Lecture 9-Ground Proximity Warning System (GPWS)

Lecture 9: Ground Proximity  Warning System (GPWS GPWS))

By: Zuliana Ismail,2010

What is GPWS? Home

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 A Ground Proxi Proximity mity Warni Warning ng System System (GPWS) (GPWS) is a type of equipment carried by aircraft to warn they are at a dangerously low altitude pilots if  and in danger of crashing.

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The pilots are alerted through visual and audio warnings by GPWS display inside cockpit.

Purpose of GPWS Home

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 The main main purpose purpose of of these syste systems ms is to prevent what is called a Controlled Flight Into Terrain (CFIT)

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 CFIT is an accident in which an aircraft crashes into the ground, the water, or an obstacle such as a mountain or building bu ilding .

CFIT= Controlled Controlled Flight Into T  errain errain Home

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Since

1960s, a series of  Controlled Flight Into Terrain (CFIT) accidents killed hundreds of people.

CFIT  and Home

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GPWS

 CFIT can be the the result result of factors such as navigation

errors, pilot fatigue, or or reduced visibility owing to weather conditions.

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 CFIT incident incidentss have been reduced since GPWS entered entered widespread use in the 1970s.  The use of a GPWS in large aircraft aircraft is required required by law in many countries.  In the late late 1990s improvements were made made and the system was renamed "Enhanced Ground Proximity Warning System (EGPWS)

Visual

How

Audio

GPWS Works?

 RA measures how far aircraft from the ground.

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 GPWS GPWS co compu mpute terr analyzed the information from radar.

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(RA)

What is the different between radar  altimeter and barometric altimeter?

 Comp Comput uter er can identify hazardous situations (very close to ground/terrain,, rapid ground/terrain ROD & loss of altitude)  GPWS display gives visual and audio warning signals to the pilot.

How

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GPWS Works?

 A GPWS monitors the aircraft's altitude with a Radar Altimeter, which transmits radio waves downward from the plane to determine how far away the ground is.  Most radar altimeters carried by commercial aircraft are shortrange devices with ranges of less than a mile (about 1.6 km).  The inform informatio ation n from the radar radar is monito monitored red and analy analyzed zed by by a computer that can identify hazardous situations and trends in the data, such as  a dangero dangerously usly rapid rate of of descent, descent,  dangerously close ground during, or  unexp unexpected ected loss of altitu altitude. de.  If hazardo hazardous us conditio conditions ns are detec detected, ted, the the GPWS GPWS gives gives visual visual and and audio warning signals to the pilot.

Radar

Altimeter Vs Barometric Altimeter Home

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What is the different diff erent between radar altimeter altimeter and barometric altimeter?  A Radar Altimeter (RA) measures the distance between the plane and the ground directly below it.  Barometri Barometricc alti altimeter meter provides the distance above sea level.

Audio & Visual Warning  Audio Audio & Visua Visuall Warnin Warnings gs are prov provided ided under any of the following conditions:

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 Excessive rate of descend (sink rate)  when closure rate with terrain is too high (terrain-terrain)  loss of of altitude altitude after take-off take-off (dont (dont sink)  if the aircraft is too low and and slow, with landing gear retracted (too low, gear)

GPWS Modes WARNING

MODE Home

Mode 1: Excessive Descent Rate. Previous

Mode 2: essive Terrain Closure Rate Exc Next 

when Rate of  Descent(ROD) increase rapidly

sink rate, sink rate

whoop, whoop, pull up, pull up

when closure rate with terrain is too high.

terrain, terrain

whoop, whoop, pull up, pull up

warn loss of altitude after take-off.

dont sink

Too low, landing

gear/flap configuration.

too low, terrain too low, gear too low, flaps

Mode 5: Descent below Glide Slope

Too low

Glideslope

Mode 6: Situation Awareness

Bank Angle, Altitude

Minimums Bank Angle

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Mode 3: Descent after take-off 

Mode 4: Unsafe Terrain Clearance

Mode 7: Wind shear Information

Wind Shear

MODE 1: Excessive Descent Rate.. Home

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 Warns of  Descent(ROD) excessive Rate of   A GPWS warning warning light will illumi illuminate nate and and sink rate, sink rate will be heard.  If the situa situation tion is not corre corrected cted whoop, whoop, pull up, pull up will be heard.

MODE 2: Excessive T  errain Closure Rate errain Home

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 Warns crew when closure rate with terrain is too high.  Designed to warn crew when rising terrain terrain is is a threat.  terrain, terrain  whoop, whoop, pull up, pull up  There may be no change in barometric altitude but the radar altitude is decreasing.  Recovery: Continue climb until clear of terrain. terrain.

MODE 3: Altitude Loss After T  ake-off  ake-off  Home

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 Warns of  loss of altitude after take-off.  If the aircraft sinks 10 percent of its radar altitude dont sink will be heard.

MODE 4: Unsafe T  errain Clearance errain Home

 Terrain clearance while aircraft take-off, climb, cruise, and descent.

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 If the airspeed is higher the warning will be too low, low, terrain Next 

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 Alert the configuration configuration of landing landing gear gear during during approach. approach. the aircraft is too low and slow, with landing gear retra cted  if  (not open).  too low, gear

 Alert the configurati configuration on of of flaps during landing  When the gear is selected down, down, but the flaps are still retracted (not open)  too low, flaps flaps

Mode 5, 6, 7 Home

 Mode 5: Descent Descent below Glide Slope

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 Mode 6: Situation Awareness (Bank Angle, Altitude)

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 Mode 7: Wind Wind shear shear Informa Information tion

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