Perfo Briefing 737

B737 Performance Takeoff & Landing Last Rev: 02/06/2004

Takeoff Performance       

Takeoff Performance Basics Definitions: Runway Takeoff Distances Definitions: Takeoff Speeds JAR 25 Requirements Engine failure  ptimisation on ± improved improved climb climb O ptimisati Reduced takeoff 

Takeoff Performance       

Takeoff Performance Basics Definitions: Runway Takeoff Distances Definitions: Takeoff Speeds JAR 25 Requirements Engine failure  ptimisation on ± improved improved climb climb O ptimisati Reduced takeoff 

Takeoff Performance Basics What 

is t he Gross Gross Takeoff Flig ht Pat h ?

It

is the vertical flight path that a new aircraft flown by test pilots under ideal conditions would achieve. It is adjusted for the Minimum Engine. It starts where the aircraft passes 35ft and ends at a minimum of 1500 ft

What 

is t he Net Ne t Takeoff Takeoff Flig  Fli g ht Pat h ?

This is the vertical flight path that could be expected in operation with used aircraft . It also starts at 35ft and ends at a minimum of 1500ft

Takeoff Performance Basics 

The Net Gradient would be calculated as follows: Gross Gradient

p% x D Net Gradient

Distance = D

Takeoff Distances  RUNWAY 

This is the AC N capable hard surface

CLEAR WAY - This is an area, under the control of the airport, 152 m (500 ft) minimum width, with upward slope not exceeding 1.25%. Any obstacles penetrating the 1.25% plane will limit the Clearway



STOPWAY -

surface capable of supporting the aircraft in an RTO. Its width must be greater than or equal to that of the runway. It may not be used for landings A

Takeoff Distances CLEARWAY

RUNWAY

STOPWAY

TOR A ASDA

TODA

MAX

1.25%

Takeoff Distances  



  

TOR A- TakeOff Run Available. This is the physical runway limited by obstacle free requirements ASDA - Accelerate-Stop Distance Available. This is the distance available for accelerating to V1 and then stopping. It may include the physical runway and any stopway available TODA - TakeOff Distance Available. This is the distance available to achieve V2 at the appropriate screen height. It may include physical runway, stopway and clearway Note: Not more than ½ the Air Distance may be in the Clearway (Air Distance is distance from lift -off to 35 ft) The Takeoff R un is defined as the distance from brake release to ½ the Air Distance Wet Runway calculations do not allow use of  Clearway

Takeoff Performance Basics The Takeoff Phase is from brake release to 1500 f t or the  point where the last obstacle has been cleared, if higher  Three basic limitations must be taken into account:  Field Length  Climb Gradients  Obstacle Clearance Other   

limitations are also restrictive and are covered during discussion on these basic limitations. They are: Structural Tire Speed Brake Energy

Takeoff Speeds

V1

Takeoff Speeds V1 ³official definition´ ³«pilot's initiation of the first action (e.g. applying brakes, reducing thrust, deploying speed brakes) to stop the aeroplane during accelerate-stop tests«´ JAR

25.107(a)

Takeoff Speeds V1, the Takeoff « action » speed, is the speed used as a reference in the event of engine or other failure, in taking first action to abandon the take-off. The V1 call must be done so that it is completed  by V1. V2

VEF

VEF

V1

V1

35¶

Takeoff Speeds

VR  

VR  is

the speed at which rotation is initiated, so that in the case of an engine failure, V2 will be reached at a height of  35 feet using a rotation rate of  2º-3º / second



Regulations prohibit a RT O after rotation has been initiated, thus VR must be greater than V1. VR  u V1

Takeoff Speeds

V2 

V2 is the takeoff safety speed. This speed will be reached at 35 feet with one engine inoperative.

Takeoff Speeds 

Effects

on the screen height of continuing a takeoff with an engine failure prior to V EF

35 Ft

10 Ft

2 Engine

1 sec

-16

-8

0

SPEED OF ENGINE FAILUR E R ELATIVE TO VEF

+4

+8

Takeoff Speeds  

  

The Minimum Ground Control Speed This is the speed at which, in the case of a failure of the Critical Engine, it is possible to control the aeroplane by aerodynamic means only without deviating from the runway centreline by more than 30 f t, while maintaining takeoff thrust on the other  engine(s). Maximum rudder force is restricted to 68 Kg (150 lbs) In demonstrating V1(MCG), the most critical conditions of  weight, configuration and CG will be taken into consideration Crosswind is not considered in V1(MCG) determination O bviously VEF must be greater than V1(MCG) , or the aircraft would be uncontrollable on the ground with an engine inoperative: V1(MCG) -

VEF u V1(MCG)

Takeoff Speeds  





The Minimum Control Speed This is the speed, when airborne, from which it is possible to control the aeroplane by aerodynamic means only with the C ritical Engine Inoperative while maintaining takeoff  thrust on the other engine(s) The demonstration is made with not more than 5º Bank  into the live engine, Gear retracted (as this reduces the directional stability) and the most Aft C G (as this reduces the Rudder Moment.) (VMC may increase as much as 6 Kts. / º Bank from demonstration with wings level and Ball centred) VMC -

Field 

Length Criteria

The Takeoff distance required for a given weight and given V1 is the greater of three different distances: Actual All-Engine Takeoff Distance x 1.15

Actual All-Engine Takeoff Distance (As Demonstrated in Tests) V1

V

> V2

35 f t

15% Safety Marg in

One Engine Inoperative Takeoff Distance VEF

V1

VEF V1

One Engine Inoperative Accelerate-Stop Distance

V2 35 f t

Field  

Length Criteria

The greater of the 3 distances is the JAR  Field Length required If V1 is chosen such as the 1 -Engine-Inoperative Accelerate-Go and Accelerate-Stop distances are equal, the necessary field length is called Balanced and the corresponding V 1 is known as a Balanced V1 Balanced V1

Field MTOW

Length Criteria

Fixed R unway Length ACCELER ATE GO

R ANGE OF POSSIBLE WEIGHTS

ACCELER ATE STOP

BALANCED V1

V1

JAR

25 Takeoff Flight Path 1500 Ft or Clear of Obstacles

Flap retraction

400 Ft Min

Gear R etracted

Lif t-Off 

V2

V2

Clean

Acceleration

TO Thrust

35 ft

1st Segment

TWIN

>0

M ax

2nd

Segment

2.4%

Clean

M CT

5 min

3rd

Segment

acceleration or 1.2% avail.

4th Segment

1.2%

O bstacle Clearance



For O bstacle Clearance



It

a Net Takeoff Flight Path is considered

is not demonstrated, but rather calculated from the Gross Flight Path by reducing the gradients by a safety margin: Twin

0.8%



It

also will take wind into account, using 50% of the Headwind Component and 150% of the Tailwind Component, thus giving a further safety margin.



The Net Takeoff Flight Path must clear all obstacles by 35 Ft

O btacle

1st Segmen t

2nd

Vs Climb

Segment

3rd

Segment

4th Segment

Gross Flight Path

V2

Net Flight Path 35 ft 35 ft 35 ft 35 ft

O bstacle Clearance 

The minimum height for flap retraction is 400ft



TNT A B737 : we use 800 ft



If



We now have a Minimum Gross and Minimum Net Acceleration Height which is then corrected for elevation and temperature to give a Minimum Gross Acceleration Altitude

AAL

AAL

(gross)

minimum

there is a high obstacle in the 3rd or 4th segment, we could extend the second segment to ensure that the obstacle was cleared by 35ft. Provided it still remains in the 3rd or 4th Segment

O bstacle Clearance

Extended

Second Segment

Minimum

Gross Acceleration Height

Minimum

Net Acceleration Height

35 Ft

400 Ft

Acceleration Altitude



The extension of the second segment and raising of the EFFR A (JAR : EOAA) is limited as takeoff thrust must be maintained until acceleration altitude is attained



The Takeoff Thrust is limited to 5 minutes and this restricts the extension of second segment

Engine Failure

Procedure

The Standard Engine Out Procedure (EOP) is therefore:  Maintain Runway Track   Climb

to the EFFR A at V2

 Accelerate 

and Retract Flaps

Set MCT (max 5 min after TO power setting)

 Climb  And

to the 1500 ft

then???

AGL

at Flap up man. speed

Distance

to clear 1500 ft (B737) 4th segment: 1.2% p 1500ft @ 220kts 70 ft/NM  7 NM 3rd segment: Accel

150kts p 220 kts 0.23m/s²  8 NM 2nd segment:

2.4% p 1000ft @ 150kts 150 ft/NM  7 NM 1st segment: >0% 140 ± 150 kts

0'30"

3'00"

2'30"

2'00"

O bstacle Clearance



Only

obstacles within a certain lateral distance of the flight  path are taken into account in performance calculations



For

each runway, Obstacle Cone is constructed for Straight Ahead or Turning Engine Out Procedures (EOP)



Wind is not considered therefore correct tracking is important



There is not a large margin for error for a jet airplane

O bstacle Clearance Flight

3000 f t

width = 0.125 x D

300 f t

21600 f t

3000 f t

300 f t

3000 f t

Path

O bstacle Clearance Flight

Path

O bstacle Clearance



Bank Angle has a large effect on the climb performance and therefore O bstacle Clearance

GR ADIENT 2.4%

0.6% 1.8%

0

15

30 BANK ANGLE

O ptimisation - Improved 

  



Depending

climb

on the design of the aircraft and on the flap setting, the maximum climb angle speed is usually 15 to 30 kts higher than 1.13 V SR  However, the selection of a V2 higher than the minimum will increase TOD The V2/VS optimisation is called Improved Climb Method » This method consists thus in increasing the climd limited TOW at the expense of the field limited T OW. It is only applicable if runway length permits In order to obtain consistent field length, V1 and VR have to increase if V2 increases: if the runway allows an increase of V2, thus an increase in T OD, it will also allow an increase of the ASD, thus also of V1

O ptimisation - Improved

climb

Drag Drag Curve Given TOW TO Flaps Gear UP

Depending on Flap

Setting,

the Max Angle Speed is typically 1.13 VS + 15 to 30 Kts Vs

1.13Vs

1.28Vs

EAS

O ptimisation - Improved

climb



In

order to achieve the higher V2, the VR speed must be increased



The V1 speed must also be increased to ensure that there is sufficient runway to accelerate, lose and engine and be able to continue the takeoff at higher weight



As

V1 is higher, the V MBE speed must be checked for brake energy limits as this may become limiting

Reduced Thrust Takeoff 



 

When the actual T OW is below the maximum allowable TOW for the actual OAT, it is desirable to reduce the engine thrust This thrust reduction is a function of the difference  between actual and maximum T OW JAA requires that the reduced thrust may not be less than 75% of the full takeoff thrust. Specific figures may apply for different airplanes/engines

Reduced Thrust Takeoff  Assumed

temperature If

the actual TOW is less than the maximum weight for the actual temperature, we can determine an assumed temperature, at which the actual weight would be equal to the maximum allowed TOW

MAX

TOW Allowed

Flat

rated thrust

TOW

EGT

limited thrust

Act

TOW

OAT

Assumed

temperature

Temp

Having determined this assumed temperature, we can compute the take -off  thrust for that temperature

Reduced Thrust Takeoff  Limitations 

Since thrust may not be reduced below 75% of the full thrust, a max assumed temp can be determined



The assumed temperature may not be less than the

OAT



 No reduced thrust on standing water, and on contaminated or slippery runways



 No reduced thrust with antiskid inop or P MC OFF



 No reduced thrust for windshear, low visibility takeoff 

Reduced Thrust Takeoff  It¶s

safe

OAT

= 30°C weight is MTOW V1

Margin OAT

= 10°C ASS. TEMP = 30°C weight is MTOW

V1

at V1

RTO execution operational margin

Landing and Go-Around



Landing Distance

 A pproach Climb 

Landing Climb



Procedure Design Missed A pproach Gradient

Landing Distance 

JAR

25 defines the landing distance as the horizontal distance required to bring the airplane to a standstill from a point 50 ft above the Runway Threshold.



They are determined for Standard Temperatures as a function of: Weight             Altitude

Wind      

(50% Headwind and 150% Tailwind)

      Configuration (Flaps, Manual/Auto-Speedbrakes, Brakes)



They are determined from a Height of 50 ft at VR EF on a Dry (or  Wet), Smooth Runway using Max Brakes, full Antiskid and Speedbrakes but No Reversers

Landing Distance



Boeing describes the braking technique as ³ Aggressive´. The Brakes are fully depressed at touchdown



Runway Slope is NOT accounted for 



 Non standard temperatures are N OT accounted for 



A pproach

speed

Additives

are NOT accounted for 



These are considered to be covered by the extra margins used to define certified landing distances

Landing Distance

V=

1.23 VS1G

Landing Distance e 60% R unway Length

50 ft

Actual Landing Distance R equired Landing

Dry Factor = 1.67 Distance

Wet Landing Distance = 1.15 x R equired Landing Distance

Wet Factor = 1.15

A pproach Climb

What is A pproach Climb ? 2.1%

A pproach Climb 

Aircrafts

are certified to conduct a missed approach and satisfy a Gradient of  2.1% - GR OSS



The configuration is:

One Engine Inoperative

Gear Up Go Around Flaps (15 on 737) G/A Thrust 

Speed must be e 1.4 VSR 

(Strictly speaking, the Flap Setting must be an intermediate flap setting corresponding to normal procedures whose stalling speed is not more than 110% of the final flap stalling speed)

Landing Climb

What is Landing Climb ?

3.2%

Landing Climb 

Aircrafts

are certified to conduct a missed approach and satisfy a Gradient of  3.2% - GR OSS



The configuration is:

All Engines O perating

Gear Down Landing Flaps (30 or 40 on 737) G/A Thrust 

The speed must be u 1.13 VSR and VMCL



It

is also a requirement that full G/ A thrust must be available within 8 seconds of the thrust levers forward from idle

JAA

Low Visibility Climb



An Aircraft

must be certified to conduct a missed approach and satisfy a Gradient of  2.5% - GR OSS or the published Missed Approach Gradient



The configuration is:

One Engine Inoperative

Gear Up Go Around Flap (15 on a 737) G/A Thrust 

This is only applicable if Low Visibility Procedures will be conducted with a DH of below 200 Ft or No DH

Max

Landing Weight

The maximum landing weight for dispatch is the least of the: Limited Landing Weight



Field



Approach Climb Limited Landing Weight



Landing Climb Limited Landing Weight



JAA



Structural Limited Landing Weight

LVP G/A Climb Gradient Limited Landing Weight

Procedure Missed A pproach Gradient 3.9%

GR OSS

+ 0.6%

MAP

+ 0.8% 98 Ft 2.5%

NET

Procedure Missed A pproach Gradient Some specific procedures require a Net gradient of more than 2.5%. This will be indicated on the Chart

Procedure Missed A pproach Gradient

conflict exists between JAR 25 and ICAO



A



JAR



ICAO



And

25 requires a A pproach Climb Gradient of 2.1% Gross and a Landing Climb gradient of 3.2% Gross requires a missed approach procedure gradient of at least 2.5% Net which may require at least 3.9% Gross Tailwind has not been accounted for 

Procedure Missed A pproach Gradient «but



what if you lose one on t he go-around from a normal approach ?...

The case of an engine failure during Go -Around is not considered as this is deemed a remote possibility!!!

Landing Performance Data Which

is t he more restrictive?

D Fn Both Engines

5x Thrust Available on 1 Engine 75%

EAS



With Twins, the A pproach Climb will be the most limiting

Procedure Missed A pproach Gradient 

Remember the Go -Around procedure is designed for 1 engine inop



With all engines operating, this should not be a problem



With 1 engine inop, generally this should not be a problem



If



the Go Around procedure is very different to EOP  procedure, then it may be prudent to use this procedure Some airfields may specify this if terrain clearance is critical

Factors

affecting landing distance (Typical)