION
The airplane must be on the ground and stationary to enter the present position. Initial present position is entered from the left or right CDU in one of these ways: - Latitude/longitude is entered into the scratch pad using the keyboard, then using the line select keys into the SET IRS POS line. - Latitude/longitude is transferred from the LAST POS line to the SET IRS POS line, using the line select keys. - REF AIRPORT or REF AIRPORT and GATE is entered using the keyboard and the latitude/longitude is transferred to the SET IRS POS line using the line select keys.
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INITIAL POSITION ENTRY MISCOMPARE
When present position is first entered, it is compared with the last present position value stored in the IRUs. If the entered positions are not within 1 degree of the stored positions in either latitude or longitude the message (MSG) light on the CDU will come on and the ENTER IRS POSITION will appear in the CDU scratch pad. Verify the position entered and make any necessary corrections. If this corrected position is within 1 degree of the IRUs last known position, the IRUs will accept it and the ENTER IRS POSITION message will disappear. If the same position entry is made again, the IRUs will continue the alignment, and the ENTER IRS POSITION message will disappear. NOTE: This comparison will not be made during the first initialization following shop servicing of an IRU. 34.21.0531 -001
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34.21.0031 -001
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IRS-CALCULATED LATITUDE MISCOMPARE By the end of the 10-minute alignment period, the IRUs will have calculated their own latitude and will compare it to the operator-entered latitude. When these values differ by a certain amount (varies with latitude), the CDU message ENTER IRS POSITION is displayed. The present position must be re-entered. If the position passes the IRU comparison, the IRU will transition to the navigation mode. The CDU message ENTER IRS POSITION and the EICAS memo messages will disappear. 34.21.0534 -001
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34.21.0034 -001
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IRS-CALCULATED LATITUDE MISCOMPARE - SECOND COMPARISON
When the latitude comparison still fails following two consecutive correct latitude entries, the IRU will report a failure and will not enter the navigation mode. This is indicated by the EICAS advisory message on the main EICAS display. The IRU must be switched off for 30 seconds until the EICAS memo message disappears. The mode selector switch should then be placed to NAV. 34.21.0535 -001
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IRS ALIGNMENT INDICATIONS - NO PPOS ENTERED
When the 10-minute alignment period has elapsed and an initial present position (PPOS) has not been entered: - The message ENTER IRS POSITION is displayed on the CDU. - The MSG (message) light comes on, on the CDU. When a valid present position is entered, the condition will be corrected. 34.21.0533 -001
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34.21.0033 -001
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IRS ALIGNMENT INDICATIONS - EXCESSIVE MOTION
When the airplane experiences excessive motion, while the IRUs are in the alignment mode, this will occur: - IRU alignment stops, and memo message IRS ALIGN MODE L (C or R) no longer is displayed. - The EICAS advisory message IRS MOTION will be shown on the main EICAS display until 30 seconds after the motion stops. - The IRUs will automatically restart an 8-minute alignment period when the motion stops. IRS ALIGN MODE L (C or R) is displayed. 34.21.0532 -001
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34.21.0032 -001
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IRS RAPID REALIGN MODE Position Miscompare The IRS rapid realign mode provides the capability for the operator to quickly re-initialize the IRS without going through the 10-minute alignment process.
NAV To ALIGN To NAV With the IRU in the navigation mode, and with the airplane stationary, the operator may select ALIGN and immediately re-select NAV on the MSU. This puts the IRU in the rapid realign mode and IRS ALIGN mode (L, C, R) is shown on the main EICAS display. In this mode, all velocities, and pitch and roll errors are corrected. Present position can be updated within thirty seconds. Approximately thirty seconds after rapid realign mode entry, the IRU will return to the navigation mode.
In the case of either NAV to ALIGN to NAV or NAV to ALIGN, a newly entered position must be within 1/2 degree latitude and 1 degree longitude of the internal IRU position. If the comparison fails, the scratch pad message, ENTER IRS POSITION, is displayed. If the comparison fails after a position re-entry, the scratch pad message, CYCLE IRS OFF-NAV, appears. The IRU is probably defective but alignment can be started over to verify the condition.
34.21.0537 -001
NAV To ALIGN When the mode selector switch is moved from NAV to ALIGN position, velocities, accelerations and rates are set to zero. Present position can be updated at any time. The IRU corrects heading and pitch and roll errors as long as the mode selector switch is in the ALIGN position.
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34.21.0037 -001
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IRS HEADING INITIALIZATION - ATTITUDE MODE
The attitude mode is a degraded mode of operation. If the navigation capability of an IRU fails or a temporary total power failure occurs it may be possible to operate in the attitude mode and obtain pitch, roll and heading data from the IRU. If there has been a complete loss of power to an IRU in flight, the IRU would need to be re-aligned and re-initialized. In this example, the right IRU mode selector switch is placed in the ATT position. The IRS EICAS memo message IRS ALIGN MODE R appears on the main EICAS display. This message will remain until the attitude mode is fully operational which normally takes 20-30 seconds. In flight, the airplane must maintain a constant velocity and level attitude for the attitude mode to become operational. When the right IRU mode select switch is placed in the ATT position, SET IRS HDG and dash prompts appear on the CDU. This allows the operator to initialize the IRS heading. Enter the desired reference heading through the CDU keyboard. When ATT mode is selected, the IRU is latched into the attitude mode (regardless of MSU switch position) until power is removed from the IRU by selecting the OFF position. 34.21.0536 -001
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FMC POSITION REFERENCE PAGE
General The FMC position reference page provides latitude, longitude and ground speed for each IRU. Note that when on the ground and with an IRU in NAV, ground speed is IRU drift rate.
Page Access Access the POS REF page by: - Use line select POS on the index page. - Use line select POS INIT from IDENT page. - Select INIT/REF mode key when on the ground and the IRS position has not been initialized. - Use line select POS INIT from the TAKEOFF REF page. - Access the POS REF page by NEXT PAGE mode key from the POS INIT page 1/2.POS REF Page - (2L through 4L): These lines show IRU latitude, longitude and ground speed. 34.21.0563 -001
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IRS MONITOR PAGE
General The IRS MONITOR page shows the average rate of drift of each IRU from the FMC, during the flight.
Page Access The IRS MONITOR PAGE can be accessed only on the ground. It is accessed from the INIT/REF INDEX page via the MAINT line select key, then the IRS MONITOR line select key.
IRS MONITOR Page The total drift (in miles) of each IRU from the FMC position is obtained by multiplying the drift rate (from the page) times the flight duration (in hours).
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IRU INTERNAL PROCESSING BITE Inertial Sensor Assembly The inertial sensor assembly contains the accelerometers and gyros (rotation sensors). The accelerometers measure the acceleration along the airplane axes. The gyros measure the rates of rotation about these axes. The data are sent to the inertial computer for use in alignment and navigation computations.
The BITE module interprets the status received from the two computers and provides status feedback to the inertial computer. The BITE module also provides fault ball drive and the FAULT discrete to the EIUs for EICAS fault messages.
IRS On DC Output Inertial Computer
When the IRS has switched to operation on dc power, a discrete is sent to initiate the appropriate annunciations.
The inertial computer performs the processing required for built-in-test and monitor, alignment, navigation and status reporting. Bus Outputs Input/Output Computer The input/output computer receives inputs, formats them and passes them on to the inertial computer and output buffer. It also receives inertial computer outputs that it formats and outputs to BITE logic, to decoder logic, and to the bus output buffer and drivers.
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There are three ARINC 429 output busses which transmit identical data to user systems.
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IRS ON BATTERY WARNING
The IRU normally operates on ac power. If ac power is lost, the IRU will automatically switch to dc power from the APU hot battery bus. If the aircraft is on the ground, a discrete causes the IRS on battery relay to energize in 10 seconds. Normally, the IRS ground service relay is energized by the ground service ac bus. This bus powers the APU battery charger, so dc power used by an IRU is from the charger. If the ground service bus is lost, the IRS ground service relay opens. If this happens when the IRS on battery relay is closed, the ground crew call horn sounds and the IRS ON BATTERY light comes on.
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INERTIAL REFERENCE SYSTEM SELF-TEST
Ground Test
Output Test Values
The CMC ground tests menu lists the systems for which ground tests are available. This menu allows a ground interface test of the left, center, or right IRU. To do an IRU interface test, GROUND TESTS is selected on the CMC MENU page 1. The GROUND TESTS page containing the required IRU test is then selected (by ATA chapter number). The IRU interface test is started by a push of the line select key adjacent to the IRU to be tested. The CMC holds the test discrete on for thirty seconds. Test completion is indicated by the word DONE adjacent to IRU-C.
During a part of the interface test, the IRU transmits test values on the output busses. Some of these values can be observed on the IDS as shown later. 34.21.0557 -001
IRU Front Panel Test An interface test can also be started by a push of the interface test button on the front of the IRU.
IRU Front Panel Indications BITE occurs at power up and throughout IRU normal operation. When a critical fault is detected by the BITE circuits the yellow fault ball is set. The black fault ball is set when no fault is detected.
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INERTIAL REFERENCE SYSTEM INTERFACE TEST
Push the line select key adjacent to an IRU to initiate the ground test. This causes the IRU in test and IN PROGRESS message to be shown and removal of the untested IRUs. ABORT with a prompt is also shown at LSK 6L.
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IRU INTERFACE TEST VALUES
The graphic shows the interface test output values from the IRU and the display locations. These outputs are transmitted during the first two seconds of the interface test and again after ten seconds. From two seconds after test initiation until ten seconds after test initiation, these test values are transmitted as failure data. Test values are also shown after ten seconds. The IRS source select switches are used to show the outputs from the IRU under test. Ground speed, drift angle and track angle show test value if the IRU under test is the only IRU aligned. If this is not the case, the values shown are from the FMC which uses any valid IRU data. 34.21.0559 -001
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IRU INTERFACE TEST - PFD INDICATIONS
The IRU test outputs on the PFD are shown on the graphic. Track and drift angle show test value if the IRU under test is the only IRU aligned. If this is not the case, the track shows 15° and the flight path vector shows 0° drift angle. 34.21.0560 -001
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IRU INTERFACE TEST - ND INDICATIONS
The IRU test outputs on the ND are shown on the graphic. Ground speed and track angle show test value if the IRU under test is the only IRU aligned. If this is not the case, the ground speed shows 0 and the track shows 15°.
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GLOBAL POSITIONING SYSTEM -INTRODUCTION .................... 2 GLOBAL POSITIONING SYSTEM .................................................. 4
GPS - POSITION REFERENCE - LAT/LON .................................. 24 GPS - POSITION REFERENCE - BRG/DIST ................................ 26
GPS - COMPONENT LOCATIONS - FLIGHT DECK ..................... 6 GPS - COMPONENT LOCATIONS - FUSELAGE ......................... 8
GPS - SATELLITE OPERATION .................................................... 29 GPS - GPS/MMR CALCULATIONS ................................................ 33
GPS - COMPONENT LOCATIONS - MEC..................................... 10 GPS - INTERFACE DIAGRAM ....................................................... 12
GPS - OPERATING MODES ......................................................... 37 GPS - GPS INTERNAL PROCESSING ......................................... 40
GPS - GPS MULTI MODE RECEIVER ........................................... 14 GPS - GPS ANTENNA ................................................................... 16
GPS - SYSTEM TEST.................................................................... 44 GPS - MMR BITE ........................................................................... 46
GPS - NAVIGATION DISPLAY ........................................................ 18 GPS - POSITION INITIALIZATION .................................................. 20
GPS - FLIGHT DECK EFFECTS ................................................... 48 GPS - GLOSSARY OF TERMS ..................................................... 50
GPS - POSITION REFERENCE - GPS ENABLE .......................... 22
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GLOBAL POSITIONING SYSTEM -INTRODUCTION The global positioning system (GPS) is a satellite-based radio navigation system which uses navigation satellites to calculate accurate airplane position and time. This data goes to airplane systems and to displays for the flight crew. The GPS system became fully operational in the early 1990's. The GPS satellite system is designed to operate using 24 satellites; 21 primary and 3 spares. The actual number of satellites that are operational can vary. This is due to satellite failures and satellite replacement schedule. Although designed as a military system, civil use of the system is an integral part of navigation systems.
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GLOBAL POSITIONING SYSTEM - INTRODUCTION
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GLOBAL POSITIONING SYSTEM The global positioning system (GPS) calculates: -Latitude -Longitude -Altitude -Accurate time There are two GPS antennas and two GPS multi mode receivers (GPS/MMR). The antennas connect to their respective GPS/MMR. The GPS/MMRs calculate the airplane position and update the GPS clock. This data goes to the flight management computer system (FMCS) and to the airplane condition monitoring system (ACMS) data management unit (DMU).
The inertial reference units (IRUs) send latitude and longitude to the GPS/MMRs for initialization. This allows the first satellite position fix to take place within 75 seconds from power-up. Short periods of adverse satellite coverage can occur. When this happens, the GPS/ MMRs use IRU data to aid in continued calculation of airplane position when not enough satellites are in view., This IRU input also lets the GPS/MMRs reacquire the satellites needed to re-enter the navigate mode quickly.
The navigation function in the FMCS uses GPS and other navigation sensors to calculate the airplane position. GPS position data is observed on the control and display unit (CDU). The FMCS uses universal coordinated time (UTC) from the GPS as a reference for calculations. If the GPS/MMRs are not initialized with latitude and longitude, the first satellite position fix can take up to 10 minutes.
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GPS - COMPONENT LOCATIONS - FLIGHT DECK The GPS interfacing components located in the flight deck are the: -Left inboard IDU -Left outboard IDU -Lower IDU -Upper IDU -Right inboard -IDU Right outboard IDU -Right control display unit (CDU) -Left CDU -Center CDU -Multi Mode Receiver (MMR) circuit breakers
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GPS - COMPONENT LOCATIONS - FUSELAGE The two GPS antennas are installed on the top of the fuselage.
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GPS - COMPONENT LOCATIONS - MEC The left and right GPS Multi Mode Receivers (GPS/MMR) are installed in the Main Equipment Center (MEC) on the E1-2 and E1-4 equipment racks.
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GPS - INTERFACE DIAGRAM Power and Antenna Interface Each GPS multi mode receiver (GPS/MMR) has its own circuit breaker. The 115V AC STBY BUS supplies power to the left GPS/ MMR and the 115V AC BUS 2 supplies power to the right GPS/ MMRs. Each GPS/MMR receives radio frequency (RF) energy from its own GPS antenna.
-True and magnetic headingTrack -Inertial altitude -Inertial vertical speed
GPS Data Output Bus Each GPS/MMR sends GPS data to the FMCs and to the DMU. The GPS data includes:
IRU Data Bus The GPS/MMR get inertial reference data from the IRUs. The left GPS/MMR receives data from either the left IRU or the center IRU. The right GPS/MMR receives data from the right IRU or the center IRU. Normally the onside input bus is used. If the onside bus is invalid the offside bus is used. The GPS/MMRs use this data for system initialization and to help operation during periods of low satellite coverage.
-GPS Position -GPS time -Horizontal figure of merit (HFOM) -Horizontal integrity limit (HIL) -Satellite coverage fall (SAT FAIL) -Fault data GPS fault data, for central maintenance computer (CMC) messages, are sent through the FMCs.
The IRU sends: -Latitude -Longitude -True air speed -Ground speed
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GPS - GPS MULTI MODE RECEIVER Purpose The multi mode receiver (MMR) is an LRU which combines the functions of an ILS receiver, a microwave landing system receiver, and a GPS receiver in a single unit. The GPS section of the MMR activates when installed in the left or right position. The GPS/MMR receives navigation satellite signals and calculates GPS data.
Physical Description The GPS/MMR dimensions are 9.5 inches (24 cm) long, 8.5 inches (22 cm) wide, and 2.5 inches (6 cm) tall. The GPS/MMR is an L-band receiver and a computer in one unit. The GPS/MMR uses 115v ac for operation, and has passive cooling. The GPS/MMRs are located in the main equipment center.
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GPS - GPS ANTENNA The GPS antennas receive L-band frequency signals from navigation satellites and send them to the GPS/MMRs. The GPS antennas use built in preamplifiers to reduce RF signal loss. The antenna preamplifiers use 12v dc from the power supply in the MMR.
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HOLE FOR MOUNTING SCREW (4)
TOP VIEW
CONNECTOR
BOTTOM VIEW
GPS - GPS ANTENNA
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GPS - NAVIGATION DISPLAY Position Display
Radio Position Update Display
The IRU, VOR/DME and GPS position indications show when the position (POS) display map data selector button, on the EFIS control panel is pushed.
The FMC can use GPS alone or along with other navigation sensors. Radio position update mode shows on the navigation display in the MAP modes.
The GPS Position indicators (GPS symbols) show either the left, right, or left and right GPS positions. When the distance between GPS Positions is small enough that one symbolls circle touches or overlaps the other symbol’s circle, only one symbol shows.
The radio position update mode display can show one of these radio radio position update modes:
The IRU Position indicators (asterisks) show the Left, center, and right IRU positions. VOR/DME positions show as a bearing and distance line from the airplane symbol to the NAVAID on the map.
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-LOC GPS (LOCALIZER GPS) -LOC DD (LOCALIZER DME DME) -LOC VD (LOCALIZER VOR DME) - LOC (LOCALIZER) - GPS (GLOBAL POSITIONING SYSTEM) - DD (DME DME) - VD (VOR DME)
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GPS - POSITION INITIALIZATION General The position initialization (POS INIT) page provides position initialization data to the inertial reference system (IRS) for alignment. To show the position initialization page, push the INIT REF key on the CDU.
GPS Position -(4R) GPS POS: This line shows the left GPSSU position if the GPSSU is reporting a valid position within a specific limit. If the left GPSSU exceeds this limit, data from the right GPSSU shows. This line is blank if neither GPSSU is valid.
The GPSSUs send GPS latitude, longitude, ground speed, and time to the FMC. This data shows on the position initialization pages in the FMC menu.
GPS Time -(4L) UTC (GPS or MAN): GPS time shows on this-line if the GPS time is valid from the left GPSSU. If the left GPSSU is not valid, time from the right GPSSU shows. If GPS time is not valid, time from the captain's clock (MAN) shows. If time from the captain's clock is not valid, time from the first officer's clock shows.
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GPS - POSITION REFERENCE - GPS ENABLE General The position reference (POS REF) page two, with GPS enabled, shows the current FMC position using the GPS to update that position. This page also provides the ability to cancel the GPS/radio update.
FMC Position -(1L) FMC POS (GPS L, GPS R, LOC GPS L, LOC GPS R, LOC DD, LOC VD, LOC, or RADIO): This line shows the current FMC computed airplane position and the update mode.
Purging of Updates -(5L) PURGE: Selection of this line results in the dynamic display of the IRS position in line 1L. CONFIRM then shows on line 5L. Selection of CONFIRM causes the FMC position to revert to the IRS position.
GPS Update Inhibits -(5R) GPS NAV: Selection of this line inhibits the use of GPS data for position updating, and causes ENABLE to show. Selection of ENABLE will cause GPS updating to resume.
Required and Actual Navigation Performance -(3L) RNP/ACTUAL: This line shows the required navigation Performance followed by the actual navigation performance (ANP). RNP and ANP are FMC functions.
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GPS - POSITION REFERENCE - LAT/LON On Position reference (POS REF) page three, the left GPSSU data shows in line 4 and the right GPSSU data shows in line 5. This data is latitude, longitude, and ground speed. -(6R) BRG/DIST: Selection of this line causes the positions on lines 1L through 5L and 2L on POS REF page 2, to show in a bearing distance format relative to the FMC position.
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GPS - POSITION REFERENCE - BRG/DIST On position reference (POS REF) page three, the left GPSSU data shows in line 4 and the right GPSSU data shown in line 5. This data is bearing and distance to the FMC position. -(6R) LAT/LON: Selection of this line causes the positions on lines 1L through 5L and 2L on POS REF page 2, to show in a latitude and longitude format.
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GPS - SATELLITE OPERATION GPS Segments
Control Segment
The GPS has three segments:
The control segment has control and monitor stations on earth that continuously monitor and track the satellites. The purpose of the control segment is to:
-Satellite -User -Control Satellite Segment The satellite segment is a group of satellites that orbit approximately 10,900 nautical miles above the earth. Each satellite completes an orbit once every 12 hours. A full group of operational satellites is now in orbit. There are 21 primary satellites and 3 spares.
-Monitor and correct satellite orbits and clocks. -Calculate and format a satellite navigation message. This message has up-to-date descriptions of the satellites’ future positions, and a collection of the latest data on all GPS satellites. -Update the satellite navigation message regularly. The control segment has one master control station and five monitor stations. Three of the monitor stations are also upload stations.
User Segment The user segment is the GPS sensor unit (GPSSU) on the airplane. It receives the satellite signals. The GPSSU uses the satellite data to calculate the airplane position.
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Control Seagment (cont) The master control station is in Colorado Springs, Colorado (USA). The master control station is the operational center of the GPS. The master control station controls all operations in the control segment. The master control station has an atomic clock. This clock is the reference for the GPS. The monitor stations track the satellites 24 hours a day. The master control station remotely controls the monitor stations through on-line connections. The monitor stations are in:
-Continuously measure the ranges to all visible satellites. The master control station uses this data to calculate and predict the satellite orbits. The master control station uses the upload stations to send: -Orbit correction commands to the satellites. The satellites use control rockets to correct their orbits. -The navigation message to the satellites.
-Ascension Island -Colorado Springs -Diego Garcia Island -Hawaii -Kwajalein Island
The upload stations are in Ascension Island, Diego Garcia Island, and Kwajalein Island.
The monitor stations receive the same information from the satellites that the GPSSUs receive. The monitor stations: -Record the accuracy of the satellite clocks -Collect and relay to the control station meteorological data, such as barometric pressure, temperature, and dew point. The master control station uses this data to calculate the satellites' tropospheric signal delay.
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SATELLITE SEGMENT
USER SEGMENT
CONTROL SEGMENT
GPS - THEORY OF OPERATION - 1
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GPS - GPS/MMR CALCULATIONS Values Calculated by the GPS/MMR These are the values that the GPS/MMR calculates: -Latitude -Longitude -Altitude -Universal coordinated time (UTC) -Date -North/south velocity -East/west velocity Accelerations -Track angle -Satellite position -Accuracy -GPS/MMR status.
The GPS/MMR measures the time it takes for a radio signal to go from a satellite to the airplane. Since the GPS/MMR knows the location of the satellite and that the radio signal travels at the speed of light, it can calculate the distance to the satellite. Since this is one way ranging, the GPS/MMR must know exactly at what time the satellite sent the radio signal. The GPS/MMR compares the satellite signal to a signal that the GPS/MMR generates at the same time as the satellite. The difference between the two signals, called delta t, is the time the signal took to get to the GPS/MMR. Each satellite has atomic clocks to keep accurate time to within 100 nanoseconds.' All the satellites have precisely the same time. The GPS/MMR in the airplane has an internal clock but it is not atomic and it is not as accurate. Thus, it is not possible for the GPS/MMR to have precisely the same time as the satellite.
Ranging The GPS/MMR use the principle of ranging to measure the distance between the GPSSU and the satellites. The GPS/MMR has in memory an almanac of the location of the satellites in their orbits at any time.
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Ranging (cont) The GPS/MMR assumes that its internal clock is off by some clock bias, called the delta t-BIAS. This delta t-BIAS is an unknown that the GPS/MMR must calculate. The delta t-BIAS represents the difference between the GPS/MMR time and the satellite time. The range calculations for each satellite include the delta t-BIAS. To calculate the airplane position, and the delta t-BIAS, the GPS/ MMR must range at least four satellites. The GPS/MMR measures the distances to all the satellites at the same time, and solves for the four unknowns, latitude, longitude, altitude, and delta t-BIAS with four range equations.
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RANGE 1 GPS TIME
RANGE 2
GPS TIME
RANGE 4 RANGE 3
RANGING ~T
~T
GPS - THEORY OF OPERATION - 2
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GPS - OPERATING MODES GPS Modes of Operation The GPS multi mode receiver (GPS/MMR) operates in these modes: -Self-test mode -Initialization mode -Acquisition mode -Navigation mode -Altitude aiding mode -Aided mode -Fault mode.
Self-Test Mode During the self-test mode, the GPS/MMR tests its circuits to verify proper operation. If the self-test passes, the GPS/MMR enters the initialization mode. If the self-test fails, the GPS/MMR enters the fault mode.
complete, the GPS/MMR enters the acquisition mode.
Acquisition Mode The GPS/MMR looks for and locks on to the satellite signals. The GPS/MMR must find at least 4 satellites before it starts to calculate GPS data. The GPS/MMR accepts position and altitude from the IRUs if available. The GPS/MMR uses the inertial data to calculate which satellites are in view, at the present airplane position. If the inertial data or clock data is not available, the GPS/MMR can still acquire satellite signals. However, the GPS/MMR takes longer to acquire the satellite signals because it has to look for all the satellites. When the GPS/MMR finds the satellites, it calculates which ones to track. Without a valid initialization, the time to the first fix is approximately 10 minutes. A valid initialization requires position and time.
Initialization Mode The GPS/MMR enters the initialization mode after power-up has occurred and the self-test passes. This mode lasts about 30 seconds while the signal processing sections are initialized with values of latitude, longitude, and altitude. During this mode there are no navigation or measurement outputs. Once the initialization is
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Navigation Modes The GPS/MMR enters the navigation mode after it acquires and locks on to at least 4 satellites. When the GPS/MMR is in the
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navigation mode it updates positions, velocities, accelerations, and time.
If the GPS/MMR cannot aquire four satellites in 30 seconds, the GPS/MMR goes back to the acquisition mode.
If the GPS/MMR is unable to track at least four or more satellites, the GPS/MMR enters the altitude-aided mode.
Fault Mode
Altitude-Aided Mode
The GPS/MMR enters the fault mode if a critical fault is detected. In this mode the normal ARINC 429 outputs are invalid.
With four satellites in view, the GPS/MMR stores the difference between the inertial altitude and the GPS altitude. With only three satellites in view it can estimate the GPS altitude.
GPS - Altitude-Aided Mode
In the altitude - aided mode, the GPS/MMR uses the inertial altitude and the length of the earth's radius as the fourth range.
In the altitude-aided mode, the GPS/MMR uses the inertial altitude and the length of the earth radius as the fourth pseudo range. This mode is used when the GPS/MMR is unable to track four or more satellites.
The GPS/MMR re-enters the navigation mode when four satellites are acquired.
To enter the altitude - aided mode, three conditions must be true: -The GPS/'MMR was in the navigation mode.
Aided Mode -There are 3 satellites available with good geometry for fixes The GPS/MMR enters the aided mode during short periods (less than 30 seconds) of bad satellite coverage. In the aided mode, the GPS/MMR receives altitude, track, and ground speed from the IRU.
-The GPS/MMR has previously stored the difference between inertial and GPS altitude.
The GPS/MMR uses the inertial data to go back quickly to the navigation mode, when there is good satellite coverage again.
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GPS - GPS INTERNAL PROCESSING Power
RF Section
The processor has 12 channels and can handle up to 12 satellites at the same time. Some of the channels are processing data from a set of tracked satellites and others are processing data to be used in searching for and aquiring new satellites.
The RF section receives the satellite signals from the GPS antenna. The signals are filtered and amplified. They are then sent to an analog to digital (A/D) converter.
The processor uses a twelve-state Kalman filter. The filter states are: three positions, three velocities, three accelerations, an altitude bias error, user clock phase error, and user clock frequency error.
The MMRs get 115v ac power from the airplane buses.
A/D Conversion The A/D converter changes the analog signal to digital data, which is used by the digital signal processor computer.
Micro Processor
Measurements obtained from the satellite signals are compared with estimates computed in a previous filter update. The resulting differences are used for updates. These updates occur in the navigation mode. At least four GPS satellites are tracked in the navigation mode. Inputs to the processor are navigation data from the ARINC 429 receivers and satellite data from the software data load. These inputs are used to determine satellite position and velocity.
The signal processor controls tracking, measures time from the satellite signals, determines signal validity, and decodes the satellite data.
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ARINC 429 Receivers
Continuous BITE Monitor
The IRU initiation data is used during the initialization mode, after power-up.
Fault monitoring of the GPS processor, satellite data, A/D conversion, and RF signal integrity is continuous. When a critical fault is detected the GPS fault mode begins. In this mode all ARINC 429 outputs are invalid.
IRU navigation data is used when less than 4 satellites are being tracked. This data is used in the aided mode.
NVM Navigation Calculations Navigation position calculations use the position updates from the Kalman filter, from each of the four satellites being tracked, to determine the user's location.
When a fault is detected, the GPS records the fault in non-volatile memory (NVM). This is used to aid shop maintenance. When the NVM is full, the recording of the present fault replaces the recording of the oldest fault.
GPS Clock The GPS Clock is updated by the navigation solutions. A clock bias is then calculated.
ARINC 42 Transmitters Satellite measurements and navigation data are used to update the GPS position, velocity, and clock. This information also goes to the flight management computer (FMC) and to the data management unit (DMU).
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RAM The receiver autonomous integrity monitor (RAIM) is used to detect and isolate errors in satellite measurements. Measurements from five satellites provide redundancy and an integrity check on the entire constellation being used. The RAIM algorithm sends an integrity figure of merit to the FMC. The figure of merit is called the horizontal integrity limit (HIL). The FMC determines if it can use the GPS data based on the HIL. If measurements from six satellites are available, the faulty satellite can be identified. That satellite is eliminated from the navigation calculations.
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GPS - SYSTEM TEST General The system test procedure uses one of the CDUs to make sure the global positioning system operation is satisfactory. The GPS system is initialized, with the airplane in a position where the GPS antennas have a clear view of the sky. The GPS position and time to first fix results are monitored.
Position Initialization Establish electrical power, turn on, and initialize the IRUs. Use the keyboard to enter the airplane present position.
Monitoring of Results Display the POS REF (Position Reference) page 3 of 3 and make sure the left GPS and right GPS latitudes and longitudes show. The TTFF (Time to First Fix) is approximately 5 to 6 minutes and the GPS positions will not show until this first fix occurs. The maximum TTFF should be less than 10 minutes.
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GPS - MMR BITE Front Panel Self-Test When you push the test switch, the MMR does a check of the internal operation and its interface with the GPS antenna. The test takes approximately 36 seconds. This is the test sequence that shows on the status LEDs during the test: -0 to 2 seconds, the LRU STATUS and the CONTROL FAIL LEDs are red -2 to 4 seconds, the LRU STATUS LED is green and the CONTROL FAIL LED is red -4 to 6 seconds, all LEDs go off -6 to 36 seconds, test status shows. NOTE:The ANT FAIL LED is not used at this time. The LRU STATUS LED shows red when there is an internal failure in the MMR. A green LED shows that the MMR is normal. The CONTROL FAIL LED shows red when an interface to the MMR has a failure.
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GPS - FLIGHT DECK EFFECTS General This is a summary of the GPS flight deck effects.
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GPS - GLOSSARY OF TERMS Appendix - A Acquisition - The act of acquiring. A GPS operating mode used to look for and find the satellites needed for position determination. The satellite signals are acquired and then the signals are locked-on to and tracked. A/D - Analog to Digital - The process of converting an analog signal to a digital signal. Almanac - An overview of data for all the satellites, including the satellite identity and location, satellite health, clock corrections and atmospheric delays. The almanac is necessary for satellite visibility calculations, to select the group of satellites offering the best geometry. Altitude aiding - A GPS operating mode used when the GPSSU is unable to track four or more satellites. In this mode inertial altitude inputs are used along with the earth's radius as the fourth range.
Autonomous - Independent or self-governing. An autonomous GPS system is one which stands alone and is NOT part of another system, like a GPS/IRS system. Clock bias - The difference between a true universal time and the time of the clock. Control segment - The GPS system is divided into segments. One of these is the control segment, which includes the control and monitor stations (one master station and five monitor stations. Constellation - A number of satellites considered as a group. Critical - The conditions which cause a fault to be declared. Conditions which are absolutely necessary for operation.
Algorithm - A step-by-step procedure for solving a problem; e.g. the procedure for finding the square root of a number.
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Appendix A (cont) Earth-centered coordinates -Coordinates of an earth-centered coordinate system, with the origin at the earth's center of mass (a WGS-84 system {World Geodetic System. 1984)). The z-axis is the rotation axis of the earth, the x-axis is the intersection of the WGS 84 reference meridian plane and the plane of the equator (parallel to the zero meridian), and the Y-axis is measured in the plane of the equator 90 degrees east of the axis, completing a right-handed, earth-centered coordinate system.
Ionosphere - A region above the earth's surface, in which solar radiation causes an ionized layer of charged particles to exist. This causes some delay in the transmission of radio signals from the satellites to user. Isolated - Set aside or apart from 9thers. The.GPS integrity monitor can isolate or exclude a failed satellite from the Kalman filter algorithm for determining position.
Estimate - To calculate the approximate value of a quantity. A Kalman filter estimates the position error of the GPS, by always using the difference between the last estimate and the last measurement to make a new estimate. GPS - Global Positioning System - A radio navigation system which uses a group of satellites orbiting the earth. The system is intended to provide highly accurate position and velocity in three dimensions and precise time on a global basis continuously. GPSSU - GPS Sensor Unit - A unit which receives radio navigation signals from satellites and calculates GPS position and time data. HIL - Horizontal Integrity Limit - An estimating term indicating what kind of accuracy the GPS is achieving, with a 99.9% confidence level. The integrity limit estimate is used when the GPS is not updating the GPS navigation position. It is a function of the time elapsed since the last GPS position update. It is a dynamic term.
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FLIGHT MANAGEMENT COMPUTER SYSTEM - INTRODUCTION 4 FLIGHT MANAGEMENT COMPUTER SYSTEM ............................ 7
FMCS - AUTOTHROTTLE DISCONNECT SWITCHES ................ 66 FMCS - FMC GO-AROUND SWITCHES ....................................... 68
FMC................................................................................................ 8 FMCS - MEC COMPONENT LOCATIONS .................................... 10
FMCS - FMC MASTER SWITCH AND NAVIGATION INSTRUMENT SOURCE SELECT SWITCHES (NAV ISSS) ........................... 70
FMCS - FLIGHT DECK COMPONENT LOCATIONS - 1 ............... 12 FMCS - FLIGHT DECK COMPONENT LOCATIONS - 2 ............... 14
FMCS - AIRBORNE DATA LOADER, ADL CONTROL AND DISKETTE STORAGE CASE ..................................................................... 72
FMCS - POWER ............................................................................ 24 FMCS - MASTER RELAY & A/T ARM POWER ............................. 26
FMCS - PRIMARY FLIGHT DISPLAY DATA .................................... 75 FMCS - NAVIGATION DISPLAY DATA ............................................ 78
FMCS - CDU AND DATA LOADER POWER ................................. 28 FMCS - INTERSYSTEM DATA ....................................................... 30
FMCS - MENU PAGE ..................................................................... 82 FMCS - IDENTIFICATION PAGE .................................................... 85
FMCS - DIGITAL SENSOR DATA ................................................... 32 FMCS - EIU AND EFIS C. P. INTERFACE...................................... 36
FMCS - INITIALIZATION/REFERENCE INDEX PAGE .................... 88 FMCS - POSITION INITIALIZATION AND POSITION REFERENCE
FMCS-IDU INTERFACE ................................................................. 38 FMCS - NAV SWITCH TO IDS INTERFACE .................................. 40
PAGES ..................................................................................... 91 FMCS - ROUTE PAGES ................................................................ 94
FMCS-NAVIGATION RADIO TUNING ............................................. 42 FMCS-AFDS INTERFACE ............................................................. 44
FMCS - DEPARTURE/ARRIVAL INDEX ......................................... 98 FMCS - DEPARTURES PAGE AND ARRIVALS PAGE .................. 101
FMCS - AUTOTHROTTLE INTERFACE ........................................ 46 FMCS - ENGINE TRIM INTERFACE .............................................. 48
FMCS - PERFORMANCE INITIALIZATION PAGE .......................... 104 FMCS - THRUST LIMIT PAGES ..................................................... 109
FMCS - MISCELLANEOUS INTERFACES..................................... 51 CREW ALERTNESS MONITOR.................................................... 54
FMCS - TAKEOFF REFERENCE PAGES ..................................... 112 FMCS - APPROACH REFERENCE PAGE.................................... 117
FMCS - CDU INTERFACES ........................................................... 56 FMCS - FLIGHT MANAGEMENT COMPUTER .............................. 58
FMCS - REFERENCE NAVIGATION DATA PAGE ......................... 121 FMCS - MAINTENANCE PAGES .................................................... 124
FMCS - CONTROL DISPLAY UNIT ................................................ 60 FMCS - AUTOTHROTTLE SERVOMOTOR GENERATOR .......... 64
FMCS - CLIMB PAGES .................................................................. 126 FMCS - CRUISE PAGES ............................................................... 131
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FMCS - DESCENT PAGES ........................................................... 137 FMCS - PROGRESS PAGES ........................................................ 142
FMCS - AUTOTHROTTLE CONTROL LAWS AND MODE LOGIC 220 FMCS - EICAS THRUST DISPLAY ................................................ 225
FMCS - HOLD PAGES ................................................................... 147 FMCS - ROUTE LEGS, ROUTE DATA AND WIND PAGES .......... 150
FMCS - PFD AUTOTHROTTLE MODE DISPLAY ......................... 228 FMCS - AUTOTHROTTLE FLIGHT PROFILE ............................... 231
FMCS - FIX PAGE .......................................................................... 155 FMCS - NAVIGATION RADIO PAGE ............................................... 159
FMCS - AUTOTHROTTLE OPERATION TAKEOFF...................... 234 FMCS - AUTOTHROTTLE OPERATION - VNAV CLIMB ............... 236
FMCS - IRS LEGS AND IRS PROGRESS PAGES ....................... 163 FMCS - ALTERNATE NAVIGATION RADIO PAGE ......................... 166
FMCS - AUTOTHROTTLE OPERATION - VNAV CRUISE ............ 238 FMCS - AUTOTHROTTLE OPERATION - VNAV DESCENT ........ 240
FMCS - FUNCTIONAL BLOCK DIAGRAM ..................................... 170 FMCS - NAVIGATION FUNCTION .................................................. 175
FMCS - AUTOTHROTTLE OPERATION - SPEED ....................... 242 FMCS - AUTOTHROTTLE OPERATION - FLIGHT LEVEL
FMCS - NAVIGATION RADIO TUNING ........................................... 179 FMCS - PERFORMANCE FUNCTION ........................................... 183
CHANGE ................................................................................... 244 FMCS - AUTOTHROTTLE OPERATION THRUST ....................... 246
FMCS - GUIDANCE FUNCTION .................................................... 189 FMCS - LNAV ENGAGE REQUIREMENTS .................................... 192
FMCS - AUTOTHROTTLE OPERATION - GO-AROUND ............. 248 FMCS - NAV DATA CROSSLOAD PAGE ....................................... 250
FMCS - VNAV ENGAGE REQUIREMENTS ................................... 194 FMCS - SPEED AND ALTITUDE INTERVENTION ........................ 197
FMCS - PERF FACTORS PAGE ................................................... 252 FMCS - IRS MONITOR PAGE ........................................................ 256
FMCS-EFIS FUNCTION ................................................................. 200 FMCS - CONTINUOUS FAULT MONITOR ..................................... 203
FMCS-BITE REPORT PAGE ......................................................... 258 FMCS - BITE AND SYSTEM TESTS ............................................. 261
FMCS-RESYNCHRONIZATION ..................................................... 206 FMCS - CDU MESSAGES ............................................................. 209
FMCS - BITE AND SYSTEM TESTS ............................................. 262 FMCS - FMC GROUND TESTS (SHEET - 1) ................................ 264
FMC - THRUST MANAGEMENT - INTRODUCTION ...................... 212 FMCS - THRUST MANAGEMENT FUNCTION ............................... 214
FMCS - FMC GROUND TESTS (SHEET - 2) ................................ 266 FMCS - MODE CONTROL PANEL GROUND TEST (SHEET 3) .. 268
FMC - THRUST LIMIT CALCULATION ........................................... 216 FMCS - AUTOTHROTTLE ENGAGE LOGIC ................................. 218
FMCS - CDU BITE AND FAULT MONITOR .................................... 270 FMCS - DATA LOADER OPERATION ........................................... 273
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FMCS - FLIGHT DECK EFFECTS ................................................. 276 FMCS - CMCS MESSAGES - 1 ..................................................... 278 FMCS - CMCS MESSAGES - 2 ..................................................... 280
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FLIGHT MANAGEMENT COMPUTER SYSTEM - INTRODUCTION General The flight management computer system (FMCS) does many functions and calculations which reduce crew workload. The major functions are: - Flight plan map display - Automatic navigation/radio tuning - Thrust Management - Lateral guidance (LNAV) - Vertical guidance (VNAV)
The FMCS calculates airplane position with inertial and radio data. ADF receivers are tuned manually through the CDU.
Thrust Management The FMCS moves the thrust levers to control the thrust of the engines. The FMCS also computes thrust limits and sends engine trim equalization commands to the electronic engine controls.
Flight Plan Map Display Lateral Guidance The FMCS does calculations which allow the flight crew to monitor airplane movement along the flight plan. The FMCS shows this data on the ND in the map and plan formats. The FMCS can also show additional data from the navigation data base on the map displays.
The FMCS gives lateral guidance to fly the airplane from point to point along the route.
Vertical Guidance/Performance Automatic Navigation/Radio Tuning The FMCS automatically tunes navigation radios (VOR, DME, ILS) along the route.
The FMCS gives vertical guidance to fly the airplane on the most economical path. Performance calculations provide predictions of flight data along the route.
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FLIGHT MANAGEMENT COMPUTER SYSTEM
General
CDU
The FMCS performs these major functions based on inputs from the flight crew through the CDU and data from external sensors:
The control display unit (CDU) is the primary interface between the flight crew and the FMC. If both of the FMCS fail, the CDU performs these backup functions:
- Performance Calculations - Alternate navigation using inputs from the IRUs - Guidance (LNAV and VNAV steering commands) - Alternate navigation radio tuning - Thrust management (autothrottle, thrust limits, and engine trim) - Navigation/radio tuning
The CDU may also be selected as the source for the map displays. This map is based on the last FMC update and can be selectd at any time.
- Map display - BITE The FMC also uses stored data to assist in calculation of lateral, vertical and thrust commands that control the airplane along the active route. The data loader interfaces with the FMCS to update the stored data.
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FMC The FMC stores the following data: - A navigation data base which contains data on items such as airports, procedures, waypoints and navaids. From this data base the FMC selects reference data to assist in calculations of present position and lateral guidance to the flight plan. This data base is updated every 28 days.
- Engine electronic controllers (EEC) for the engine trim function - Flight control computers (FCC) for autopilot/flight director commands - Mode control panel (MCP) for mode status and speed data
- A performance data base which contains models of the airplane and engine characteristics. From this data base the FMC selects reference data to assist in calculation of flight path projection and vertical guidance to the flight plan.
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- An operational program that determines which sensors are used for calculations and how the calculations are done.
Autothrottle Servomotor Generator The autothrottle servomotor receives commands from the FMC to move the thrust levers. The generator and EECs provide feedback.
FMC Master Relays A switch in the flight deck controls the FMC master relays. The position of the relays determine which FMC sends outputs to the:
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FMCS - MEC COMPONENT LOCATIONS
These are the components in the main equipment center (MEC): - Left and right FMC - Numbers 1, 2, and 3 FMC master switch relays
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FMCS - FLIGHT DECK COMPONENT LOCATIONS - 1
Captain’s Main Instrument Panel (P1)
Aft Electronics Panel (P8)
These are the components on P1:
The center CDU is on P8.
- Left inboard IDU (ND)
First Officer’s Main Instrument Panel (P3)
- Left outboard IDU (PFD)
These are the components on P3:
- Captain’s instrument source select switches
- Right inboard IDU (ND) - Right outboard IDU (PFD)
Forward Electronics Panel (P9) - First officer’s instrument source select switches These are the components on P9: - Right CDU
Autoflight Control Panel (P10)
- LOWER IDU (EICAS/ND)
These are the components on P10:
- Left CDU
- Left EFIS control panel - Right EFIS control panel - AFCS mode control panel 34.61.0704 -001
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FMCS - FLIGHT DECK COMPONENT LOCATIONS - 2
Control Stand The autothrottle servomotor generator is below the control stand and accessible from the right side. The thrust levers have switches for autothrottle disconnect/reset and go-around (TO/GA).
First Observer’s Console Panel (P11)
Main Power Distribution Panel (P6) These are the components on/in P6: - FMCS database loader CB - R7561 Trim enable relay
These are the components on P11: Overhead Circuit Breaker Panel (P7) - Data loader control panel - Airborne data loader - Diskette storage case
Pilots’ Center Instrument Panel (P2) These are the components on P2: - FMC master switch - HEADING REF switch - Upper IDU (EICAS)
These FMCS circuit breakers are on P7: - FMC left - CDU left - CDU center - A/T servo excitation - Auto flight warning - FMC right - CDU right - A/T servo right - FMC master switch 34.61.0705 -003
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FMCS - POWER
The APU standby bus (115v ac) sends power to the left FMC and the first officer’s transfer bus sends power to the right FMC. From this, the FMC power supply produces the power needed for calculation, logic, and control. Servo tachometer excitation comes directly from the first officer’s transfer bus. Servo motor excitation comes from the same bus but through the FMC selected as master. Bus 1 and bus 2, 28v dc provide autothrottle drive power. The 28v dc from the battery bus supplies power for the warning circuits in the FMCs. 34.61.0710 -004
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FMCS - MASTER RELAY & A/T ARM POWER
The FMC master relays are energized by the FMC master switch from 28v dc bus 1, if the FMC master switch is in the R position. The autothrottle arm voltage goes through both the FMC master switch and master relay. This is to make sure that the switch and relay are in the same position. If the associated master relay is not in the same position as the master switch, the autothrottle can not be armed. The L-FMC master logic power is through the deenergized closed contacts of master relay 1. The R-FMC master logic is through the deenergized open contacts of master relay 3. When the right FMC is selected as master the master relays are energized. The L-FMC loses 28v dc (master logic) and the R-FMC gets 28v dc (master logic) through the main energized contacts of master relay 3. 34.61.0712 -002
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FMCS - CDU AND DATA LOADER POWER
The standby bus, captain’s AC transfer bus and the first officer’s transfer bus supply power to the three control display units. Bus-1 sends power to the airborne data loader. The power line goes through the data loader control panel. 34.61.0804 -001
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FMCS - INTERSYSTEM DATA
General
CDU Alternate FMC Input Select
The basic FMCS consists of two flight management computers (FMCs) and three control display units (CDU). The two FMCs process data sequentially as it is received from the CDUs. The left and right CDUs are independent and can display different pages at the same time. The center CDU receives data from the FMCs, but cannot send data to the FMCs.
The NAV instrument source select switch controls which FMC input is used by a CDU for display control. The normal input to the left and center CDUs is the left FMC. The normal input to the right CDU is the right FMC. The onside NAV switch selects the offside FMC input. If one FMC fails, the CDUs can still display different pages when selected to the same FMC.
Button Push Master
Intersystem Data
Button pushes from the CDUs to the FMCs are processed in such a way as to prevent the FMCs from duplicating certain computations. In a normal dual system configuration, the left FMC is the button push master. All button pushes from either the left or right CDU are first processed by the left FMC. The left FMC passes the button push data through the intersystem bus to the right FMC. Button pushes that cause a change to the left CDU display are output by the left FMC, while button pushes that cause a change to the right CDU display are output by the right FMC.
The intersystem bus is used to maintain synchronization of the two FMCs. Information is compared between the two computers. Resynchronization can result from data comparison that exceeds normal tolerances. During resynchronization one FMC sends data to the other to allow normal operation to resume. If resynchronization is not successful a shutdown command can be sent by one FMC to the other. Resynchronization can be done by either FMC.
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FMCS - DIGITAL SENSOR DATA
General
Navigation Radios
Sensor data provides the FMCS with the data required to support the many calculations. The FMCS receives data from the following sensors:
The navigation radios provide the FMCS with radio position data. This data is used to compute airplane position. VOR receivers provide bearing and frequency data. ILS receivers provide localizer deviation and frequency data. DME interrogators provide distance and frequency data. The left FMC normally uses the left and right VOR, the left DME and the left ILS receiver, while the right FMC uses the right and left VOR, right DME and right ILS receiver. The FMCs switch to the offside DME input if the normal input is not valid.
- Fuel quantity indicating system - Navigation radios - Clocks - Inertial reference units
Clocks
- Air data computers
The clocks provide the FMCS with date and time. This data is used for the nav data base validity check and a GMT reference for time at waypoint and destination data. The FMCs have an internal time base which is initialized to the clock data. The FMCs normally use the captain’s clock. If the captain’s clock is not valid, the FMCs switch to the first officer’s clock.
Fuel Quantity Indicating System The fuel quantity processor unit provides the FMCs with total fuel quantity. This data is used to compute the airplane gross weight. The left FMC uses output A, while the right FMC uses output B.
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Inertial Reference Units The inertial reference units provide the FMCs with position, vertical speed, heading, track, and velocity data. The data is used in navigation and guidance computations. For position and velocity data the FMCs each use data from all three IRUs. If one IRU is not valid, the FMCs switch to the onside or center input. For data other than position or velocities, the IRU source seleciton is as follows: - The left IRU is used when no autopilot or flight director is engaged, only the left autopilot channel is engaged, only the captain’s flight director is engaged, or the left autopilot channel is first in command during multichannel operations.
- If no autopilot or flight director is engaged, or only the left or center autopilot channel is engaged, the FMCs select the ADC source based on the left ADC selected discrete. - If only the right autopilot channel is engaged, the FMCs select the ADC source based on the right ADC select discrete. - If the autopilot is in multichannel operation, the FMCs select the ADC source based on the channel that is first in command.
34.61.0806B-002
- The right IRU is used when only the right autopilot channel is engaged, only the first officer’s flight director is engaged, or the right autopilot channel is first in command during multichannel operation. - The center IRU is used when only the center autopilot channel is engaged, or the center autopilot channel is first in command during multichannel operation.
Air Data Computers The air data computers provide the FMCs with altitude, airspeed, temperature, and pressure data. This data is used in navigation and guidance computations. The FMC selection of air data inputs is selected as follows:
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34.61.0306 -002
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FMCS - EIU AND EFIS C. P. INTERFACE
The EIUs provide sensor data to the FMCS. The data is used for many different calculations. The following is a list of EIU low speed data to the FMCs: - Fuel flow - Fuel jettison data - Vmin and Vmax - Flap position - Landing gear position - Engine speed - Bleed discretes - Radio altitude - Wing gear tilt
simultaneously. The FMCs calculate many parameters for display and control. The FMCs send this general purpose data to the EIUs: - Thrust management data - Navigation radio frequencies - Speed tape data - Stabilizer trim data - Gross weight - Flight plan data - Miscellaneous data - BITE data The FMCs send an A/T disconnect discrete to the EIUs. This signal alerts the flight crew of an autothrottle disconnect.
The EIUs provide this high speed engine data to the FMCs: - Engine pressure ratios - Engine speed (N1, N2, N3) - Exhaust gas temperatures - Engine oil temperatures - Engine rating - Trim data For low speed data the EIU source is based on presence and validity monitoring. The priority of selection is left, center, and then right. The FMCs use all valid sources of high speed data
The EFIS control panel sends this information to each FMC and CDU: - Navigation display mode selection - Map range - Map data selector switches The information is used to control the separate map displays for the captain and first officer. The data goes through the onside CDUs and then to the FMCs. If an EFIS C. P. fails the CDU transmits the data and may be used as a back-up EIFS C. P. 34.61.0807 -001
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FMCS-IDU INTERFACE
The FMCs and CDUs send high speed map display data directly to the IDUs. Each FMC can produce a separate map display for the captain and first officer. The left output bus contains captain’s map data, while the right bus contains first officer’s data. The CDU can only produce one map display. The left CDU produces a captain’s map display. The right CDU produces a first officer’s map display. The center CDU can produce either a captain’s or first officer’s map display. Each IDU selects a map input bus based on the IDU position operating as a captain’s or first officer’s display and the position of the NAV instrument source select switches. Captain’s displays use the left NAV switch, while first officer’s displays use the right NAV switch. The outboard IDUs use the high speed data bus as their source of track and ground speed data.
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FMCS - NAV SWITCH TO IDS INTERFACE
The captain’s and first officer’s NAV switches send source select discretes to all three EIU’s. The source select discretes are used by the EIU’s to send source select commands to the IDU’s. The inboard and lower IDU’s use the source select commands to select the map display source from either of the FMCs or the onside or center CDUs. The outboard IDU’s use the source select commands to select the source of track data from either of the FMCs. 34.61.0817 -001
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FMCS-NAVIGATION RADIO TUNING
The master FMC normally sends frequency tuning data to the navigation radios. Tuning data is based on manual inputs from the CDUs or automatic selection done by the FMCS navigation function. Course entries by the flight crew are sent to the VOR receivers during certain modes of operation. Selected runway heading goes to the ILS receivers along with ILS frequency. The ILS receivers are parked by the FMCS when no auto or manual tuning is active. The DME interrogators receive up to five frequencies for directed scan operation along with audio and display bit assignment. The left and right ADF receivers get frequency and mode data based on CDU manual entries. If the master FMC fails in the air or both FMCs fail on the ground, the CDUs send a source select discrete to the navigation radios. This source select discrete allows manual tuning data from the CDU to tune the onside navigation radios. 34.61.0809 -001
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FMCS-AFDS INTERFACE
The AFCS MCP sends the following digital data to the FMCs: - Selected altitude - Selected heading - Selected airspeed/Mach - Flap position - Stabilizer position - Speed brake position - MCP pushbutton status - Altitude and speed intervention selection - TO/GA select The AFCS MCP sends an analog autothrottle arm discrete signal to each FMC. The AFCS MCP sends the system A bus to the left FMC and the system B bus to the right FMC.
The master FMC sends the following data to the FCCs: - LNAV steering commands - VNAV steering commands - Vertical speed commands - Airspeed limits The FCCs use the FMC data to control the airplane when the LNAV and VNAV modes are selected. The FCCs send a tune inhibit discrete to the FMCs and CDUs to prevent tuning of the ILS when any of these conditions exits: - A/P engaged and LOC or G/S capture - Below 500' during F/D only approach
The data from the AFCS MCP is used to control the autothrottle and for selection of the LNAV and VNAV modes. The master FMC sends the following data to the AFCS MCP:
- During takeoff acceleration through 40 knots until in air. 34.61.0810 -001
- Mode status - Speed data. This data is used by the AFCS MCP to light autothrottle mode buttons and to blank or display certain speeds in the selected airspeed window.
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FMCS - AUTOTHROTTLE INTERFACE
The autothrottle servomotor generator receives forward and reverse commands and an excitation voltage from each FMC. The FMCs can drive the autothrottle servomotor generator in an operating range from 0 to 10 degrees per second. The drive signal is an AC voltage developed by the FMC from the 28v dc servo power input. The excitation voltage is 115v ac. The autothrottle servomotor generator has dual windings, one for each FMC. The single tachometer feedback signal provides a rate feedback signal to each FMC. The FMCs receive an autothrottle disconnect discrete input and a reset discrete input from switches in thrust levers 1 and 4. The FMCs receive a go-around select discrete from switches in thrust levers 2 and 3. These switches are not used in favor of the voted go-around status provided by AFDS.
34.61.0811 -001
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FMCS - ENGINE TRIM INTERFACE
The master FMC sends the following data to the electronic engine controls: - EPR/N1 trim command - Bleed correction Engine trim is enabled at the FMCs by the autothrottle arm discrete from the AFCS MCP. The autothrottle arm discrete also controls the trim enable relay. This relay sends a trim enable discrete to the electronic engine controls. 34.61.0812 -001
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34.61.0312 -001
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FMCS - MISCELLANEOUS INTERFACES
General
Air/Ground Relays
The FMCs have the interfaces with the following to support various functions:
The air/ground relays send an analog discrete to enable data base loading, and is also used in flight phase determination.
- Heading reference switch - FMC master relays - Central maintenance computer - Air ground relay - Cabin pressure controllers - Modular avoinics and warning electronics assembly - Airborne data loader - Inertial reference units - Ground proximity warning computer - Weight and Balance Computer (WBC) Heading Reference Switch
Cabin Pressure Controllers The cabin pressure controllers get active flight plan landing altitude and vertical profile data. Modular Avoinics and Warning Electronics Assembly (MAWEA) The stall warning management computers in the MAWEA get gross weight and center of gravity data from the FMCs. 34.61.0813A-002
The heading reference switch selects magnetic or true reference for the map displays and guidance function. FMC Master Relays The FMC master relays send an analog discrete to enable one FMC to perform the master functions of radio tuning, thrust management, and guidance.
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Airborne Data Loader The airborne data loader allows the navigation data base or operational program to be updated on the airplane. The airborne data loader can also be used to record the FMC BITE report. The data goes through the data loader control panel, which also sends data base load enable discretes to the FMCs when selected by the data loader selector switch.
Inertial Reference Units Inertial reference units get present position latitude and longitude for position initializaiton during alignment. The inertial reference units also get reference heading when operating in the attitude mode.
Ground Proximity Warning Computer The ground proximity warning computer gets present position and track data from the left FMC. Weight & Balance The weight and balance computer sends gross weight and center of gravity data to both FMCs. This information shows on the performance initialization and takeoff reference pages.
34.61.0813B-002
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CREW ALERTNESS MONITOR
Purpose The FMC has a crew alertness monitor function which checks for pilot activity by monitoring for changes to the state of various discrete input and annunciates crew inactivity by setting the appropriate annunciation. This function will be customized for each airline by using data stored in an airline policy custom file in the navigational data base.
T2 = Duration of detected crew inactivity in descent prior to setting the advisory annunciation is 5 minutes.
Activity Monitor The FMC will monitor for a change in state to various inputs from the MCP, EFIS control panel, EICAS control panel, VHF/HF radio, MCDU and CDU to determine crew activity. The time allowed between crew inactivity during the cruise or descent profile is set by the airline but should not exceed the minimum or maximum listed below. If a time limit is exceeded, a digital discrete is sent to the EIU's. The message PILOT RESPONSE (level C advisory annunciation) will be displayed. Timer logic for the crew alertness monitor will be defined in the airline policy custom file of the navigational data base. T1 = Duration of detected crew inactivity in cruise (>FL200) prior to setting the advisory annunciation is 54 minutes.
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FMCS - CDU INTERFACES
General
Outputs
The CDUs receive data from these:
The CDU sends a DME audio pairing discrete to the audio management unit (AMU). The AMU uses this discrete to pair DME audio with either ILS or VOR audio.
- Left, center, and right IRUs - Left CMC - Left, center, and right FCCs - Heading reference switch
The CDU also sends a weather radar (WXR) on discrete to the WXR control panel . This discrete responds to selections made on the alternate EFIS control panel function of the CDU. 34.61.0816 -001
IRU Each CDU receives present position, accelerations, ground speed, inertial altitude and vertical speed, attitude and heading. This data is used for the alternate navigation function of the CDU.
FCC The FCCs send an analog input to the CDU to inhibit ILS tuning.
Heading Reference Switch The normal or true heading discrete selection is sent to the CDUs for navigation display orientation.
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FMCS - FLIGHT MANAGEMENT COMPUTER
Purpose The FMC processes requests from the crew and sensor data to navigate along the selected route, supply display data, and provide guidance outputs.
- A power supply to support internal processing.
Front Panel General The front panel has these features: The FMC contains hardware and software to support the processing of data. The FMC contains:
- An INITIATE TEST/LAMP TEST switch starts the self-test.
- Two SDP-185 processors to do calculations and data processing.
- An FMC FAIL red LED fault annunciator.
- Nonvolatile memory for storage of programs and data bases.
- A TEST IN PROCESS yellow LED annunciator that is on during test.
- Receiver subsystem to receive data from external systems. - Transmitter subsystem to transmit data to the external systems.
BITE/Monitor
- One autothrottle (A/T) servo card to perform the autothrottle I/O interfaces.
The FMC contains hardware and software to do power-up and continuous BITE to monitor operation and store faults.
- Two relays supply excitation power to the A/T servomotor. 34.61.0723 -001
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34.61.0223 -001
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FMCS - CONTROL DISPLAY UNIT
Purpose The control display unit (CDU) has an interface with the crew, external sensors, external systems and the FMC. The CDU controls and shows FMCS data.
General The CDU contains:
- Photocells for automatic CRT brightness control The primary control interface to the CDU is the keyboard. There are four types of keys: - Function keys - Mode keys - Line select keys - Alpha-numeric keys
- Keyboard for data entry or display selection - Cathode ray tube (CRT) to show data
Function Keys
- SDP-185 processor to control the operation of the CDU
The function keys are:
- ARINC transmitters to send data to the FMC and other users
- Execute (EXEC) is used to execute (make active) a function or change a function. The key has a light that comes on when the execute command is needed.
- Annunciators to show mode key status
- NEXT PAGE is used to look at the next page among many pages
- Brightness adjustment for manual CRT brightness control
- Previous page (PREV PAGE) is used to look at the last among many pages
- ARINC receivers to receive data from the FMC and other sources
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Mode Keys
Alpha-numeric Keys
The mode keys select the first page of a desired function. The mode keys are:
The alpha-numeric keys provide the means to enter data into the FMC. In addition to the letters and numbers, there are:
- Initialization/reference (INIT REF) - Route (RTE) - Departure/arrival (DEP ARR) - Vertical navigation (V-NAV) - FIX - LEGS - HOLD - Progress (PROG) - MENU - Navigation radio (NAV RAD) The function and operation of the modes and pages will be discussed later.
- Slash (/) key - Change sign (+/-) key - Delete (DEL) key - Clear (CLR) key - Space (SP) key The CLR key is used to clear (remove data from) all or part of the scratch pad. The DEL key enters the word DELETE in the scratch pad. A line select key then deletes (removes) the selected field.
34.61.0724B-001
Line Select Keys The line select keys (1L - 6L and 1R - 6R) are used to insert data from the scratch pad, to select data into the scratch pad or to select a function.
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Display Format 34.61.0724C-001
There are 14 lines of data which can be shown. Each line is 24 characters long. The top line is always the title of the page or function, the page number and the number of pages in that function. The bottom line is for the scratch pad. The scratch pad is used for data entry or transfer and for messages to be shown. Annunciators The annunciators come on to show status annunciations that require crew attention. These are: - Message (MSG) shows when an FMCS message is in the scratch pad - Display (DSPY) shows that the current page is not related to the active flight plan leg or present active mode. The DSPY light comes on, as an example, when the route page 2 of 3 (2/3) shows on the CDU and the aircraft is at the departure runway. - FAIL shows when either the master FMC fails in the air or the navigation instrument source selected FMC fails. NOTE: CDU considers in air when ground speed greater than 100 knots or ground speed is invalid. - Offset (OFST) shows that an offset route is in use when in the air.
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FMCS - AUTOTHROTTLE SERVOMOTOR GENERATOR
General The autothrottle servomotor generator is under the control stand. The FMC sends commands to the autothrottle servomotor to drive the throttles forward or aft through a gearbox assembly.
Operations Power to the autothrottle servomotor generator is 115 volts ac excitation and a variable ac signal derived from 28 volts dc for drive control. The generator also uses 115 volts ac for servomotor rate feedback to the flight management computer (FMC). The servomotor moves at 10 degrees/second maximum throttle rate when commanded.Access Access to the autothrottle servomotor generator is through the access panel on the first officer’s side of the control stand. The assembly is at the floor level below the control stand. 34.61.0725 -001
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FMCS - AUTOTHROTTLE DISCONNECT SWITCHES
General The autothrottle disconnect switches are on thrust levers No. 1 (S7 and S8) and No. 4 (S9 and S10).
Operation The autothrottle disconnect switches disconnects the autothrottle servomotor if it is engaged, and resets the EICAS caution message when a disconnect occurs.
Access Access to autothrottle disconnect switches is through a cover plate on the thrust levers.
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34.61.0226 -001
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FMCS - FMC GO-AROUND SWITCHES
General These switches are used to select the takeoff mode or the go-around mode.
Access Access to the autothrottle switches is through the switch cover plate on the thrust levers.
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34.61.0227 -001
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FMCS - FMC MASTER SWITCH AND NAVIGATION INSTRUMENT SOURCE SELECT SWITCHES (NAV ISSS)
General
Operation
The master switch determines which FMC provides:
The master switch - in the left FMC position causes the master relays to de-energize and connects the left FMC outputs to the FCCs, EECs, NAV radios and MCP. When the switch is in the right position the master relays energize and connects the right FMC outputs.
- Steering commands to the autopilot - Frequency commands to the NAV radios - Engine trim commands to the engine electronic computers (EECs)
NAV ISSS - sends discretes to the FMC, CDU, EFIS and EIU (EFIS/ EICAS interface unit) for navigation source selection. The captain and first officer may select the same NAV source.
- Mode control panel (MCP) data - Autothrottle (A/T) commands to the A/T servo NAV ISSS - selects the onside EFIS (electronic flight instrument system) navigation source. The FMC provides navigation data to the PFD (primary flight display) and ND (navigation display). The CDU provides navigation data to the ND only. The NAV ISSSs also select the FMC for CDU map and display update.
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Access Master switch - the master switch is on the P2 instrument panel. NAV ISSSs - the NAV ISSSs are on the instrument source select modules (ISSM) which are then located on the P1 (captain) and P3 (first officer) panels. 34.61.0728 -001
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FMCS - AIRBORNE DATA LOADER, ADL CONTROL AND DISKETTE STORAGE CASE
General
Diskette Storage Case
Data bases and operational programs can be loaded in many of the systems in the airplane. This is done with the installed airborne data loader (ADL) and the ADL control panel (on P11 behind the first officer). A diskette storage case is used to store preloaded and future loadable programs.
The diskette storage case is mounted above the ADL control panel in the P11 book case. The storage case provides storage capability for up to fourteen 3.5 inch diskettes. The unit door is hinged, transparent and made of a plastic material.
ADL Control Panel ADL Control Power input is 115v ac BUS 1. Control is with the data loader interface panel switch. Power is supplied from the FMCS data base loader circuit breaker on P6-4.
The ADL control panel is installed on the P11 book case below the diskette storage case and above the ADL unit. The unit houses a rotary switch that allows LRU selection for software enabling and loading from the ADL. 34.61.0729 -003
ADL Physical Description The ADL is installed in the P11 panel below the data loader control panel. It has a front cover panel that covers the display lights and the 3.5 inch diskette slot.
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FMCS - PRIMARY FLIGHT DISPLAY DATA
General The FMCS sends speed tape data, autothrottle mode, and drift angle to the PFD.
- Rotation Speed (VR) shows as a green ‘VR’ next to the rotation speed, or as ‘R’ when closer than four knots to the decision speed.
Speed Tape Data
- Landing Speed (V REF) shows as a green ‘REF’ next to the landing speed.
The following FMCS data shows on the airspeed tape: - Minimum Manuever Speed shows as an amber line which begins at the minimum manuever speed on the tape and extends to the stick shaker speed. Minimum manuever speed is the lowest speed the FMC may use for control signals. - High Speed Buffet Speed shows as an amber line which begins at the high speed buffet speed on the tape and extends to the maximum operating speed. High speed buffet speed is the maximum speed the FMC may use for control signals.
- Flap Manuever Speeds show as green digits next to the speed at which a flap setting applies. Flap retraction to zero units shows as ‘UP’. - Selected Target Speed shows as a magenta readout at the top of the tape and a magenta cursor on the tape. This data normally comes from the AFDS, but comes from the FMCS when VNAV is engaged. Selected target speed is set to the V2 value for takeoff. 34.61.0730A-004
- Decision Speed (V1) shows as a green ‘V1’ and digital readout at the top of the tape when the value of V1 is off-scale. When the value of V1 is within the range of the scale, ‘V1’ shows next to the decision speed.
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Autothrottle Mode Annunciation The autothrottle mode shows in green on the PFD in the upper left corner when the autothrottle is engaged. A green box shows around the mode for ten seconds after a mode change occurs.
FMC is invalid, the source of track defaults to the selected IRU.
PFD Data Source Selection Heading
Source selection of PFD data is as follows: - Speed tape data is normally supplied by the onside FMC and the secondary source is the offside FMC
The source of heading is normally selected by the onside IRS instrument source select switch, but can be changed based on data from the FMCS. At high latitudes, the FMCs each use a single IRU source. Track from one IRU may be poorly correlated with heading from a different IRU when close to the pole, if the IRU positions differ by a few miles. The PFD and ND always use heading data from the same source which the FMC is using for track.
- Autothrottle mode data is supplied by the master FMC
Touch Down Zone
- Landing altitude data is normally supplied by the master FMC. If the master FMC is not valid, the data comes from the cabin pressure control system.
Touch down zone shows as an amber mark on the altitude tape. Indicating the landing altitude. Shows NO TDZ when there is no FMC or cabin altitude information.
- Drift angle data is normally supplied by the selected FMC and the selected IRU as secondary
34.61.0730B-004
Drift Angle Pointer (Track) The source of track data is normally the selected FMC. Below 80 knots, heading data is substituded for track data. If the selected
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FMCS - NAVIGATION DISPLAY DATA
General
Wind Data
The selected FMC/CDU sends map and display data to the ND.
Wind data (direction, speed and angle) shows when true air speed (TAS) is greater than 100 knots and wind speed is greater than 5 knots. The selected FMC normally shows this data. The selected IRU shows this data when the selected FMC is not valid.
Track (MAG/TRU) The source of track data is normally the selected FMC. Below 80 knots, IRS heading data is substituded for track data. If the selected FMC is invalid, the source of track defaults to the selected IRU. The source of heading is normally selected by the onside IRS instrument source select switch, but can be changed based on data from the FMCS. At high latitudes, the FMCs each use a single IRU source. Track from one IRU may be poorly correlated with heading from a different IRU when close to the pole if the IRU positions differ by a few miles. The PFD and ND will always use heading data from the same source which the FMC is using for track.
Active Waypoint The magenta active waypoint symbol is the waypoint the airplane is flying to. When the airplane passes over the active waypoint it becomes white and the next flight plan waypoint goes from white to magenta. The source for this data is the selected FMC or the selected CDU. 34.61.0731A-001
Ground Speed The selected FMC normally shows this data. The selected IRU shows this data when the selected FMC is not valid.
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Range to Altitude
Altitude Profile Points
The range to altitude arc shows as the airplane approaches the mode control panel (MCP) selected altitude. The arc position is based on present flight path angle.
Altitude profile points are along the flight plan where the flight mode or vertical path changes. These are:
Vertical Deviation The vertical path deviation scale and magenta pointer show on the right side of the ND when the airplane passes the top of descent altitude profile point. The vertical deviation scale has a full scale range of +/- 420 feet. The deviation also shows as a digital readout calibrated in 50-foot increments to a maximum of 9999 feet when the pointer is at the upper or lower limit of the scale.
- Top of climb (T/C) - Top of descent (T/D) - Step climb (S/C) - End of descent (E/D) These points show as small green circles.
Flight Plan The flight plan shows in three ways:
Estimated Time of Arrival (ETA)
- Active flight plan - solid magenta line
The time that shows is when the airplane will reach the active waypoint. When a CDU is selected as the display source it shows time-to-go.
- Inactive flight plan - dashed cyan line
Distance To Go
- Flight plan modifications - dashed white lines
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The distance to the active waypoint, in nautical miles, shows below the ETA.
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Radio Update The radio position update display shows the radio position update mode. These are: - VD (VOR/DME) - DD (DME/DME) - LOC (LOCALIZER)
directional trend based on position, ground speed and cross track acceleration. The trend vector segmented line(s) shows the airplane’s position in 30, 60 and 90 seconds. The map range determines how many trend vector segments show on the ND.
Map Data Selections IRS Position Update The IRS position update mode shows how many valid IRU inputs the FMC uses to calculate airplane position and velocity. The possible FMC IRS position update modes are: - IRS (3) - IRS (L) - IRS (C) - IRS (R) A change to/from IRS (3) to any of the other mode causes a green (box) to show around the display for ten seconds.
Map data selector switches on the EFIS control panel add or remove data from the map display. The EFIS control panel has these selections: - STA displays navaids. - WPT displays waypoints. - ARPT displays waypoints. - DATA displays flight waypoint data. - POS displays position check data.
34.61.0731C-001
Trend Vector The trend vector helps the pilot intercept a course/path and shows the degree of airplane turn. The trend vector shows the airplane’s
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FMCS - MENU PAGE
General This page provides MENU selection of the systems that use the CDU.
CDU, and shows beside the system that desires communication with the CDU.
Page Access
The MENU page shows next to shows. Push the key and the ALT EFIS CP page shows.
MENU Page
- (2R) If the EFIS CP fails, SELECT> shows. Push the key and the ALT EICAS CP page shows.
The function of the page is discussed by the operation of each line.
34.61.0732 -001
- (1L through 6L) The appropriate system prompt is shown when the system is operational. If a system is not operational, the prompt is not shown. Select the prompt to show the system’s initial page. When a system desires to use the CDU for communications, an EICAS message is shown. The MENU button should then be pushed to show the MENU page. When the MENU page shows, shows beside the system that is currently using the
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FMCS - IDENTIFICATION PAGE
General The identification (IDENT) page allows review of the FMC data base and program configuration.
- (4L) OPERATIONAL PROGRAM NUMBER line shows the operational program and performance data base part number. The last powered FMC locks on this page if this is different than the other FMC.
Page Access Push these line select keys to gain access to the IDENT page: - 1L on the MENU page
- (5L) DRAG/FUEL FLOW FACTOR line shows the fuel mileage factor assigned to drag and fuel flow, shown as a percentage. New values may not be entered on this page. However, new values may be entered by maintenance personnel on a maintenance page.
- 1L on the INIT/REF INDEX page (IDENT) - (6L) this key selects the INDEX page. IDENT Page The function of this page is discussed by the operation of each line: - (1L) MODEL NUMBER is the airplane model as read from the airframe/engine program pins. If the program pins do not match the stored performance data base, the line is blank.
- (1R) ENGINE IDENTIFICATION line shows the engine identification number as read from the airframe/engine program pins. If the program pins do not match the stored performance data base line is blank.
34.61.0734A-004
- (2L) NAV DATA line shows the data base identifier. If the data base did not load (receive) correctly, this line is blank.
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IDENT Page (cont)
- (2R and 3R) NDB EFFECTIVITY shows the active and inactive data bases in the FMC. These two lines show the dates through which they can be used. The lines can be interchanged (by the line select keys). When this is done, the data base shown in line 2L is the active data base. Selection can only be done on the ground. - (4R) SPARE ENG line shows in the header line and ACTIVE shows in the data line if the FMC is advised of a spare engine carry by the Air Data Computer (ADC). - (5R) CO DATA line shows the airline policy file identifier in large font. - (6R) POS INIT line shows the next page that needs data input for preflight completion. 34.61.0734B-004
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FMCS - INITIALIZATION/REFERENCE INDEX PAGE
General The initialization/reference (INIT/REF) index page provides access to the pages of data required for initialization of the FMC and IRS.
page. - (6L) APPROACH: this key allows access to the approach reference page.
Page Access Push the INDEX (6L) line select key on any INIT/REF page to get the INIT/REF index page.
INIT/REF INDEX Page The function of this page is discussed by the operation of each line.
- (1R) NAV DATA: this key allows access to the navigation data page. - (6R) MAINT: this key allows access to ground maintenance pages; crossload, perf factors, IRS monitor, and BITE report. This prompt is shown only on the ground. 34.61.0733 -001
- (1L) IDENT: this key allows access to the identification page. - (2L) POS: this key allows access to the position initialization page. - (3L) PERF: this key allows access to the performance initialization page. - (4L) THRUST LIM: this key allows access to the thrust limit page. - (5L) TAKEOFF: this key allows access to the takeoff reference
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FMCS - POSITION INITIALIZATION AND POSITION REFERENCE PAGES After GPS modification the FMC POS INIT and POS REF pages are effected. The changes of these pages are discussed in this paragraph.
POS INIT 1/3 (5L) UTC: both CDUs show the left or right GPS or the left or right clock time if it is valid, in that order. If GPS is the source it will display UTC (GPS), otherwise it will display UTC (MAN). (4R) Displays GPS position.
POS REF 2/3 (1L) Displays FMC position. Line title displays source in use for calculating the FMC position. Title options are GPS L, GPS R, LOCGPS L, LOC-GPS R, RADIO, LOC-DD, LOC-VD and LOC. (3L) Displays the Required Navigation Performance (RNP) and Actual Navigation Performance (ANP). RNP is airspace required navigation accuracy expressed in NM. Where applicable, RNP airspace values are published in the Route Documentation. The FMC uses default values. Default RNP is displayed in small font.
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Default values are: - Take-off - Ocean/Remote - Domestic - Terminal area - Approach
1.00NM 12.00NM 2.00NM 1.00NM .50NM
Manual entry appears in large font. Valid RNP entry range is from 0.01 to 99.9. Actual Navigation Performance (ANP) is a complex probability computation of navigation accuracy expressed in NM. The displayed ANP value is highly dependant on availability position input source (GPS, Radio, or IRS only). In 95% of the cases the real airplane position will be within the displayed ANP. (5R) GPS NAV. Defaults to INHIBIT following flight completion, allowing GPS updating. Push (when INHIBIT is displayed): ENABLE will be displayed. Inhibits GPS data for FMC position updating. Rtained through power interruption.
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PUSH (when ENABLE is displayed): INHIBIT will be displayed. Enables GPS dat for FMC position updating
POS REF 3/3 (4/5L) Displays position when computed by the indicated system. LAT/LON displays can be line selected to the scratchpad. Header and dat lines will be blank if GPS INHIBIT is selected.
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FMCS - ROUTE PAGES
General The route (RTE) page allows a route to be entered in the FMC. A route consists of: Origin, at least one waypoint and a destination.
change of the origin airport to another airport or a re-enter of the same origin airport removes the present route from the FMC. When the airplane is in flight, the origin airport can not be changed.
Page Access To access the RTE page:
- (3L) RUNWAY, any runway may be entered for the origin airport. A runway can also be selected through the DEPARTURES page. This shows automatically in this line.
- Select the RTE mode key - Line select ROUTE from POS INIT, POS REF or TAKEOFF REF pages
34.61.0736A-001
- Line select RTE 1 from RTE 2 page - Line select ROUTE from DEP/ARR pages.
RTE page The function of this page is discussed by the operation of each line: - (1L) ORIGIN shows box prompts when no origin is entered. A valid entry is any ICAO airport identifier in the NAV data base. A
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RTE page (cont) - (4L through 5L) VIA line shows departure/transition identifiers, airway identifiers, arrival/transition identifiers or DIRECT. Departure/transition identifiers and arrival/transition can be entered from the DEPARTURES page or from the ARRIVALS page or a company route can be entered. DIRECT shows when there is a TO entry (see line 4R). - (6L) RTE 2 shows on all pages except MOD pages. - ERASE shows on MOD pages. When ERASE is selected, all modifications (MOD) are removed and the display returns to the active RTE page. - (1R) DEST shows box prompts when no destination is entered. A valid entry is any airport identifier in the NAV data base. - (2R) FLT NO shows the company flight number that is entered. The display goes blank at power up or when the flight is completed.
- (4R through 5R) TO shows navaids or waypoint identifiers in the NAV data base. Entry is through the keyboard or by selection of a company route. Entries are also sent to the LEGS pages. When more than one waypoint have the same code, the SELECT DESIRED WPT page shows to allow selection. - (6R) ACTIVATE shows only on non-active route pages. Select this prompt to cause the EXEC key light to come on. When the EXEC key is pushed, the entered route becomes the active FMC route. When the FMC route is active while on the ground, this line is replaced with a PERF INIT or TAKEOFF prompt. - OFFSET shows only on the active or MOD pages when the plane is in the air. The pilot may enter a left or right offset of up to 99 nm. (for example; L45). The offset path extends to the end of route waypoint, or to the beginning of an approach procedure, route discontinuity or holding pattern. 34.61.0736B-001
- (3R) CO ROUTE (company route) is a specific code (up to 10 characters) that identifies a flight plan in the NAV data base. Entry of a CO ROUTE code causes the FMC to show the code on this line and the inactive flight plan on this page(s). This line can not be changed when the airplane is in the air.
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RTE Page (cont) DIR/INTC cancels the entered offset. Also, enter 0 in 6R, or select DELETE to cancel the offset (To cancel OFFSET, EXEC must be pushed).
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FMCS - DEPARTURE/ARRIVAL INDEX
General The departure/arrival (DEP/ARR) pages help to build a flight plan route. The pages give a menu of the departure and arrival procedures for the origin and destination airports. When a procedure is selected, it is put directly in the route.
Page Access
- (3L) < DEP: this key selects the departure page for the origin of RTE 2. - (6L) DEP: this key selects the departure page for the airport identifier entered in the scratch pad. - (1R) ARR >: this key selects the arrival page for the origin of RTE 1.
To access this page: - Push INDEX line select from DEPARTURE or ARRIVAL page
- (2R) ARR >: this key selects the arrival page for the destination of RTE 1.
- Push DEP/ARR mode key when no flight plan is active, or if an inactive RTE or LEGS page is presently shown
- (3R) ARR: this key selects the arrival page for the origin of RTE 2.
DEP/ARR Index The function of this page is discussed by the operation of each line. - (1L) < DEP: this key selects the departure page for the origin of RTE 1.
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- (4R) ARR: this key selects the arrival page for the destination of RTE 2. - (6R) ARR: this key selects the arrival page for the airport identifier entered in the scratch pad. 34.61.0737 -001
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FMCS - DEPARTURES PAGE AND ARRIVALS PAGE
General These pages give departure procedures from the selected origin airport and arrival procedures to the selected destination airport.
Page Access To access the DEPARTURE page, select the DEP/ARR mode key when the airplane is on the ground if there is an active route. To access the ARRIVAL page, select the DEP/ARR mode key when there is an active route and the airplane is in the air. When the airplane is less than 400 nm from the departure airport, or less than halfway along the active route (whichever is least), arrival procedures for the departure airport show. Otherwise, arrival procedures for the destination airport show on the display.
in the route. If a runway is selected, only the SIDs related to that runway are shown. Selection of a SID results in display of the departure page (that SID is shown on line 1L). SEL shows it is selected. A list of route transitions related to that SID are also shown (starts on line 2L). Selection of a transition results in display of the departure page with the transition shown on line 2L. SEL shows it is selected. The EXEC switch light comes on if it is not already on. - (6L) INDEX: line selection of the INDEX prompt results in the display of the DEP/ARR INDEX page.
34.61.0738A-001
Departures Page The function of the page is discussed by the operation of each line. - (1L through 5L) When the page is initially shows, standard instrument departures (SID) in the data base for the specified airport are shown. SEL or ACT labels show that a SID is already
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Departures Page (cont) - ERASE: the ERASE prompt shows after selection has occurred and before the EXEC switch is pushed. Select the ERASE prompt to remove any selections made from this page since the last EXEC action. - (1R through 5R) When this page initially shows, runways in the data base for the specific airport are shown. SEL or ACT labels show that there is a runway already in the route. If a SID is selected, only the runways related to that SID are shown. Selection of a runway results in display of the departure page with that runway shown on line 1R. SEL shows it has been selected. All SIDS related to the selected runway are also shown. The EXEC switch light will come on if it is not already on. - (6R) ROUTE: select this key to show the RTE 1 or 2 page.
Arrivals Page This page is nearly the same as the DEPARTURES page. The difference is that this page has arrivals to the destination airport and standard terminal arrival routes (STARs).
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FMCS - PERFORMANCE INITIALIZATION PAGE
General The performance initialization (PERF INIT) page is used for initialization of the FMC for performance (VNAV) calculations. It is part of the pre-flight sequence.
Page Access To access the PERF INIT page: - Push the INIT/REF mode key on the ground when the IRS position has been initialized - Push the PERF INIT line select key from the ACT RTE or TAKEOFF REF pages
fuel weight on line 3L. Both lines 1L and 3L show in large font. This line goes blank when fuel weight is not valid. If the weight and balance system (WBS) gross weight is valid, the header to this line is GR WT ADV. If the WBS gross weight is not valid, the header is GR WT. - (2L) FUEL: this line normally shows the FMC calculated (CALC) fuel quantity. When the airplane is on the ground before engine start, the FMC calculated fuel quantity is set equal to the airplane fuel totalizer system value. 34.61.0739A-008
- Push the PERF line select key from the INIT REF INDEX page
PERF INIT Page The function of this page is discussed by the operation of each line. - (1L) Gross weight (GR WT) entered or selected (ADV - advisory) on this line results in calculation and display of zero
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PERF INIT Page (cont) After engine start, the calculated fuel quantity comes from the totalizer value minus the integrated fuel flow. If at any time the fuel flow values become invalid for greater than 2 minutes, the calculated value will be invalid. The fuel totalizer system value is then used for FMC calculations and shows in line 2L as SENSED. Also, if there is a difference more than 9000 pounds (4091 kilograms) between the calculated fuel quantity and the fuel totalizer system value, the value shown will be the SENSED fuel totalizer system value. Entry results in the display of this value as a MANUAL value. The MANUAL entry is then updated by integrated fuel flow.
company route is entered that has this cost index number, or a manual entry. This number may be changed. - (6L) INDEX: this key selects the INIT REF INDEX page. - (1R) CRZ ALT: entry into this line is made from this page or from the climb or cruise pages. Change of altitude on this page is not allowed when the airplane is in the air.
34.61.0739B-008
Box prompts show when fuel quantity is invalid prior to engine start at 2L. MANUAL shows at 2L when a scratch pad entry is completed. Manual entry of a fuel quantity value will have priority over the fuel totalizer system input until the flight is completed. - (3L) ZERO FUEL WT: entry into this line results in the calculation and display of gross weight (line 1L). - (4L) RESERVES: this line shows prompt boxes until a value is entered. - (5L) COST INDEX: box prompts are shown on this line unless a
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PERF INIT Page (cont) - (4R) CRZ CG: shows a default or pilot entered cruise CG value. The default comes from the Performance Data Base and shows in small font. A pilot entered value shows in large font. The valid range is within and includes the CG minimum and CG maximum values. - (5R) STEP SIZE: this line shows the climb altitude increment that is used for the optimum step profile. Entries are from 1000 feet to 9000 feet. The default value is ICAO. - (6R) THRUST LIM: selection shows the thrust limit page.
34.61.0739C-008
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FMCS - THRUST LIMIT PAGES
General The thrust limit (THRUST LIM) page allows selection of thrust limit modes. It also has the capability to derate the engines for reduced thrust.
Page Access When the airplane is on the ground or has a TO thrust limit mode selected, this page can be selected from INIT/REF INDEX, PERF INIT, TAKEOFF REF or APPROACH REF pages.
THRUST LIM Page (GROUND or TAKEOFF Mode) The function of this page is discussed by the operation of each line:
for thrust derate. Temperature entry is in degrees centigrade or degrees Fahrenheit (if followed by an F). - 2L TO shows selected () status of the takeoff (TO) thrust limit modes. This may be selected when on the ground. TO mode is automatically selected on the ground. - (6L) INDEX selects the INIT/REF INDEX page. - (1R) THRUST MODE, EPR LIMIT shows the selected thrust limit calculated by the FMC thrust management function. Entry of a temperature in 1L that reduces the thrust limit causes a D to show in the header line and on the main EICAS display. 34.61.0740A-005
- shows for the present thrust limit mode (also shown on EICAS). - shows for the appropriate climb thrust limit mode when a takeoff thrust limit is selected (). - (1L and 1C) SEL and OAT shows outside air temperature in °C from the ADC. Line 1L shows the entered assumed temperature
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THRUST LIM page (GROUND or TAKEOFF Mode (cont) - (2R through 4R) CLB, CLB 1 and CLB 2 shows arm () status of the climb or derated climb thrust limit when a takeoff mode is selected (). The armed climb mode becomes selected at the thrust reduction altitude. (The thrust reduction altitude is displayed on the TAKEOFF REF page). If the airplane is above 400 feet AGL, push the thrust button on the MCP to change the armed CLB mode to selected .
- (6R) APPROACH selects the APPROACH REF page. 34.61.0740B-005
- (6R) TAKEOFF selects the TAKEOFF REF page.
THRUST LIM Page (Airborne) Most line select keys for this page are the same as the ground or takeoff mode THRUST LIM page except: - (2L) GA selects the go-around thrust limit mode. The go-around thrust limit mode is automatically selected during approach. - (3L) CON selects the maximum continuous thrust limit for the thrust limit mode. - (4L) CRZ selects cruise (CRZ) as the thrust limit mode. If it shows on the PERF FACTORS page, CRZ is automatically selected after FMC mode transition at top of climb (T/C) if VNAV is engaged.
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FMCS - TAKEOFF REFERENCE PAGES
General Entry or validation of takeoff speeds (V1, Vr, V2) center of gravity (CG) and takeoff flaps is done on the TAKEOFF REF page. The takeoff speeds are calculated by the FMC for nominal conditions (no wind, zero slope and dry runway). The calculated values are validated by selection of the key next to the value or they are changed by entry of other values. The validated or manually entered speeds are sent to the PFD for display on the speed tape. The center of gravity (CG) and gross weight are used to calculate a stabilizer position that is sent to the modular avionics warning electronic assembly (MAWEA) for the green band check. The ACCEL HT is the height where acceleration begins for flap retraction for all engine or engine out operations. The completion status of the preflight sequence shows at the bottom of the page. If the preflight sequence is not complete, a line shows PRE-FLT. Prompts below this line show the CDU page where preflight data is not complete. The order of the prompts are:
- PERF INIT > shows until gross weight or zero fuel weight, reserves, cost index and cruise altitude are entered.
Page Access Access to the takeoff reference page is by TAKEOFF line selection from: - INDEX page - PERF INIT page - RTE page - THRUST LIM page
34.61.0741A-004
- POS INIT > shows until a valid IRS position is entered. - ROUTE > shows until a route is activated.
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TAKEOFF REF Page The function of this page is discussed by the operation of each line: - (1L) FLAP/ACCEL HT shows FLAP/HEIGHT where acceleration begins for flap retraction. Display initially shows prompt boxes for flap setting and a small font default height value. Valid entry or selection shows in large font. Valid flap entries are flaps 10 or 20. Height is entered as height above airport elevation, and valid entries are 400 to 9999.
CLB shows to the right of FLAPS 5 in the diagram. This shows the climb thrust limit mode is armed to engage at the thrust reduction altitude or flap position. This armed climb mode is selected from the thrust limit page and can be CLB, CLB 1 or CLB 2. - (6L) INDEX selects the INIT/REF INDEX page.
34.61.0741B-004
- (2L) E/O ACCEL HT shows the height where acceleration begins for flap retraction for engine out operation. Display initially shows the small font value. Entry shows in large font. Valid entries are 400 to 9999. Deletion puts the default height in small font. - (3L) THR REDUCTION shows the altitude (AGL) or flap position when the thrust limit automatically change from takeoff limit to the selected climb limit. A default value initially shows in small font. Entries have priority over the default value in large font. Deletion of the entered value changes the display to the default value. Entries can be 400 to 9999. The only allowable flap setting is 5 degrees. Entry of 5 in line 3L results in the display of FLAPS 5.
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TAKEOFF REF Page (cont.) - (1R through 3R) V1, VR, V2 show FMC computed values of V1, VR and V2 in small font when valid gross weight (large font), runway identifier, flap input 1L (Takeoff Ref page) and a thrust limit show in 1R of the Thrust Limit page. Line selection of a valid pilot entry into any of these fields (1R through 3R) or selecting 1R through 3R when the scratch pad is empty causes the speed in large font without a caret. - (4R) TRIM CG shows with dashes when no data is entered. Valid entries are whole numbers of CG shown as a percentage of mean aerodynamic cord (MAC). The range of entry is 0 to 40. The FMC also computes the stabilizer position (TRIM). If the calculated TRIM is in the stab trim green band range in the performance data base, TRIM shows in small font. Otherwise, the TRIM field is blank. Also, this display goes blank after takeoff. (5R) POS SHIFT shows the runway and pilot entered distance of the takeoff brake release point from the runway threshold. Entry of the runway shift value is made in hundreds of feet. The FMC calculates the LAT and LON of the brake release point with the entered value. This position is used to update the FMC position of the airplane when the go-around switch is pushed to start the takeoff mode.
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- (6R) THRUST LIM shows when the pre-flight sequence is completed. When pushed, this selects the THRUST LIM page. The header line to this field shows PRE-FLT until all of the pre-flight ranges are complete and then shows dashes. The data line shows prompts to go to the first page. The first page then requires data entry to complete the pre-flight sequence. All data fields are held when the airplane is in the air and are removed at flight completion or by a long-term power interrupt. 34.61.0741C-004
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34.61.0241 -004
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FMCS - APPROACH REFERENCE PAGE
General The approach reference (APPROACH REF) page shows reference data for the approach.
Page Access For access to the page, push the APPROACH prompt from the INDEX page or push the INIT/REF mode key (on the CDU) when a climb mode is not active.
- (6L) INDEX: this key selects the INIT/REF INDEX page. - (1R through 3R) VREF: these lines show the calculated VREF up to three flap settings. These displays are blank unless a valid gross weight is in 1L. The line select in either field when the scratch pad is empty is used to select the flap setting/speed to the scratch pad for entry into 4R. 34.61.0742A-002
APPROACH REF Page The function of the page is discussed by the operation of each line. - (1L) GROSS WT: this line shows the calculated gross weight. If calculated gross weight is not valid, box prompts are shown. - (4L) RUNWAY LENGTH: this line shows the runway length in feet and meters for the origin airport up to 400 nm along the route, or before the halfway point to the destination, whichever is less. It shows the runway for the destination after more than 400 nm or beyond the halfway point, whichever is less.
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APPROACH REF Page (cont.) - (4R) FLAP/SPEED: this field initially shows dashes until data is entered. A speed or flap setting/speed is entered to show which speed is to be used for landing. The speed is also shown on the PFD speed tape. When data is removed from this field, data will also be removed from the speed tape and the field will again show dashes. - (6R) THRUST LIM: this key selects the THRUST LIM page. 34.61.0742B-002
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FMCS - REFERENCE NAVIGATION DATA PAGE
General This page shows additional data about a selected waypoint, navaid, airport, runway or route that resides in the navigation data base. This page can also inhibit the use of specific navaids for position updating and inhibit VOR/DME position updating.
- (3L) MAG VAR or LENGTH: if the identifier in 1L is a navaid, this line shows the magnetic variation of the navaid. If the identifier in 1L is a runway, this line shows the runway length. For other entries in 1L, this line and the header line is blank.
Page Access 34.61.0743A-001
To access the page, push the REF NAV DATA line select key from the INIT/REF INDEX page.
REF NAV Data Page The function of this page is discussed by the operation of each line. - (1L) IDENT: shows dashes initially. Enter a valid waypoint, navaid, airport, or destination runway to show the related information. If the entry is not valid, the message NOT IN DATA BASE shows in the scratch pad. Push the clear key or leave and return to the page to clear the scratch pad message. - (2L) Latitude: this line shows the latitude of a navaid, waypoint, airport, or runway in line 1L.
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REF NAV Data Page (cont.) - (4L/4R) NAVAID INHIBIT: shows dash prompts initially. An entry of a navaid on this line inhibits its use for navigation position updating. Entry of two VORs, VOR/DMEs, VORTACs, or DMEs is possible with these keys. Entry/delete to a line that shows a navaid removes the inhibit of the navaid. Long term power interrupt or flight completion clears all entries. A navaid entry at 4L/4R is not inhibited from manual, route or procedure tune capability. - (5L/5R) VOR ONLY INHIBIT: shows dashes initially. An entry of a navaid on this line inhibits its use for navigation position updating. Entry of up to two VORs is possible using these keys. Entry or a delete to a line that shows a navaid removes the inhibit of the navaid. A long term power interrupt or flight completion clears all entries. A navaid entry at 5L/5R is not inhibited from manual, route or procedure tune capability.
- (3R) ELEVATION: shows elevation of the navaid, airport, or runway threshold in line 1L. For waypoints entries in 1L this field is blank. - (6R) VOR/DME NAV: when the inhibit prompt shows, selection of this key inhibits VOR/DME radio position update and changes the prompt to ENABLE. When the ENABLE prompt shows, ALL shows in 5L and 5R in small font. Entries in this line overwrites the present navaid identifier shown in 5L or 5R. Selection of this key when ENABLE shows, enables VOR/DME update, returns the prompt to INHIBIT and returns 5L and 5R to dash prompts. Status is kept through flight completion and power interrupts. 34.61.0743B-001
- (6L) INDEX: push to return to the INIT/REF index. - (1R) FREQUENCY: if the identifier in line 1L is a navaid this field shows the navaid’s frequency. Otherwise this field is blank. - (2R) LONGITUDE: this line shows the longitude of the navaid, waypoint, airport, or runway threshold in 1L.
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FMCS - MAINTENANCE PAGES
General
Performance Factors
The maintenance pages show maintenance related data that is accessible on the ground through the INIT/REF INDEX page. Selection of the MAINT> prompt causes the MAINTENANCE INDEX page to show. The maintenance pages are: - Navigation data (NAV DATA) crossload page
The performance factors page shows performance data that the maintenance crew can modify due to engineering requirements. The FMC uses this data in its performance calculations. The flight crew can modify some of these parameters on the TAKEOFF REFERENCE page. At the end of the flight the flight crew entries go away and the values found on this page show.
- Performance (PERF) factors page
Functional discussion of this page is in maintenance practices.
- Inertial reference system (IRS) monitor page IRS Monitor Page NAV Data Crossload Page This page is used to transfer the navigation data base of one FMC to the other to save time. This occurs in the normal 28 day update. This page shows automatically at power-up if the FMCs detects a difference in the navigation data bases. Functional discussion of this page is in maintenance practices.
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This page shows an estimate of position error rate for each IRU at the end of each flight. The maintenance crew uses this data to help determine the serviceability of the IRUs. Functional discussion of this page is in maintenance practices.
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FMCS - CLIMB PAGES
General
Page Access
The VNAV mode key on the CDU is used to select climb, cruise and descent performance modes. When the VNAV key is pushed in flight, the page shown is the active performance mode (CLB, CRZ or DES). On the ground, the page shown is the CLB page. To access the other pages, the climb, cruise and descent pages are numbered 1/3, 2/3, and 3/3.
Access the climb page by selection of the VNAV mode key (on the CDU) when CLB is the active performance mode.
Economy Climb Page The function of this page is discussed by the operation of each line.
Three CLB performance modes are available: - Economy (ECON) - Selected Speed (SEL SPD) - Engine Out (ENG OUT) CLB segments may be determined for altitudes only or to show constraints at the waypoints of the flight plan. The default climb has two segments, 250 knot climb to 10,000 feet followed by an economy climb from 10,000 feet to cruise altitude. However, the speed transition altitude and limit speed values change automatically, this occurs when a departure airport is entered that has a stored speed transition altitude that is different than the normal default values. The limit speed value is a minimum speed that uses gross weight.
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- (1L) CRZ ALT: a cruise altitude entry on the PERF INIT page shows on this page. This altitude may be changed. - (2L) ECON SPD or SEL SPD: entry of a speed or mach value results in a change to selected speed (SEL SPD). - (3L) SPD TRANS: this line shows the speed transition altitude stored in the navigation data base for the origin airport. This value can not be modified. 34.61.0745A-001
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Economy Climb Page (cont) - (4L) SPD RESTR: this line allows entry of a speed restriction to an altitude less than the cruise altitude. When the SPD RESTR segment is passed, it is replaced by dashes. - (5L) ECON: this line shows when SEL SPD is on 2L. Selection of this line changes speed in 2L to ECON speed. - (6L) ERASE: this line shows when a vertical or lateral flight plan modification is pending. When this line is selected, all modifications that are pending are erased.
- (5R) ENG OUT: this key selection changes the page display to the ENG OUT mode. - (6R) CLB DIR: this line shows when there is an altitude constraint in the climb part of flight. When selected, all altitude constraints are removed between the current altitude and the MCP altitude. 34.61.0745B-001
- (1R) AT XXXXX: (XXXXX is next constrained waypoint) This line shows speed and altitude constraints, if there are any. They can be removed, but they can not be modified. - (2R) ERROR: this line shows a calculated error at the waypoint in 1R. If the error is predicted to be less than 200 feet low or if the distance error is predicted to be less than 1 nm long, or if no climb waypoint constraints are there, this line is blank. LO resolution is 10 feet. LONG resolution is 1 nm. - (3R) TRANS ALT: at FMC power-up, this value defaults to 18,000 feet. The value may be changed. - (4R) MAX ANGLE: this line shows calculated flaps up max angle climb speed for the present conditions.
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Economy Climb Page (cont) All other climb pages show data that is nearly the same but the data is changed for the type of CLB mode.
Selected Speed Climb Page This page shows when a climb speed (see line 2L above) is selected.
Engine Out Climb Page This page shows when an engine-out climb (see line 5R above) is selected.
Engine Out Selected Speed Climb Page E/O 240KT CLB Page This page shows when an engine-out climb speed is selected. 34.61.0745C-001
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34.61.0245 -001
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FMCS - CRUISE PAGES
General Use the VNAV mode key to select cruise (CRZ) performance modes. Six cruise modes are available: - Economy (ECON) - Selected speed (SEL SPD) - Long range cruise (LRC) - Engine out (E/O) - Cruise climb (CRZ CLB) and - Cruise descent (CRZ DES)
- Selection of the ECON line when selected speed cruise or long range cruise mode is active - Automatic access if the CLB page is shown and a change is made from CLB to CRZ (and ECON was the active CLB mode) - Selection of NEXT PAGE from the CLB page - Selection of PREV PAGE from the DES page
Economy cruise is the normal cruise mode. Push the VNAV mode key to show the active cruise page when the cruise mode is active.
Page Title
The cruise page allows evaluation of trip-fuel burn and time-to-destination for the cruise phase with step climbs or with no step climbs. It also allows change of the cruise altitude or cruise mode when the airplane is in VNAV cruise.
The page title line shows the present active cruise mode. If mode control panel (MCP) speed intervention is selected, the page title changes to ACT MCP SPD CRZ. When guidance controls to a limit speed, the page title changes to ACT LIM SPD CRZ. 34.61.0746A-002
Page Access Access to the CRZ page is by: - Selection of VNAV mode key when the CRZ mode is active
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Economy Cruise Page The function of this page is discussed by the operation of each line. - (1L) CRZ ALT: this line shows the present VNAV CRZ ALT (cruise altitude). This value may be changed. Any change in this value while active in the cruise mode will switch the page format to CRZ CLB or CRZ DES. Also, while active in CRZ with VNAV engaged, an MCP altitude in the altitude window, push the knob to enter the MCP altitude in this field and automatic execution of this modification. - (2L) ECON SPD, SEL SPD or LRC SPD: this line shows the speed target for the cruise phase of flight. SEL SPD may be changed by line selection from the scratch pad.
- (1R) STEP TO: display is an altitude which is different than the CRZ ALT (1L) by a multiple of the step size in 4L. NOTE: This is shown if the top of descent (T/D) is not less than 200 nm. Also this goes blank when TO T/D is shown in line 2R. - (2R) AT: this line shows when a STEP TO altitude is in line 1R. It shows the ETA/distance to the next optimum step climb point. After step climb AT point is passed, and the airplane does not climb to the STEP TO altitude, 2R shows NOW. NONE is shown if no step is requested.
34.61.0746B-002
- (3L) N1: this line shows the target N1 when on an active cruise, cruise climb or cruise descent page. When in active CRZ, the value is the N1 required to maintain the target airspeed at the cruise altitude. - (4L) STEP SIZE: this line shows the entered step size used for step point predictions and step climb predictions. - (6L) ERASE: this line shows only when a vertical or lateral flight plan modification will soon occur. When this is selected, requested modifications are erased.
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Economy Cruise Page (cont) - AVAIL AT: this is the first point after the planned step AT point where a step can be made. That is, if the planned step point occurs before the airplane can climb, because of thrust or buffet limits, the AVAIL AT time and distance shows.
Boeing 747-400 Avionics
Selected Speed Cruise Page This is the page shown when an FMC cruise speed other than ECON cruise speed is selected.
Economy Cruise Climb Page - TO T/D: this shows calculated ETA and distance to go to top of descent (T/D) when within 200 nm.
This is the page shown when the FMC cruise altitude is changed to be higher. That is, the pilot changes line 1L on the ECON CRZ page.
- (3R) DEST FUEL/ETA: this line shows the predicted fuel and estimated time-of-arrival at destination. Economy Cruise Descent Page - OPT: optimum altitude is shown for this line. - (4R) MAX: Present maximum altitude is shown on this line. - (5R) ENG OUT: selection of this line changes page display to engine out LRC CRZ, engine out LRC CRZ DES, engine out LRC CRZ CLB or engine out LRC D/D (drift down). - (6R) LRC: this selection changes speed in 2L to computed LRC speed.
This page is nearly the same as ECON CRZ CLB but the FMC cruise altitude is changed to be lower.
Long Range Cruise Page This page shows the data related to the long-range cruise mode. This page is shown when the LRC line select key is pushed. (see 6R above). 34.61.0746C-002
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Engine Out Cruise Page This page provides for FMC control of the airplane in an engine-out situation.
Engine Out Selected Speed Cruise Page This page is the same as E/O CRZ with a new speed selected.
Engine Out Long Range Cruise Page This page is the same as E/O CRZ with the long-range cruise mode selected. 34.61.0746D-002
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34.61.0246 -002
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FMCS - DESCENT PAGES
General Use the VNAV mode key to select descent performance modes. Two modes are available: economy (ECON DES) and selected speed (SEL SPD DES). These descent modes can be part of a pre-planned route or can be selected. A difference between the descent modes and the climb modes is that all descents are waypoint constrained descents. They have a calculated descent path that is used as a geographically fixed reference path (3D path) for descent guidance. If no descent mode is selected the default descent mode has a two segment descent. The FMC subtracts 10 knots from the transition speed for display and guidance. Therefore, the two-segment descent is: ECON to 10,000 feet followed by a 240 knot selected speed descent to the end of descent (E/D) altitude.
- Selection of the PREV PAGE from the CLB page or NEXT PAGE from the CRZ page when ECON is the DES mode - Automatic access if the CRZ page shows and a change is made from CRZ to DES (and ECON was the active CRZ mode).
Page Title The page title line shows the present or active descent mode. If MCP speed intervention is selected, the page title line changes to ACT MCP SPD DES. When guidance is controlled to a limit speed (such as flap placard), the page title changes to ACT LIM SPD DES. When at the E/D altitude, the page title changes to ACT END OF DES. 34.61.0747A-001
Page Access Access to the descent page is by: - Selection of the VNAV mode key when ECON is the descent mode
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ECON DES Page The function of this page is discussed by the operation of each line. - (1L) E/D AT: this line shows the lowest altitude constraint at a waypoint. If there is no constraint, the page is blank with DES as title. - (2L) ECON SPD (SEL SPD): in ECON mode, command speed is a computed value. Entry of a speed or mach results in a mode change to SEL SPD DES at the entered value.
- OFFPATH DES: this line shows when the necessary data has been entered to allow VNAV flight (gross weight cost index and cruise altitude have been entered). With an active flight plan, OFFPATH DES is shown only when ERASE is not shown. Selection shows the OFFPATH DES page. - (1R) AT: when a speed/altitude constraint has been entered on a LEGS page, the first related waypoint is shown in this field. 34.61.0747B-001
- (3L) SPD TRANS: this line shows the speed transition altitude in the navigation data base for the destination airport less 10 knots to make sure the airplane does not go faster than speed limit. If there is a change to the SPD TRANS segment, the field goes blank and the constraint speed moves to line 2L. - (4L) SPD RESTR: this line allows entry of a speed restriction at an altitude higher than E/D altitude (CAS only). If there is a change this segment, the data is replaced by dash prompts and the constraint speed moves to line 2L. - (5L) ECON: this line shows only when the selected speed mode is in line 2L. Selection changes display in 2L to ECON. - (6L) ERASE: this line shows only when a vertical or lateral flight plan modification might occur. if this is selected, all modifications about to occur are erased.
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ECON DES Page (cont) - (5R) FORECAST: this line shows the descent forecasts page.
DESCENT FORECASTS Page
- (6R) DES DIR: this line is shown when descent is active and there is an altitude constraint between present altitude and the E/ D. Line selection causes all constraints to be removed between present altitude and MCP altitude. If the MCP altitude is lower than the E/D altitude, the E/D altitude is not changed.
This page allows the operator to enter forecast values of some specified parameters to more accurately define the computed descent profile. Data includes wind speed and direction, and altitude when thermal anti-ice starts.
- DES NOW: this is shown on the descent page when it is not active. The DES NOW function causes the system to provide guidance at a 1,250 feet per minute descent rate to the intersection of the vertical profile.
End of Descent
Other descent pages show data nearly the same but the data is changed for the type of DES mode. Selected Speed Descent Page
This page provides a means to change the end of descent. Page access is: - Push the V-NAV mode key when at the end of descent altitude
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This page is shown when a selected speed descent is selected (See line 2L above).
OFFPATH DES Page This page allows data to be shown that is related to a normal descent or a speed brake descent to a defined point.
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End of Descent (cont) - Push PREV PAGE (from the CLB page) or NEXT PAGE (from the CRZ page) when at the end of descent altitude. 34.61.0747D-001
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FMCS - PROGRESS PAGES
General The PROGRESS page shows data on the progress of the flight. The pages show present dynamic flight data.
- (4L) DEST: data (DTG, ETA and fuel remaining) about the destination shows in this line. An alternate destination may be entered to replace the destination waypoint.
Page Access
- DIR TO ALTERNATE: this shows when an alternate waypoint has been entered which is not in the active flight plan.
Push the PROG mode select key to access the PROGRESS page.
PROGRESS Page 1 The function of the page is discussed by the operation of each line. The company flight number from RTE page 1 is shown in the title block on this page. - (1L) LAST/ALT/ATA/FUEL: this line shows waypoint identification altitude, actual time of arrival (ATA) and fuel remaining at the last waypoint that was passed.
- EN ROUTE WPT: this shows when an alternate waypoint is entered which is in the active flight plan. If both CDUs leave this page, this deletes the alternate destination waypoint. - (5L) LRC SPD, ECON SPD, SEL SPD; this line shows when the data in 5L agrees with the appropriate performance mode. LIM SPD: this shows when the airplane performance is limited. MCP SPD: this shows when speed intervention is active. 34.61.0748A-001
- (2L) TO/DTG/ETA: this line shows waypoint identification, distance to go (DTG), estimated time of arrival (ETA) and fuel remaining for the active waypoint. - (3L) NEXT: same as 2L but for the next waypoint.
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PROGRESS Page 1 (cont) - E/O SPD: this is shown when the engine out minimum drag speed mode is active. - (5R) TO: this line shows ETA and distance-to-go to. - TOP of climb (T/C) when CLB mode is active.
- (3C and 4L through 4R) FUEL USED: The total fuel used on line 3C and fuel used on each engine is shown on lines 4L through 4R. If the fuel flow is invalid for more than 2 minutes after engine start, or is invalid while on the ground, the displays go blank. FUEL USED values stay through flight completion and are removed at engine start or long term power down.
- STEP CLIMB when in CRZ mode - Top of descent (T/D) when in CRZ mode and within 200 nm. - End of descent (E/D) when in DES mode. - LEVEL AT when in the drift down (D/D) mode.
- (5L): this line is blank unless there is a 9,000 pound (4091 kilogram) difference between the fuel totalizer and the calculated fuel value. The data fields are as shown when a difference occurs for greater than five (5) minutes. Selection of this prompt causes the system to use the fuel totalizer value and inhibits the calculation of fuel used. Line 6R (CALCULATED fuel) goes blank if 5L is selected.
PROGRESS Page 2 34.61.0748B-001
- (1L) WIND: this line contains wind data. The wind bearing data is the direction the wind is from in degrees true. - (2L) XTK ERROR: this line shows present cross track error. - (3L) TAS: this line shows the present true airspeed.
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PROGRESS Page 2 (cont) - (6L and 6R) TOTALIZER/CALCULATED: the fuel totalizer system value is shown in 6L. The CALCULATED value in 6R is set equal to the TOTALIZER value before engine start. The FMC normally uses the calculated value for its performance calculations. If the fuel flow data is invalid for more than 2 minutes after engine start, the CALCULATED fuel quantity in 6R goes blank the same as the FUEL USED display. The FMC uses the TOTALIZER value for its performance calculations. - (2R) VTK ERROR: this line shows the present vertical track error for a path descent. - (5R): this is the same as 5L but selection causes the system to use the calculated fuel and inhibits the totalizer input. 34.61.0748C-001
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FMCS - HOLD PAGES
General The HOLD AT page allows selection of the present airplane position or any other waypoint for the holding pattern. The HOLD also page allows for selection of details of the holding pattern.
- (6L) HOLD AT: any valid waypoint (1L through 5L) can be transferred to line 6L. A HOLD AT leg is then made after that waypoint. The display then goes to the MOD RTE HOLD page.
Page Access
- (6R) PPOS: this key selection makes a holding pattern with the fix at the present position at the time EXEC is pushed.
To access the HOLD AT page push the HOLD mode select key when there is no other holding pattern, or select NEXT HOLD on the ACT RTE 1 HOLD page.
HOLD Page - (1L) FIX: this line shows the holding fix position.
The HOLD page is shown automatically when a valid holding fix has been entered in the HOLD AT RTE LEGS page. Or push the HOLD mode key after a holding fix has been entered in the route.
- (2L) QUAD/RADIAL: this line allows entry of a specific holding quadrant and radial, if desired. 34.61.0749A-001
HOLD AT Page The function of this page is discussed by the operation of each line. - (1L/R through 5L/R) this is the same as the lines on the RTE LEGS page.
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HOLD Page (cont) - (3L) INBD CRS/DIR: this line shows inbound course and turn direction for a holding pattern. Default is right (R) turn pattern, but the turn direction may be changed when L is entered. - (4L) LEG TIME: the leg time may be changed. The default values are 1.5 minutes above 14,000 feet, or 1.0 minute at or below 14,000 feet. - (5L) LEG DIST: this field will normally show dashes unless a keyboard entry is made. If a LEG DIST entry is made, the LEG TIME field shows dashes. - (6L) NEXT HOLD: this key selection makes prompts for a new holding fix. - ERASE: this is shown only on the MOD HOLD Page. If this is selected, modifications about to occur are deleted.
- (3R) EFC TIME: this line shows a keyboard entry of the time at which further clearance will occur. - (4R) HOLD AVAIL: this line shows the holding time available before exit is required to be at the destination with required reserves. - (5R) BEST SPEED: this line shows the best holding speed for the present altitude. - (6R) EXIT HOLD: this key selection replaces EXIT HOLD with EXIT ARMED and turns on the EXEC light. Push EXEC to activate flight back to the FIX and continue the flight on the active route. EXIT HOLD shows when a HOLD is active. 34.61.0749B-001
- (1R) SPD/TGT ALT: the speed/altitude shown will be the same as that shown on the RTE LEGS page for the HOLD AT leg. This changes to the best speed for the target altitude. - (2R) FIX ETA: this line shows the next time the fix will be passed.
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FMCS - ROUTE LEGS, ROUTE DATA AND WIND PAGES
General The route legs (RTE LEGS) page allows details of each leg of the route to be entered and shown. The route data (RTE DATA) page provides a display of more leg data and an access to the waypoint wind page. The WINDS page allows a look at future winds. It also shows temperatures at specified altitudes to be entered for up to 120 waypoints.
Access to the RTE DATA page is by selection of RTE DATA from RTE LEGS page or waypoint WINDS page. Access to the WINDS page is by selection of prompt from RTE DATA page. RTE LEGS Page
Page Access
The function of this page is discussed by the operation of each line.
Access to the LEGS page is by:
Leg directions: the line shows the calculated course or heading to a waypoint. It also shows specified procedural instructions from the data base such as:
- LEGS mode key selection - RTE 1 LEGS line selection on RTE 2 LEGS page
- HOLD AT - PROCTURN
- Legs line selection on RTE 1 data page. - Automatic access from WINDS or RTE DATA pages on flight completion.
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- Automatic access when alternate route is activated on offside CDU.
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NOTE: For heading or track legs, HDG or TRK follows the displayed value. Courses and headings are relative to magnetic north between 73°N and 60°S latitude, otherwise true north. The value is also relative to true north when the HDG REF switch is set to true. Only values relative to true north are followed by the letter T (for example, 222°T or 137°TTRK). - (1L through 5L) Waypoint identifier; valid entries are: waypoints, airports, navaids, runways for destination airport, waypoints selected on the ARRIVAL page, latitude/longitude. If a destination runway is entered before the last waypoint of the flight plan, all waypoints after the runway are removed. - (6L) RTE 2 LEGS: this line is shown on all pages but not MOD pages. Selection shows RTE 2 LEGS page.
Boeing 747-400 Avionics page has a MAP CTR STEP prompt. It replaces the RTE DATA prompt and a CTR symbol shows next to one of the waypoints. This waypoint will be the same waypoint that is centered on the navigation display (NC)
The CTR symbol can be moved to the next waypoint by line select of the MAP CTR STEP prompt. Continued selection of the MAP CTR STEP key causes the CTR symbol to move down the page through the entire route. - ACTIVATE: this is shown only on non-active RTE LEGS pages when not in PLN mode.
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- ERASE: this is shown only on MOD pages. Selection will remove all LEGS modifications. - (1R through 5R) Speeds/Altitudes: speeds and altitudes may be entered on these lines. - (6R) RTE DATA: this line is shown only on active or modified RTE LEGS pages and when not in PLN mode (on EFIS control panel). Line selection shows the RTE DATA page. - MAP CTR STEP: this is shown only if the PLN mode (on EFIS control panel). When PLN mode has been selected, the LEGS
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RTE DATA Page - (1L through 5L) ETA WPT FUEL: this line shows the estimated time of arrival and estimated fuel at the specified waypoint. ETA and estimated fuel calculations are for a direct flight across route discontinuities. - (6L) ERASE: this is shown on all MOD pages. Selection removes all route modifications. - (1R through 5R) WIND: selection will show the waypoint WINDS page for that waypoint. The W> prompt shows that future winds have been entered at that waypoint.
- (5R) ALT/OAT: dash prompts are shown unless the offside CDU has ALT/OAT entries and also shows the WINDS page. Entry of an OAT at an altitude will be shown in 5R and results in a change of the OATs in lines 1L through 4L. OAT entries are in degrees centigrade. - (6R) RTE DATA: select this key to show the RTE DATA page.
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- (6R) LEGS: selection shows the RTE LEGS page.
WINDS Page - (1L through 4L) ALT OAT: these lines show waypoint wind altitudes and temperatures. Dashes are shown if less than 4 altitudes have been entered. - (1R through 4R) DIR/SPD: these lines show the wind speed and direction.
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FMCS - FIX PAGE
General The fix page allows the waypoints to be made from the intersection of the present flight plan and selected radials and distances from known waypoints. These fixes are shown on the navigation display (ND).
Page Access Push the Fix mode key to access this page.
FIX Page The function of this page is discussed by the operation of each line. - Azimuth data: azimuth data is related to magnetic north when the airplane is between 73°N and 60°S latitude. Otherwise, it is relative to true north. The data is also related to true north when the HDG REF switch is set to TRUE. - (1L) FIX/SELECTED REFERENCE POINT or waypoint identifiers in the data base may be entered on this line:
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- Airport - Navigation Aid - Waypoint - Radial and distance from a point - Latitude/longitude These entries may be made through the keyboard or with line selection from another page. Entry of a fix shows on the ND with a green circle around the appropriate symbol. The bearing and distance from that fix also shows. - (2L through 4L) BRG/DIS: valid entries are bearing or distance from the FIX. If an intersection of the radial line or distance circle with the active flight plan is there, the ETA and estimated altitude at the intersection shows. Entry of a bearing causes the ND to show the selected radial(s) as dashed (--) green lines, that extend for 700 nm from the selected reference point (fix). Along each radial, the radial angle for magnetic north shows with the letter R before it. 34.61.0751A-001
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FIX Page (cont) Entry of a distance causes the ND to show the selected distance as a dashed green circle around the selected reference point (fix). The radius of the circle is equal to the selected distance. Along the circle, when in view, the distance value shows in green numbers. A distance is valid, and shows, if it crosses the flight plan.
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- (5L) ABEAM (nearest point abeam): selection results in the display of the bearing and distance from the FIX to the nearest intersection on the flight plan path, also shown is the distance along the flight plan to the nearest abeam point plus the ETA and altitude at that point. - (6L) ERASE FIX: this selection causes all FIX data for that page to be removed from the CDU display. NOTE: NEXT PAGE allows selection of three radials and/or distances and a point abeam from a second fix point and a second ETA-ALT entry.
- (6R) ETA/ALT: valid entries are altitude, flight level or time. Time entry must be followed by a Z to show the difference between altitude, flight level and time. Entry of an altitude/flight level or time results in the display of the airplane’s future positions along the active route at that altitude or time on the ND.
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FMCS - NAVIGATION RADIO PAGE
General The NAV RADIO page is used to manually tune the radios, delete entries and to preselect data for future use.
Mode entry: enter a frequency or identifier in the scratchpad then select the L and/or R VOR fields to enter the manual tune mode. The autotune mode shows when there is no M, R or P tune mode(s) present.
Page Access To show the NAV RADIO page, select the NAV RAD mode key when one or more FMCs are operable.
- (2L) CRS/RADIAL: the airplane’s radial shows on line 2L. If the VOR on line 1L is manual course may be entered on line 2L. If this is done when the map mode shows on the navigation display (ND) the FMC sends coordinates of the selected course as a great circle radial line to the ND.
NAV RADIO Page The functions of this page is discussed by the operation of each line key. - (1L) VOR L: data on this line is frequency, tune mode identifier and VOR identification. The tune modes are manual (M), procedure (P), route (R) and autotune (A). When the FMC tunes a DME with no colocated VOR station, the DME identifier shows in the data field at line 1L.
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The ND then shows the selected VOR course as green lines on the map. The selected course and radials extend in both directions for 700 nm from the not autotuned navaid. The selected course and reciprocal course show along the course radial in green numbers. 34.61.0752A-002
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NAV RADIO Page (cont) - (3L) ADF L: data on this line is ADF station frequency and tune mode. Station frequency is manual entry only. There are three modes: ADF, BFO and ANT. The default mode is ADF. To change a mode enter the first letter of the mode in the scratch pad and select the ADF line. To cancel a mode select the DEL key in the scratch pad and enter this on the ADF line. The ADF mode does not show, in this case. - (4L) ILS: data on this line is ILS frequency/course and/or PARK or frequency/course (A) auto or (M) manual annunciations.
The frequency and course show as small numbers followed by PARK when the airplane is less than 200 miles from top-of-descent, or past the active route halfway point.This ocurrs when the runway is ILS equipped and in autotune. Before this PARK shows only. PARK is removed and the frequency and course (A) display are in large letters when 50 nm from top of descent or within 200 nm direct distance to the runway threshold or when active in descent. To enter ILS data manually, enter the ILS frequency/course in the scratch pad and select the ILS line key. Manual entry of a course is not allowed when autotune is active. 34.61.0752B-002
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FMCS - IRS LEGS AND IRS PROGRESS PAGES
General Airplane navigation is usually done by the FMCs. If the FMCs fail, the CDUs provide some navigation capability. During normal operations, FMC route data is sent to and stored in the CDUs. If the FMC fails, the CDU uses IRS data to update the FMC route data. When the selected FMC input to the CDU has failed and the LEGS or PROGRESS mode key is pushed, the IRS LEGS or IRS PROGRESS page is shown. The IRS LEGS page allows details of each leg of the route to be entered and shown. The IRS PROGRESS page shows data about the progress of the flight.
Page Access To show the IRS LEGS page or IRS PROGRESS page, push the LEGS or PROG mode key when the FMC selected by the CDU is failed.IRS LEGS Page
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The function of the page is discussed by the operation of each line. - Leg Directions: this shows the computed course to waypoint. For the first waypoint, the course is related to the present selected reference, magnetic north or true north. For the other waypoints, the course is referenced to true north. Values relative to true north are followed by the letter T. Values relative to magnetic north are followed by the letter M. - (1L through 5L) Waypoint Identifier: valid entries on these lines are waypoint identifiers. The latitude/longitude of these waypoints shows to the nearest 0.1 minute. - (6L) ERASE: this line shows only on MOD pages. Its selection removes all MOD data. - (1R through 5R) Latitude/longitude: the CDU shows latitude/ longitude for each waypoint on these lines.
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IRS PROGRESS Page The IRS progress page shows present dynamic flight data. Usually, no entries or selections are possible, but on line 4L they are possible.
- (6C) DTK: this line shows the desired track angle related to the magnetic or true reference, and it is followed by an M or T. - (5R) GS: this line shows present ground speed.
- (1L) LAST: this line shows the waypoint identifier and altitude of the last waypoint passed.
- (6R) TK: this line shows the present track angle related to the magnetic or true reference and is followed by an M or T.
- (2L and 2R) TO DTG and TTG: this line shows distance-to-go and time-to-go to the next waypoint. 34.61.0753B-001
- (3L and 3R) NEXT: these lines show waypoint identification, distance-to-go (DTG) and time-to-go (TTG) from the present position along the route. - (4L and 4R) DESTINATION: usually, this line shows DTG and TTG for the destination. However, a different latitude/longitude or other flight plan waypoints may be entered. If this is done, data is shown for the airplane to go to that waypoint. The header shows DIR TO ALTERNATE if the waypoint entry is not in the active flight plan. The header shows ENROUTE WPT if the waypoint entry is part of the active flight plan. The DELETE function is used to remove the waypoint entry. - (5L) IRS: this line shows the present position based on the IRS with a specific source (L, C or R). - (6L) XTK ERROR: this line shows the present crosstrack error.
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FMCS - ALTERNATE NAVIGATION RADIO PAGE
General The ALTN NAV RADIO page provides an alternate way to tune the navigation radios.
- (3L) ADF: this line shows the manually entered ADF frequency. BFO or ANT follows the frequency if the ADF is in one of those modes. If the ADF is in the ADF mode, no letters follow the frequency. This function is blank on the center CDU.
Page Access To show the ALTN NAV RADIO page, push the NAV RAD mode key when both FMCs have failed and airplane on ground or when airborne and the master FMC is failed.
- (4L) ILS: this line shows the manually entered ILS frequency and the course, with a / in between. If no frequency has been entered, PARK is shown. - (6L and 6R) PRESELECT: this line is an easy-access storage for data to be entered later in lines 1L through 4L.
ALTN NAV RADIO Page 34.61.0754 -001
The function of the page is discussed by the operation of each line. - (1L) VOR: this line contains the manually entered VOR frequency. The letter M follows the frequency; this shows the frequency is manually tuned. However, this function is blank on the center CDU. - (2L) CRS: this line shows the manually entered course for the VOR in line 1L. Dashes are shown if no course has been entered, or if it has been manually deleted. This function is blank on the center CDU.
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FMCS - FUNCTIONAL BLOCK DIAGRAM
General
Input/Output Function
The FMCS performs many functions to reduce crew workload and improve airplane economy. The FMCS does this by processing information received through the airplane and flight crew interfaces. The processing done by the FMC is divided into the following eight functional blocks:
The FMCS gets flight crew information from the CDU and airplane information from discrete and ARINC digital interfaces. The information is first checked for presence and validity and then stored for use by the other functional blocks of the FMC. The input/output function also sends data to other systems. ARINC digital and discrete interfaces allow the FMC to present information to the flight crew and to control other airplane systems.
- Input/output - Navigation and radio tune - Performance - Guidance - Thrust management - EFIS map display - Data base storage - BITE The processing done by the CDU is divided into these four functional blocks: - EFIS map display - Alternate navigation - Alternate radio tune - ARINC 739 interface
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Navigation/Radio Tune Function Airplane position and velocity data are determined by the navigation function. Position and velocity data comes from the inertial reference system. Radio position data comes from the VOR and DME. The navigation function also computes other parameters required for lateral guidance using NAV data base and sensor data. Navigation radios are normally auto-tuned by the master FMC. Manual tuning is done through the CDU NAV radio page. 34.61.0756A-002
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Performance Function The vertical profile of the airplane’s flight is computed by the performance function. Using initialization and sensor data and information stored in the performance data base, predictions of airplane performance are done. The vertical profile is computed to produce the optimum trajectory for economical operation, but can be changed through flight crew inputs.
The autothrottle drives the thrust levers with the autothrottle servomotor generator in response to commands from the guidance function. The autothrottle also has dedicated modes which are selected on the AFCS MCP. The thrust limit function computes maximum thrust and thrust limit mode for display and control. The engine trim function equalizes thrust of all engines to eliminate throttle stagger.
Guidance Function EFIS Function The outputs required to control the airplane along the lateral and vertical paths computed by the navigation and performance functions are computed by the guidance function. The lateral flight plan consists of a string of waypoints from origin to destination airport. The vertical profile is defined by a string of performance legs which contain the control parameter of either path or speed. Each performance leg also defines a means of control of either path or speed on elevator. Speed commands go to the thrust management function when the path on elevator function is active. Thrust Management Function
The navigation display map modes are used to monitor aircraft progress along the flight plan. Vertical profile points along the route are also displayed. Map data selector switches on the EFIS control panel add or remove information from the display.
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The thrust management function performs these three functions: - Autothrottle - Thrust limit - Engine trim
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Data Base Storage Data bases are stored in the FMC to supply information to the various functional blocks. There are three types of stored data: - NAV data base - Performance data base - Operation program The Navigation data base contains: - Navaid data - Waypoints and ground reference points - Airways - Airports/runways/gates - Procedures (SIDS, STARS and approaches) - Company routes
operation and interfaces. The FMC stores the BITE data in a non-volatile memory which can be transferred to the data loader or read during shop repair.
Alternate Navigation/Radio Tune The CDU can do lateral navigation if no FMCs are operational. The lateral flight plan is stored and updated in CDU memory. The onside IRU is used to compute airplane position and velocity. The CDU can also produce a map display to monitor airplane progress along the flight plan. The CDU can tune the onside navigation radios if no FMCs are operational.
The performance data base contains: ARINC 739 Interface - Engine model data - Aerodynamic model data - Aircraft characteristics - Speed/altitude data
The CDU is used as a crew interface for other airplane systems. A system is selected from the CDU menu page. 34.61.0756C-002
The operational program defines the order of operations and calculations to run in the various functional blocks. BITE Function Hardware and software monitors are used to detect faults in FMC
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FMCS - NAVIGATION FUNCTION
General The navigation function of the FMC calculates airplane position, velocity data and navigation data for the guidance and performance functions and for display.
the resulting range rings gives two possible locations for airplane position. The FMC decides which location to use by IRS position data. The result is DME/DME latitude and longitude.
Position Calculation
VOR/DME Position Calculation
The FMCs use the three calculations of position in this priority:
Airplane position is calculated from the bearing and range provided by the VOR and DME data.
- LOCALIZER - DME/DME/IRS - VOR/DME/IRS - IRS only
Localizer Position Update If valid localizer data is available, the FMCs uses localizer beam deviation to correct airplane position normal to the approach path.
IRU Position Average and Rejection If all three IRU inputs are valid, the FMC computes IRU position as the weighted average of all three inputs. If a single IRU position is different from the average position by more than 30 nm for over five seconds, the data from that IRU is not used for the rest of the flight. If only two IRUs are available, each FMC uses data from one IRU. FMC-L uses the left or center IRU and the FMC-R uses the center or right IRU.
DME/DME Position Calculation Slant range is changed to ground range and the intersections of
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IRU Position Average and Rejection (cont) If the two IRU positions have a difference that exceed a variable comparison threshold, a CDU message, VERIFY POSITION shows. If only one IRU is available for navigation, both FMCs use its data for position and velocity.
FMC selects a single IRU input from the remaining two in an onside then center priority. If there is a difference between FMC position and single IRU position at the beginning of polar navigation, the FMC slowly changes to the IRU position.
Altitude IRU Velocity Average and Rejection The altitude calculation is a combination of inertial data and ADC. Average of the three north and east velocity components from the IRUs is used to compute the FMC north and east velocity for the FMC velocity vector. If three IRUs are available for velocity data, an individual IRU’s north and east velocity components are looked at in addition to the average velocity components.
34.61.0757B-001
DME/DME radio updates go to the total velocity vector calculation to correct the average north and east velocity signals. This improves the total velocity vector output.If a single IRU velocity is different from the average velocity by more than 20 knots for five seconds, the data from that IRU is not used for the rest of the flight.
Polar Navigation Polar navigation begins when the FMCs position reaches a latitude greater than 84 degrees. At this point the 3 IRU positions are cross-compared and the one that is farthest away is rejected. Each
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FMCS - NAVIGATION RADIO TUNING
General
DME Tuning
The master FMC sends tuning frequencies to the navigation radios. The frequencies are determined automatically by the FMC or manually through the CDU entries on the nav radio page. The navigation radios send bearing and distance data back to the FMC. The FMC computes airplane position using radio and inertial data.
The DME sends slant range distances to the FMC. The FMC corrects the slant range using airplane altitude. The DME is a scanning type which can provide distance to multiple stations. The FMC controls the DME’s foreground list of five channels. Channels one and two are always in an autoselection mode of the pair of navaids selected by the FMC calculations of best geometry. Channels three and four are directed to the next best pair or a procedure, manual, or route tuned station. Channel five contains the ILS DME station.
Tuning Methods The following are the four ways the VOR and DME are tuned by the FMCS: - Manual tuning occurs when an entry is made on the CDU. - Procedure tuning occurs when a navaid is specified in the active departure or arrival procedure. - Route tuning occurs when a VOR station is the next or last waypoint in the active route and within 250 nm.
Navaids are first selected using the nav data base. The data base is searched to find the navaids within the maximum EFIS map display range. This list of navaids is then sorted for navaids which meet certain criteria and geometry. This candidates list then has navaids selected from it which are validated by the background scan of fifteen stations done by the DME. 34.61.0758A-002
- Autotuning occurs as described in the following paragraphs.
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VOR Tuning When any tuning method other than autotune is active (manual, procedure, or route tuning), the VOR receivers are tuned to the indicated station. When autotune is active, the VOR receivers are tuned to the stations determined to be the best for radio position calculation.
34.61.0758B-002
ILS Tuning The ILS receivers are normally tuned automatically by the master FMC. This is done prior to the approach when certain criteria are met. The ILS receivers can also be tuned through inputs on the CDU. When no manual or automatic selection is made, the FMC parks the ILS receivers.
ADF Tuning The ADF receivers are manually tuned through inputs on the CDU. Error Term The FMC computes an estimate of position error, or Error Term (ET). ET is adjusted to reflect the uncertainty in FMC position based on expected errors of the sensor(s) which are updating the FMC position. The radio position updates must fall within the ET to be used. The ET can be as small as 1 NM or as large as 30 NM.
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FMCS - PERFORMANCE FUNCTION
General Performance management is the FMCS function that optimizes the airplane’s vertical profile. The FMC’s performance function provides optimal values for speed and thrust. It also provides the most economical flight path profile. These values are calculated with: - Fuel/weight
and EICAS message: FUEL QTY ERROR-PROG PG 2 (CDU) and FMC message (MAIN EICAS). It shows when the calculated fuel remaining is different from the fuel quantity system (FQS) by 9,000 pounds for five minutes. A valid calculation of gross weight is required for all other performance calculations.
- Speed envelope and optimum speed - Flight plan trajectory - Maximum altitude and optimum altitude - Thrust target - Takeoff speeds and stab trim
During preflight, either zero fuel weight (ZFW) or gross weight should be entered on the PERF INIT page (or the weight and balance computer gross weight should be validated on the PERF INIT page). ZFW and gross weight can be entered or updated in flight. All performance calculations will be inhibited until this entry is made. 34.61.0759A-001
- Approach reference speeds lookup tables
Fuel/Weight Calculation This function calculates airplane gross weight, fuel burnoff and fuel remaining. It also sends a fuel quantity alert. This alert is a CDU
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Speed Envelope and Optimum Speed Calculations
Flight Plan Trajectory Calculation
The speed envelope function calculates the minimum and maximum operating speeds for any altitude, weight and configuration inputs (such as flap position, maneuver load factor, gear position).
The trajectory prediction function uses equations of motion, along with models of the airplane and engine characteristics, to simulate the flight of the airplane over the planned trajectory. This trajectory optimizes the time the airplane is in an idle engine configuration. It still must observe altitude and speed restrictions.
The FMC calculates optimum VNAV speed targets. The calculation mixes altitude, pressure, cost index, gross weight, wind and temperature to minimize airplane operating cost. The optimum VNAV speed targets are: - Minimum transition climb - Economy climb - Economy cruise - Economy descent - Maximum angle climb - Long range cruise - Engine out long range cruise - Engine out minimum drag - Best hold The FMC invalidates all speed targets and removes calculated speeds from all CDU pages when any of the performance targets become invalid during flight.
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The simulation provides data about the predicted path of the airplane to the guidance function, CDU display and EFIS display. It also provides data for scheduling the cabin pressure control system (CPCS). The flight path prediction function uses: - Gross weight - Cost index - Cruise altitude - Destination airport - At least one waypoint - Latitude and longitude - Active lateral and vertical guidance - Altitude
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Flight Plan Trajectory Calculation (cont) - Fuel quantity - Lateral path with two or more waypoints - End of descent (E/D) point In addition to these, there are several optional inputs which increase the accuracy of the flight path prediction. They are: - Wind at altitude at each waypoint and temperature forecasts - Icing conditions forecast for the descent
If full trajectory data is not there, the prediction capability is reduced to those items on the CDU PROG page (but not descent data).
Maximum and Optimum Altitude Calculation Maximum altitude is the altitude the airplane can climb so the planned climb speed and the selected cruise speed are in the speed envelope. This shows on the CRZ page. If the entered cruise altitude is equal to or more than the maximum altitude, the fuel predictions do not show. This is done to prevent bad predictions.
- Fuel flow factor - Climb thrust derate
Optimum cruise altitude is calculated for the selected cruise mode and the flight plan distance.
- Drag factor 34.61.0759C-001
When all of the above are present, the flight path prediction function calculates the flight trajectory from takeoff to landing. If descent path data is not there, the predicted flight trajectory will not include a descent path for guidance, or a valid top of descent (T/D) for display on the ND. Also, waypoint predictions to the end of the flight plan will not show a descent. In fact, all waypoints past the top of climb (T/C) show a continuation of the cruise.
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Takeoff Speeds and Stab Trim Calculation 34.61.0759D-001
This function calculates advisory takeoff speeds (V1, VR and V2) and takeoff stabilizer position equal to those found in a quick reference handbook (QRH). The data for this function is in the performance data base. The advisory stabilizer position is calculated with the entered gross weight and center of gravity in addition to thrust rating.
Thrust Target Calculation This function calculates two thrust targets: - A cruise target thrust. This value is a reference value to set an approximate thrust value when the airplane is at the planned cruise altitude with the autothrottle disengaged. - A target for the thrust management function to set the throttles when the speed in level flight mode is reached.
Approach Reference Speeds Calculation This function takes the approach speeds (Vref) from the performance data base (PDB) for gross weight and flap positions. It also provides these values to the CDU for display on the INIT/REF APPROACH page.
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FMCS - GUIDANCE FUNCTION
General
Vertical Navigation
The guidance function receives inputs from the CDU, performance and navigation functions and MCP. The guidance function processes these inputs and sends commands to the:
The FMC calculates vertical guidance with initial inputs as the vertical flight plan and compares that to the present vertical position. The guidance function sends vertical steering (VNAV) commands to the AFDS and thrust and speed commands to the autothrottle function for vertical control of the airplane. The FMC calculates four basic VNAV modes:
- Autopilot flight director system (AFDS) for lateral and vertical flight control
Guidance Position
- The VNAV Speed/Thrust causes the autopilot elevators to control to the FMC speed and the throttles to control to a thrust value. This occurs in climb, to initiate an early descent or during an engine out driftdown.
With data from the navigation and performance blocks and inputs from the CDU and MCP, the FMC calculates lateral and vertical guidance of the airplane.
- The VNAV Path/Speed mode commands vertical path (altitude) on elevators and airspeed on throttles. This mode is used during cruise and shallow path descents.
- Thrust management block for autothrottle servo control
34.61.0760A-001
Lateral Navigation The FMC calculates lateral guidance for the paths between waypoint and curved transitions between each path segment. The guidance function looks at the route, desired and airplane position to calculate lateral guidance (LNAV) commands. These go to the AFDS.
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Vertical Navigation (cont) - The VNAV Path/Idle commands a descent path on elevators and throttles to the idle position. This is the basic descent mode. - The VNAV Speed/HOLD mode commands airspeed on elevators and the throttles to hold (this removes servo power from the servomotor). This allows manual throttle control. This mode is used in step descents. 34.61.0760B-001
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FMCS - LNAV ENGAGE REQUIREMENTS
Engage Initiation LNAV starts by a push of the LNAV button on the AFCS mode control panel (MCP). The MCP sends the LNAV request to the flight control computer (FCC).
- The airplane will make a smooth change to the active leg with a maximum bank angle of 25 degrees
FMC Response FCC/MCP Response When the FCC gets the LNAV request, the FCC determines if the transition to LNAV operations is allowed. If LNAV is possible, the LNAV arm signal goes to the MCP and to the PFD. Indication of LNAV arm is the primary flight display (PFD) flight mode annunciator (FMA) shows LNAV in white, the LNAV light on the MCP comes on and a signal called LNAV ARM goes to the FMC.
LNAV Engage Criteria If the airplane is within 2.5 NM of the desired active flight plan leg when LNAV is requested, the FMC captures LNAV. If the airplane is more than 2.5 NM from the active leg when LNAV is requested, the FMC captures when:
When the FMC gets the LNAV ARM signal from the AFCS MCP, and the requirements shown on the graphic are met, the sign status matrix (SSM) of the lateral commands from the FMC change from NCD to valid.
FCC Action The FMC lateral commands go to the FCC. When the FCC detects that the SSM has changed to valid, LNAV changes from armed to engaged. The FCC uses the commands to produce the roll commands for flight director display and/or for control of the lateral control servos. Indication of LNAV engaged is the FMA shows LNAV in green. A signal called LNAV OPERATE goes to the MCP to keep the mode engaged.
- The airplane track will intercept the active leg and, 34.61.0761 -001
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FMCS - VNAV ENGAGE REQUIREMENTS
The engage requirements for VNAV are nearly the same as those of LNAV but for those shown. It should be noted that the FMC requirements are different and that the FMC has another output to the autothrottle servo. 34.61.0762 -001
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FMCS - SPEED AND ALTITUDE INTERVENTION
Speed Intervention
Altitude Constraint Deletion
When in VNAV operation, the FMC calculates the target airspeed for display on the PFD speed tape and for VNAV commands. For this reason, the speed display on the AFCS MCP is normally blank in VNAV. An easy way to manually change the target airspeed is to use the speed intervention function. Push the speed select knob on the MCP. A switch behind the knob sends a discrete to the FMC. The speed display unblanks and shows the present FMC target speed. This value may now be changed. The FMC uses the speed selected on the MCP display as the target instead of its calculated value. Push the speed select knob again to return the FMC to normal operation.
In VNAV climb (or descent) and with the MCP altitude set above (below) a constraint altitude, the constraint is deleted when the altitude select knob is pushed. If there are multiple constraints, they are deleted one at a time with each push of the knob. In VNAV altitude hold at a constraint altitude and with the MCP altitude set in the direction of the cruise altitude (in climb) or descent altitude (in descent), the constraint is deleted when the altitude select knob is pushed. In addition, this deletes any constraints below the airplane (in climb) or above the airplane (in descent).
Cruise Altitude Change Altitude Intervention The AFCS MCP is also used for altitude intervention. The FMC uses the altitude display and switch behind the altitude select knob to: - Delete altitude constraints - Change FMC cruise altitude - Capture the MCP altitude
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In VNAV climb if the MCP altitude is set above the active cruise altitude, a push of the altitude select knob causes the cruise altitude to change to the MCP altitude. 34.61.0763A-001
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Cruise Altitude Change (cont) In VNAV cruise if the MCP altitude is set above or below the present altitude, a push of the altitude select knob causes the cruise altitude to change to the MCP altitude. This also causes the FMC to change to VNAV climb or VNAV descent to go to that altitude. If the MCP altitude is below the present altitude and the airplane is within 50 NM of top of descent, the FMC changes to DES NOW.
MCP Altitude Capture If the VNAV profile tries to fly the airplane through or away from the MCP altitude, the FMC captures and holds the MCP altitude. This mode is VNAV ALT. 34.61.0763B-001
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FMCS-EFIS FUNCTION
General The FMC can produce two independent maps for display on the captain’s and first officer’s ND. The FMC shows map data in either the MAP or PLAN modes. Mode control is from the EFIS control panel. The EFIS control panel also has selections for map range and map data selector switches. The CDU can be used to make route modifications, select reference points and step through the plan display.
EFIS Map Processing
The navigation data base also contains the locations of waypoints and ground reference points, and airports which are considered background data. This data is not required to be updated as fast as dynamic data. Dynamic data are parameters and symbology that moves relative to the map display and must be updated at a fast rate. The guidance function provides information for the rotation and translation of the dynamic data.
34.61.0814 -001
The EFIS function gets the lateral flight plan from the guidance function. There are three types of flight plans that can show: - Active - Modified - Inactive Computations are done to smoothly connect all waypoints of the route. The EFIS function also searches the navigation data base for all navaids that exist in the display area. This information is used in the navigation radio tuning function as well as in the formatting of the map display.
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FMCS - CONTINUOUS FAULT MONITOR
General The FMCs are self monitoring with BITE (built in test equipmenthardware and software monitors). The continuous fault monitor monitors the health of the FMC at power up and during operation.
Operation The continuous monitor performs these activities during operation: - Power up BITE tests - All input sensors SSM - All ARINC receivers - All ARINC transmitters - Internal processor tests
Test Results The results of the continuous monitor tests are sent to the test failure response logic. When certain failures occur a rerun of power up BITE is requested. If the power up test passes, this may lead to a request to resynchronize from the other FMC. The FMC that is resynchronized shuts down its output bus during this time.
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When test results cause the FMC to fail, the CDU shows the MENU page and the select caret and FMC (AUTOTHROT DISC (CAUTION) master caution lights and aural if the autothrottle was engaged. - >FMC LEFT or >FMC RIGHT (ADVISORY) - >FMC MESSAGE (ADVISORY, this indicates that an alert message is in the CDU scratchpad)
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Test Results (cont) The PFD and ND show these displays: - PFD shows a blank A/T FMA - ND shows the MAP and VTK flags The VTK flag shows right away, and the MAP flag shows after 30 seconds. The fail light on the front panel of the FMC comes on when the FMC has shut down due to a detected failure. Cycle power to the FMC to run the power up BITE. If the fault was caused by a software error, the FMC may resume operation. 34.61.0764B-001
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FMCS-RESYNCHRONIZATION
General
FMC Internal Test Failure
An FMC will resynchronize the other FMC if one of these two conditions ocurrs: - If the calculated data from the two FMCs does not match properly
If either FMC fails an internal test, its output buses are shut-down. The test failure response logic will cause a restart of the FMC. After the restart, the FMC needs to be resynchronized. The slave can resynchronize the master.
- If one FMC fails an internal test and can not operate unless it goes through a restart
Resynchronization Indications
Data Comparison Failure Some guidance data calculated by each FMC is transmitted on the intersystem bus to the other FMC. Each FMC compares the other FMC’s data with its own data. If there is a difference between the data of the two FMCs, the master FMC starts a resynchronization of the other FMC. The process takes about 15 seconds.
If the FMC that needs resynchronization is the master FMC, and if VNAV, LNAV and autothrottle are engaged, then the indications occur as shown on the chart. The main EICAS, PFD and ND will all show a loss of the master FMC.
During resynchronization, flight plan and performance data goes to the other FMC. During resynchronization, the master FMC can perform all functions normally.
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FMCS - CDU MESSAGES
General
Alert Messages
The FMCs can show an alert for conditions that reduce its functions. There are two types of messages. They are alert and advisory messages. The alert and advisory messages turn on the message (MSG) annunciator light on the CDU.
Alert messages have a higher priority than advisory messages and therefore, show before or replace advisory messages. Alert messages have priority over any other message in the scratch pad. If an alert message is already in the scratch pad when another alert message is received, the new alert message is shown. The previous message is stored in a stack type configuration.
Only the alert messages set the CDU MESSAGE output discrete to show FMC MESSAGE (level C) on the main EICAS. Uncleared messages (not removed) and uncleared alphanumeric data are stored in a message stack. As alert messages occur, they are shown in the scratch pad of each CDU. As uncleared alert messages are replaced by other alert messages, they are added to the top of the stack. As the CLR key is pushed, in steps, the stack is shown and messages and data are cleared in sequence from the top to the botton. When the CLR key is held, it does not cause all messages to be cleared continuously.A CDU message will clear if the logic that caused the message is reset or if the CLR key on the CDU is pushed.
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Display of all alert messages is inhibited below 500 feet altitude above ground level (AGL) during approach when a runway is in the active route. If there are more alert messages during this time, they will be shown at flight completion or after the airplane climbs through 1000 feet AGL. Alert messages only set the CDU message output discrete to show FMC MESSAGE (level C) on the main EICAS.
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Advisory Messages There are two types of advisory messages. They are data entry error advisory messages and basic advisory messages. Data entry error advisory messages have priority over the advisory messages. The advisory messages are shown only on the CDU where the condition occurred. All advisory and alert messages cause the CDU MSG lite to come on. 34.61.0769B-001
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FMC - THRUST MANAGEMENT - INTRODUCTION
Autothrottle
Thrust Limit
The autothrottle (A/T) is armed by a switch on the MCP and TO/GA switches. The autothrottle mode is determined by mode selection on the MCP. The FMC sends a command to the A/T servo to move the throttle levers. The A/T servo moves the throttle levers and provides a rate feedback to the FMC.
The thrust limit calculation is done by the FMC with the mode of operation and other factors such as temperature, ambient pressure and barometric altitude which affect the thrust limit. The FMC also calculates a maximum limit which is sent to the EIUs and the EECs.
As the throttle levers move either by A/T or manual (pilot) input, the throttle resolver angle (TRA) transducers send throttle position data to the electronic engine controls (EECs). The EECs send data to the fuel control units to do a coarse adjustment of the engines. The engines provide thrust feedback to the FMC through the EIUs.
34.61.0770 -001
Engine Trim Engine trim equalization occurs during both manual and autothrottle operation. In this process, the FMC uptrims the trailing engines to match the highest engine thrust until it reaches the trim authority limit. If equalization is not achieved, downtrim then occurs for the leading engine. To do this, the FMC receives actual engine thrust from the EIUs and then calculates the trim commands. These commands are sent through the FMC master relay No. 2 to the EECs.
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FMCS - THRUST MANAGEMENT FUNCTION
General The thrust management function of the FMC has two functions. These are autothrottle and thrust limit.
The control laws function calculates the autothrottle command with the mode of operation.
The thrust management function requires sensor inputs from ADCs, IRSs, EIUs, flight deck analog signals, MCP and the offside FMC. The received data is used to control the throttles for the airplane’s flight path operations and for thrust limit calculation.
The mode logic in the processor allows for manual or automatic selection of available throttle modes. The engine trim function calculates thrust equalization commands for the leading and trailing engines with a maximum trim authority of five percent below 20,000 feet and ten percent above 20,000 feet.
Autothrottle The autothrottle processor produces servo control commands, thrust equalization outputs to the EECs and data for EICAS, CDU and PFD display. There are four activities done in the autothrottle control processor: - Engage logic - Control Laws - Mode logic - Engine trim The engage logic function determines the validity of the control law data and enables the software control laws. This function enables the servo motor excitation voltage.
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Thrust Limit Calculation The thrust limit calculation supplies the autothrottle control function with the maximum and reference thrust limits. These thrust limits show on the CDU and main EICAS. The processor receives mode requests from the CDU and MCP and data from external sensors and analog switches. Calculations include fixed derates and assumed temperature derates. 34.61.0771 -001
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FMC - THRUST LIMIT CALCULATION
General The thrust limit calculation produces two limits. These are: - Maximum thrust - Thrust limits/THR REF
Maximum Thrust The maximum thrust is calculated for display on EICAS. The maximum thrust is not reduced by any mode or derate selection.
Thrust Limits and THR REF The thrust limit is calculated for display on the CDU and main EICAS and for the autothrottle to use as a limit value. This limit is calculated for the mode selected. 34.61.0772 -002
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FMCS - AUTOTHROTTLE ENGAGE LOGIC
General The autothrottle engage function monitors airplane and FMC parameters for autothrottle engagement. If conditions allow autothrottle engagement, excitation power is sent to the servomotor. The throttle hold mode removes excitation from the servomotor but does not disconnect the autothrottle.
In this situation, the A/T DISCONNECT message will not occur. The A/T DISCONNECT is a level B message which also causes a master CAUTION annunciation.
34.61.0773 -002
Servo Loop Monitor When engaged, the autothrottle sends a command to the servomotor which sends throttle rate data (tachometer) back to the FMC. The autothrottle compares these two signals and disconnects excitation to the servomotor if the signals do not generally agree. This is called the servo loop monitor and is used to detect failures in the autothrottle system.
Autothrottle Disconnect The A/T DISCONNECT message shows on EICAS when the autothrottle goes from an engage status to off. This occurs for any condition (manual or automatic) but not for disengage on the ground with thrust reverser application.
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FMCS - AUTOTHROTTLE CONTROL LAWS AND MODE LOGIC
General There are three processes for autothrottle control. These are: - Speed - Vertical speed - Thrust The mode logic determines the selection of these processes.
Speed Two modes are in the speed control process. These are VNAV speed mode and MCP speed mode. The VNAV speed mode uses a true airspeed (TAS) supplied by the FMC performance function. This speed is compared with the air data computer (ADC) airspeed and an airspeed error is generated. The control law calculates a throttle command with this error. Thrust limit protection is maintained to make sure engines do not overboost. The MCP speed mode uses the MCP airspeed, changes it to TAS and operates in the same way as the VNAV speed mode discussed above. Also, both of these modes can operate to hold mach in
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addition to airspeed.
Vertical Speed The vertical speed process calculates a vertical speed for the flight level change (FLCH) mode and provides a set vertical speed (2000 FPM) for the go around (GA) mode. The control law calculates a thrust setting. If the vertical speed reduces below that needed, the control law applies more thrust. However, if the vertical speed is above that needed, the control law does not reduce thrust.
Thrust The thrust process operates to maintain the engines at takeoff (TO), full go around (GA) or VNAV climb/descent thrust limit modes. The control law does not, however, allow the engines to go over the Vmo/Mmo limit.
34.61.0774A-002
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Mode Logic The autothrottle modes when engaged shows on the primary flight display (PFD) in the A/T sector. These are the selectable A/T modes from the mode control panel (MCP): - THR (thrust) when selected causes the control section to control to the full thrust limit of the active thrust limit mode shown on the EICAS display - SPD (speed) when selected causes the SPD control section to control to use the MCP speed as a target - FLCH (flight level change) causes the vertical speed control section to control to a vertical speed that captures the MCP altitude in 125 seconds
These are the selectable modes from the throttle control stand (TO/ GA switches): - Takeoff (TO) selection causes the thrust section to control to the TO thrust limit mode when selected on the ground. The thrust limit mode shows on the main EICAS. - Go-Around (GA) selection causes the vertical speed (V/S) section to control to a V/S of 2,000 fpm. A second push causes the thrust control section to control to the full GA thrust limit mode that shows on the main EICAS display. The A/T arm switch must be on to engage the TO or GA mode. 34.61.0774B-002
- VNAV when selected causes the speed control section to control to an FMC calculated speed and the thrust control section to control to an FMC reference thrust The autothrottle arm switch and a flight director (F/D) or an autopilot (A/P) engaged are necessary to engage an autothrottle VNAV or FLCH mode from the MCP. The A/T arm switch must be on to select the SPD or THR mode from the MCP.
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Mode Logic (cont.)
Servo Control
The flare retard mode, when engaged, causes the A/T servo to drive the throttles to the AFT mechanical stop at 5 degrees per second. The AFDS sends a flare retard request during a LAND-3/LAND-2 condition. This occurs at 65 kts. - VNAV idle descent.
Test shows when one of the three FMC tests is active: - FMC push button (FMC front panel) - FMC ground test (CDU and CMC)
Thrust (THR) shows when the FMC receives a request and enters VNAV descent, FLCH or a GA thrust mode. Thrust reference (THR REF) shows when the FMC thrust function is in a takeoff (TO), VNAV, go-around (GA) or THR (MCP THR button) thrust mode.
- FMC ground test, servo loop (CDU and CMC) The A/T mode blanks when no mode is active or the A/T arm switch is off.
34.61.0776 -001
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FMCS - AUTOTHROTTLE FLIGHT PROFILE
General The autothrottle function of the FMC may be used in all phases of the airplane’s flight: - Takeoff - Climb - Cruise - Descent - Approach - Go-around - Flare
- Speed - Thrust reference
If VNAV is used for climb, the A/T mode is THR REF. If FLCH is used, the A/T mode is THR. If the AFDS is in vertical speed or if the autopilot and flight director are both off, speed or thrust reference may be selected as the A/T mode.
Cruise Takeoff In takeoff, the autothrottle controls the thrust to takeoff limit. The A/T mode is THR REF. At 65 knots, the A/T mode changes to HOLD.
Climb Climb can be done with the autothrottle in four ways: - VNAV - Flight level change (FLCH)
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Cruise can be done with the autothrottle in three ways: - VNAV - Speed - Thrust reference If VNAV is used in cruise, the A/T mode is SPD. If the AFDS is in any mode but VNAV, or if both the autopilot and flight director are off, speed or thrust reference may be selected as the A/T mode. 34.61.0777A-001
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Descent
Flare Retard
Descent can be done with the autothrottle in three ways:
Flare retard occurs on approach with a command from the AFDS. The A/T mode annunciation is IDLE on the PFD.
- VNAV - Flight level change (FLCH) - Speed In VNAV descent, the A/T mode is IDLE or it may be HOLD if the throttles reach the aft stops as a result of the idle mode or pilot override. If FLCH is used, the A/T mode is THR or it may be HOLD for the same reason as for VNAV. If the AFDS is in vertical speed or if the autopilot and flight director are off, speed may be selected as the A/T mode for descent. Thrust reference is a possible mode for descent, but it would not be a normal situation.
A/T Disconnect The autothrottle disconnects with thrust reverser application or at the selection of the pilot. 34.61.0777B-001
Approach In approach with glide slope active or in a manual approach, the normal mode is speed. Go-Around A go-around mode request with autopilot or flight director on, the A/T mode is THR. If the autopilot and flight director are off, the A/T mode is THR REF.
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FMCS - AUTOTHROTTLE OPERATION TAKEOFF
Mode Selection The takeoff mode is engaged with these conditions: - Autothrottle armed - Airplane on the ground - Flap position not zero - Thrust limit mode is TO (default on ground) - Push go-around switch - < 50KTS CAS
Takeoff Mode Operation After a test is done to make sure the servo excitation can be removed, the throttles will move to achieve the TO thrust limit. 34.61.0778 -002
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FMCS - AUTOTHROTTLE OPERATION - VNAV CLIMB
General The VNAV mode may be selected above 400 feet altitude. If selected before this altitude, VNAV is armed and will be engaged when the altitude is reached.
Operation During climb, the thrust limit mode changes from TO to CLB at the thrust reduction altitude or flaps 5. The thrust reduction altitude is the altitude when the flaps reduce to five degrees or a crew selected altitude. The altitude is selected on the TAKEOFF REFERENCE page.
34.61.0779 -002
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FMCS - AUTOTHROTTLE OPERATION - VNAV CRUISE
When the airplane reaches the FMC flight level altitude or the MCP altitude, the thrust limit mode changes to CRZ and the autothrottle mode changes to SPD. 34.61.0780 -002
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FMCS - AUTOTHROTTLE OPERATION - VNAV DESCENT
In VNAV DESCENT, the autothrottle mode is IDLE. If the flight crew moves the throttle manually or if the mechanical stop is reached, the mode changes to HOLD. 34.61.0781 -002
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FMCS - AUTOTHROTTLE OPERATION - SPEED
Mode Selection The speed is engaged when there are these conditions: - Autothrottle armed - Airplane in the air >400 feet - Thrust limit mode not takeoff - Go-around mode not active - FLCH mode not active - VNAV mode not active - Select speed mode on MCP or - Default SPD selection, for example, exit of FLCH or VNAV
Operation In the SPD mode, the autothrottle moves the throttles to control the airplane speed to the MCP selected speed. Thrust limit, speed limit and flap speed limit protection is provided.
34.61.0782 -002
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FMCS - AUTOTHROTTLE OPERATION - FLIGHT LEVEL CHANGE
Mode Selection The FMCS operates in the FLCH mode when: - The autothrottle is armed - The AFDS engages FLCH Operation The FMC uses the difference between present altitude and the MCP altitude to calculate a vertical speed to capture the MCP altitude. The MCP synchronizes to the current airspeed when the FLCH mode is requested. The autothrottle control laws command a thrust which produces a vertical speed to complete the altitude change in 125 seconds. The thrust is limited to the thrust limit mode. During the FLCH mode, if an override occurs, the autothrottle mode changes to throttle hold. HOLD shows as the mode on the PFD. This results from an eight degree difference between the throttle position and the commanded position. This difference can be caused by a pilot override or it occurs when the throttles reach the aft mechanical stops during a FLCH descent with a large altitude change. 34.61.0783 -002
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FMCS - AUTOTHROTTLE OPERATION THRUST
Mode Selection The thrust reference (THR REF) mode is engaged when these conditions are in effect: - Autothrottle armed - Airplane above 400 feet AGL - Not TO THR LIM - FLCH mode not active - VNAV mode not active - Not GA THR LIM - Select THR mode on MCP
Operation In the THR REF autothrottle mode, the throttles move to control the limit speed (either Vmo/Mmo or flap). Thrust limit protection is provided. It may seem that this statement is not correct and that the throttles should control to the thrust limit, with limit speed protection. If this were the situation and the limit speed were close to present speed, the airplane could go over the limit speed before the thrust were reduced. At the least, this situation would cause large throttle changes.
34.61.0784 -002
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FMCS - AUTOTHROTTLE OPERATION - GO-AROUND
Mode Selection The go-aground mode is engaged when there are these conditions: - Autothrottle armed - Airplane in the air - AFDS glideslope engaged or flaps not zero - Thrust limit mode not TO
Operation When the go-around (GA) lever on thrust lever 2 or 3 is pushed, the autothrottle mode changes to THR. For this mode the autothrottle controls to 2000 FPM vertical speed. A second push of the GA lever cause the autothrottle mode to change to THR REF. In this mode autothrottle controls to the full GA thrust limit. 34.61.0785 -002
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FMCS - NAV DATA CROSSLOAD PAGE
General The maintenance pages show maintenance related data that is accessible on the ground. Selection of the MAINT> line select key on the INIT/REF INDEX page causes the MAINTENANCE INDEX page to show. The maintenance pages are:
- (3L) TRANSMIT/RECEIVE: crossload is by selection of key 3L on one CDU followed by 3R on the other CDU, if ARM has been entered on line 6R.
- Performance (PERF) factors page
- (4L and 4R): before transfer starts, this line is blank. During transfer, TRANSFER IN PROGRESS shows, and TRANSFER COMPLETE shows at the end of the data cycle. If the cycle is incomplete TRANSFER ABORTED shows.
- Inertial reference system (IRS) monitor page
- (6L) INDEX: this key selects the MAINT INDEX page.
- BITE report
- (6R)---: type ARM into the scratch pad and push this key. This arms the crossload function. To cancel the arm status go to another CDU page.
- Navigation data (NAV DATA) crossload page
NAV Data Crossload Page 34.61.0786 -001
This page is used to transfer the navigation data base of one FMC to the other to save time. This page shows automatically at power-up if the FMCs detect a navigation data base difference. The function of this page is discussed by the operation of each line. - (2L) Navigation data base identifier: this line is the same as the identifier shown on the IDENT page.
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FMCS - PERF FACTORS PAGE
Performance Factors Page Entries on this page modify the performance factors and causes the related value to show on the TAKEOFF REFERENCE page. This occurs at the end of each flight or after a long term power interrupt. - (1L) PERF CODE: this line shows the binary state of the PERF OPTION CODE hardware program pins which are not active on 747-400. - (2L) DRAG/F-F (fuel flow): the FMCs use this in the performance calculations to improve the accuracy in its performance predictions. The allowable entry range is -/+ 9.9 Fuel flow requires a slash (/) for entry. The DRAG/F-F factors also show on the IDENT page.
- (6L) INDEX: this key selects the MAINT INDEX. - (1R) OPTION CODE: this line shows a hexadecimal number which represents the customer’s options in software (S/W). Option code disagreement between the FMCs causes the last FMC that powers up (or the nonmaster in a simultaneous power up) to show and lock up on the PERF FACTORS page. - (2R) R/C CLB: the minimum rate of climb (ft/min) for max altitude calculations at climb speed and maximum climb thrust. The entry range is from 0 - 500. 34.61.0787A-002
- (3L) TO 1/TO 2: this field shows a manual entry for a fixed derate percentage from 0-30%. TO 2 requires a slash (/) for entry. These values also show on the THRUST LIMIT page. - (4L) MNVR MARGIN: the FMCs use this data for flight envelope and bank limit calculations. Entries range from 1.20 - 1.30. - (5L) MIN CRZ TIME: the FMCs use the minimum cruise time (minutes) for optimum altitude calculations.
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Performance Factors Page (cont) - (3R) THR/CRZ: this line shows the minimum rate of climb margin (ft/min) for maximum altitude calculations at cruise speed and maximum climb at cruise thrust. Entry ranges are CLB or CRZ / 0-500. Default entry for thrust is the last entry or CLB if no previous entry. Default entry for rate of climb is 100 with no previous entry. - (4R) THR RED: this line shows the altitude or flap setting when the thrust limit automatically changes from TO to the preselected CLB thrust limit mode. - (5R) ACCEL HT: this line shows the flap retraction height when acceleration begins in V-NAV for flap retraction. The inner field shows engine out altitude. Entry range is from 400-9999. - (6R) ARM: type ARM into the scratch pad and push this line select key. This arms the PERF FACTORS page to modify all values except the H/W and S/W option codes. 34.61.0787B-002
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FMCS - IRS MONITOR PAGE
IRS Monitor Page The IRS monitor page shows an estimate of position error rate for the IRUs at the end of each flight. The maintenance crews can use this data to help determine if an IRU has excessive position drift. Position error rate is calculated by dividing distance from the FMC position to the IRS position by the total flight time. This value is calculated at flight completion and is displayed approximately 45 seconds after all engines shut down. These values clear when in the air, or if power is cycled. (6L): this line selects the MAINT INDEX page.
34.61.0788 -001
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FMCS-BITE REPORT PAGE
Push the line select key next to BITE > on the MAINTENANCE INDEX to show the BITE REPORT page. The BITE REPORT page allows the FMC BITE history to be transferred to the data loader. This data may be used by the manufacturer to analyze faults in software and hardware. A pre-formatted disk with the proper file is required to perform this task. The prompt DATA LOADER shows when the page is selected. The caret symbol () shows. Select the GND TEST MSG page(s) to determine if the failure is an FMC and/or an interface fault.
34.61.0789A-001
- SYSTEM TEST: a power up BITE is started when the PB SWITCH is pushed. The IN PROCESS LED stays on for the BITE duration of 15 seconds. The FAIL LED comes on at the end of the test when an internal or servo failure is detected. At test completion the FMC normal functions are restarted through the power-up BITE.
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FMCS - BITE AND SYSTEM TESTS
Bite and System Test Results The IDS shows status data and test data on these displays: - EICAS shows AUTOTHROT DISC, FMC LEFT/FMC RIGHT and FMC MESSAGE. The master caution lights and four beeps of aural tone is observed with the AUTOTHROT DISC display. - EFIS shows normal PFD and ND data and test data when an FMC push button test or CMC test is in progress. The PFD shows the word TEST, in green, in the autothrottle flight mode annunciator sector. The ND shows FMC I/O TEST OK in green above the FMC position during the test. The BITE results after a failure causes the PFD A/T FMA to go blank. The ND shows MAP and VTK (vertical track) flags.
The offside CDU shows the message RESYNCHING OTHER FMC or SINGLE FMC OPERATION in the scratchpad. The offside CDU MSG light comes on right away. The FAIL light comes on after 30 seconds during the test. The onside CDU FAIL light stays on when the test fails. 34.61.0789B-001
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FMCS - FMC GROUND TESTS (SHEET - 1) General Two tests of the FMC can be done from the CMC. These are: - Flight management computer - Flight management computer servo loop
An autothrottle servo communication (FMC system test) and power up are then started. Some throttle motion may occur in the communication test. The CMC shows test pass/fail data after 45 seconds from the results of the communication test, the FMC BITE, and LRU status.
These tests are inhibited if: SERVO LOOP Test - The engines are not shut off. - The autothrottle servo is engaged. - The airplane is in the air. - The master FMC is not tested. - The A/T ARM switch is off. When CMC on the MENU page is selected, it shows the CMC MENU page. When GROUND TESTS is selected, the GROUND TESTS MENU page shows. When 34 FLIGHT MANAGEMENT is selected GROUND TESTS MENU page 1/2 shows.
This test causes large throttle movements and includes part of the previous test. The throttles move aft to the idle position then forward for 5 seconds. Aft throttle travel occurs again for 5 seconds to conclude the test. The SERVO LOOP test passes if throttle rate is between 6-10 degrees per second. FMC - ENABLE Page The FMC TO ENABLE TEST page shows the FMC INHIBITED for three conditions:
Flight Management Computer Ground Test All LRUs that have interface with the FMC must operate correctly for this to pass. IDS and CDU displays for test results are the same as described for FMC system test.
- The FMC is not the master as defined by the master switch on P2. - Any engine in the run condition (RPM). - Airplane in the air (AIR/GND logic). 34.61.0802 -001
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FMCS - FMC GROUND TESTS (SHEET - 2)
General Push the line select key next to the desired test to start the ground test. If the test is not inhibited, a test preconditions page shows. The operator must verify the airplane meets these test preconditions for the test to work properly.
Operation Push the line select key next to START TEST> to begin the ground test. An IN PROGRESS screen shows for approximately 45 seconds. At test completion, the ground tests page shows with the test results. If FAIL> shows, push the line select key to show the ground test message page. 34.61.0801 -001
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34.61.0302 -001
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FMCS - MODE CONTROL PANEL GROUND TEST (SHEET 3)
General A test of the AFCS mode control panel is done to examine the FMC interface with the MCP and the operation of FMC functions on the MCP. A maintenance person must do many steps during this test. Only a few of the steps are FMC functions. When the key next to 22 AUTOPILOT FLT DIR is pushed, the AUTOPILOT FLT DIR ground test menu shows. The AUTOPILOT FLT DIR tests can not be done if the airplane is in the air or if an autopilot servo is engaged. The key next to MODE CONTL PANEL is pushed to start the MCP test.
Mode Control Panel Test During the test, the MCP thrust and speed select switches and the autothrottle arm switch are tested along with other AFDS functions. Pass/fail data is sent to the CMC and shows on the CDU. 34.61.0803 -001
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34.61.0303 -001
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FMCS - CDU BITE AND FAULT MONITOR
General CDU BITE operates almost the same as FMC BITE. There is a power up part and a continuous monitor part. A difference is that detected failures are stored in volatile RAM for CDU BITE instead of in nonvolatile memory for FMC BITE.
cause a request to rerun BITE, or cause the CDU to fail if repeated failures have occurred. Test results are stored in RAM (volatile memory) for shop inspection. CDU failure status is shown on the auxilliary EICAS if the CDU is selected on the NAV source select switch.
Power-Up BITE Tests
CDU test failures cause the CDU screen to go blank.
Power-up BITE is a group of tests that are done when the CDU is turned on or if BITE requests a restart. The tests are done on memory, processors, transmitters and computation functions.
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Continuous Monitor Tests Monitor tests are done during normal CDU operation. These tests do not affect normal operation. These tests include some of the power-up BITE tests. They also include hardware tests and a heartbeat monitor.
Test Failure Response Logic Failures detected by power-up BITE and by continuous monitor
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FMCS - DATA LOADER OPERATION
General This discussion is for the operation of the airborne data loader (ADL) to load the FMC navigation data base (NDB) with 3.5 inch diskettes. While a navigation data base load occurs, the FMC output buses are turned off. This causes indications in the flight deck. These indications are shown on the CDU, EICAS, ND and the PFD. Indications in the flight deck are the same for an operational program load.
- Remove and insert the next disk when the CHNG light comes on - Monitor ADL lights for transfer complete indication (loading takes about 20 minutes) - Remove the floppy disk and close disk drive door - Turn the ADL control panel selector switch to NORMAL
FMC Data Load Procedure (NDB)
- Close the circuit breaker(s) that are opened for this procedure
These are the steps in the data load procedure:
- Look to see that the data base is correctly updated (the IDENT page on the CDU is used to do this)
- Look to see if the circuit breakers for FMC, CDU (P7) and FMCS data base loader (P6-4) are closed
- Load the other FMC by crossload (about 10 minutes) or do the above procedure on the other FMC
- Pull the circuit breaker for the FMC which is not loaded - Select NORMAL on the ADL control panel selector switch - Select the left or right FMC on the ADL control panel selector switch
NOTE: For crossload, select the IRUs in the NAV mode or select the transmitting FMC as master to do the crossload procedure. Do not stop the crossload procedure once it is started. If stopped, this causes the receiving FMC to be latched on the crossload page. The crossload procedure must be repeated in this case.
- Open disk drive door and put the disk in the ADL 34.61.0793A-002
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Indications During Load (NDB)
FMC Data Load Procedure (OP-PROG)
When the ADL control panel switch is selected to the FMC to be loaded, these indications occur:
Steps to load the FMC operational program are similar except:
- The FAIL annunciator on the CDU comes on
- Each FMC receives a separate load - The load time is about 10 minutes - Observe the S/W P/N on the IDENT page at line 4L
- The MENU page shows on the CDU but the FMC prompt and (if it was present) is deleted 34.61.0793B-002
- On EICAS, the FMC LEFT/RIGHT advisory message shows after 30 seconds - On the ND, the VTK flag shows immediately and the MAP flags show in approximately 35 seconds - On the PFD, the NO V SPD flag shows - The COMP light comes on in 20 minutes if data transfer is successful for a navigation data base load (it takes about ten minutes for an operational program load) - When the disk is put in, the RDY light comes on in five seconds and two to three seconds later the PROG light comes on (Disk Activity light flashes when the disk is being read) - When the disk is removed, all ADL LED lights go off
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FMCS - FLIGHT DECK EFFECTS
General This is a summary of all maintenance related flight deck effects for this system.
- FMC LEFT/RIGHT (status): this shows on the auxiliary (AUX) EICAS after 60 seconds with an FMC failure and is latched for maintenance action.
Flight Deck Effects
- CDU LEFT/CENTER/RIGHT (status): this shows on the AUX display when the CDU is selected on the NAV source switch and it has failed for 10 seconds or more.
These EICAS messages occur with level of importance when the FMC detects a non normal condition: - >AUTOTHROT DISC (caution): this shows when the master FMC detects a manual or automatic autothrottle disengage (except when the autothrottle disengages on landing with thrust reverser applied).
These EFIS displays occur when the FMC detects a non-normal condition: - The PFD shows a blank A/T flight mode annunciator (FMA). - The ND shows a MAP and VTK flags
- >FMC LEFT/RIGHT (advisory): this shows when the related FMC detects an internal failure, external sensors invalid or ARINC data buses fail. - >FMC MESSAGE (advisory): the FMC shows an alert message in the CDU scratch pad when flight crew inputs are required by the flight management system.
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The CDU shows a message in the scratchpad RESYNCHING OTHER FMC or SINGLE FMC OPERATION. The MSG light comes on right away and the FAIL light comes on after 30 seconds when the FMC detects a failure. 34.61.0794 -001
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FMCS - CMCS MESSAGES - 1
General This is a summary of all CMCS fault messages for this system.
CMCS Messages The CMC messages that may occur during system operation are in these categories: - Component failure - Interface failure Some CMC messages occur during ground tests. 34.61.0795 -001
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FMCS - CMCS MESSAGES - 2
General This is a summary of all CMCS fault messages for this system.
CMCS Messages The CMC messages that may occur during system operation are in these categories: - Component failure - Interface failure Some CMC messages occur during ground tests. 34.61.0796 -001
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