B737-Reduced Thrust Considerations

(1)

Reduced Thrust Considerations

Takeoff Performance Margins

Dick Mayward

Flight Operations Engineering Flight Operations Engineering

Boeing Commercial Airplanes Boeing Commercial Airplanes

May 2004 May 2004

Dick Mayward

Flight Operations Engineering

Boeing Commercial Airplanes

May 2004

(2)

Common Misconceptions

•• “If reduc“If reduced thrused thrust is usedt is used, then th, then the airpe airplane willane will notl not be able to clear the obstacles if an engine fails

be able to clear the obstacles if an engine fails during takeoff.”

during takeoff.”

•• “If the m“If the maximum aximum allowaballowable assumle assumed temed temperature perature isis used, then there will be no stopping margin left if the used, then there will be no stopping margin left if the takeoff is aborted.”

takeoff is aborted.” •

• “If reduced thrust is used, then the airplane will not“If reduced thrust is used, then the airplane will not

be able to clear the obstacles if an engine fails

during takeoff.”

•

• “If the maximum allowable assumed temperature is“If the maximum allowable assumed temperature is

used, then there will be no stopping margin left if the

takeoff is aborted.”

(3)

Common Misconceptions

•• “If reduc“If reduced thrused thrust is usedt is used, then th, then the airpe airplane willane will notl not be able to clear the obstacles if an engine fails

be able to clear the obstacles if an engine fails during takeoff.”

during takeoff.”

•• “If the m“If the maximum aximum allowaballowable assumle assumed temed temperature perature isis used, then there will be no stopping margin left if the used, then there will be no stopping margin left if the takeoff is aborted.”

takeoff is aborted.” •

• “If reduced thrust is used, then the airplane will not“If reduced thrust is used, then the airplane will not

be able to clear the obstacles if an engine fails

during takeoff.”

•

• “If the maximum allowable assumed temperature is“If the maximum allowable assumed temperature is

used, then there will be no stopping margin left if the

takeoff is aborted.”

(4)

Regulatory Compliance

Boeing AFM states: Boeing AFM states:

“Operations at reduced takeoff thrust based on “Operations at reduced takeoff thrust based on

an assumed temperature higher than the actual ambient an assumed temperature higher than the actual ambient temperature is permissible if the airplane meets ALL

temperature is permissible if the airplane meets ALL applicable performance requirements at the planned applicable performance requirements at the planned takeoff weight and reduced thrust setting.”

takeoff weight and reduced thrust setting.” Boeing AFM states:

Boeing AFM states:

“Operations at reduced takeoff thrust based on

an assumed temperature higher than the actual ambient

temperature is permissible if the airplane meets ALL

applicable performance requirements at the planned

takeoff weight and reduced thrust setting.”

AC/AMJ 25-13

(5)

Regulatory Performance Requirements

•• Have sHave sufficufficient rient runwunway lenay length fogth for:r: –

– 115% of al115% of all-engine l-engine takeoff distatakeoff distancence –

– One engOne engine inopine inoperative taerative takeoff distankeoff distancece –

– AccelerateAccelerate-stop dista-stop distancence

•• Achieve thAchieve the one ene one engine inogine inoperative perative minimum minimum climb graclimb gradientdient for:

for: –

– First segmFirst segmentent –

– Second Second segmentsegment –

– Final segFinal segmentment

•• Clear alClear all obstacll obstacles in thes in the intende intended takeoed takeoff flight pff flight pathath •

• Have sufficient runway length for:Have sufficient runway length for:

–

– 115% of all-engine takeoff distance115% of all-engine takeoff distance

–

– One engine inoperative takeoff distanceOne engine inoperative takeoff distance

–

– Accelera Accelerate-stop distate-stop distancence

•

• Achieve Achieve the one ethe one engine inngine inoperative operative minimum minimum climb graclimb gradientdient

for:

–

– First segmentFirst segment

–

– Second segmentSecond segment

–

– Final segmentFinal segment

•

(6)

Effect of Temperature on True

Airspeed and Thrust

Effect of Temperature on True

Airspeed and Thrust

•• Air deAir densitnsity is lower ay is lower at highet higher outsir outside airde air temperature (OAT)

temperature (OAT)

•• For a For a given igiven indicated ndicated airspeed airspeed (IAS), (IAS), truetrue airspeed (TAS) is higher at higher OAT airspeed (TAS) is higher at higher OAT

•• For a For a given regiven reduced duced engine engine power power setting (Nsetting (N11 or EPR), lower air density (higher OAT) results or EPR), lower air density (higher OAT) results in lower thrust

in lower thrust •

• Air density Air density is lower at his lower at higher ouigher outside airtside air

temperature (OAT)

•

• For a given indicated airspeed (IAS), trueFor a given indicated airspeed (IAS), true

airspeed (TAS) is higher at higher OAT

•

• For a given reduced engine power setting (N1For a given reduced engine power setting (N1

or EPR), lower air density (higher OAT) results

in lower thrust

(7)

The Assumed Temperature Method

• Dispatch takeoff performance must assume the higher true airspeed at the assumed higher

temperature

• Takeoff thrust assumed is the rated thrust at that assumed temperature

• Dispatch takeoff performance must assume the higher true airspeed at the assumed higher

temperature

• Takeoff thrust assumed is the rated thrust at that assumed temperature

(8)

Inherent Conservatism

of the Assumed Temperature Method

Inherent Conservatism

of the Assumed Temperature Method

• The actual thrust will be higher than the rated thrust at the assumed temperature, because the actual air density is higher

• The actual true airspeed will be lower, because the actual ambient temperature is lower

• The lower true airspeed combined with the higher thrust will result in a shorter ground distance

• The actual thrust will be higher than the rated thrust at the assumed temperature, because the actual air density is higher

• The actual true airspeed will be lower, because the actual ambient temperature is lower

• The lower true airspeed combined with the higher thrust will result in a shorter ground distance

(9)

The True Airspeed Effect

148 148 146 146 144 144 142 142 140 140 True airspeed, kt True airspeed, kt Assumed temperature, °C Assumed temperature, °C

OAT – assumed temperature difference OAT – assumed temperature difference

Assumed true airspeed Assumed true airspeed

Actual true airspeed at OAT, 15°C Actual true airspeed at OAT, 15°C

30

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7 3 7 -8 0 0 W W IT H C F M 5 6 -7 B 2 7 E N G I N E S P R E S S U R E A L T IT U D E 0 F T R U N W A Y L E N G T H 7 0 0 0 F T , D R Y N O O B S T A C L E S F L A P S 5 , A /C A U T O , S T A N D A R D T A K E O F F S P E E D S M A X I M U M R A T E D T H R U S T (2 7 K ) 2 4 K D E R A T E O A T (C) M T O W ( K G ) P E R F L I M V 1 V R V 2 (KT) M T O W ( K G ) P E R F L I M V 1 V R V 2 (KT) 6 0 6 04 00 F LD 1 34 1 35 1 40 5 59 00 F LD 1 31 1 31 1 34 5 5 6 22 00 F LD 1 36 1 37 1 42 5 77 00 F LD 1 33 1 33 1 37 5 0 6 50 00 F LD 1 38 1 39 1 46 5 97 00 F LD 1 34 1 35 1 39 4 5 6 72 00 F LD 1 40 1 41 1 48 6 19 00 F LD 1 36 1 37 1 42 4 0 6 93 00 F LD 1 41 1 43 1 50 6 41 00 F LD 1 38 1 39 1 44 3 8 7 03 00 F LD 1 42 1 44 1 51 6 50 00 F LD 1 39 1 40 1 45 3 6 7 11 00 F LD 1 42 1 45 1 52 6 58 00 F LD 1 39 1 41 1 46 3 4 7 20 00 F LD 1 43 1 45 1 53 6 67 00 F LD 1 40 1 41 1 47 3 2 7 29 00 F LD 1 43 1 46 1 54 6 77 00 F LD 1 41 1 42 1 48 3 0 7 37 00 F LD 1 44 1 47 1 55 6 86 00 F LD 1 41 1 43 1 49 2 5 7 43 00 F LD 1 44 1 47 1 56 6 92 00 F LD 1 42 1 44 1 50 2 0 7 50 00 F LD 1 45 1 48 1 56 6 98 00 F LD 1 43 1 44 1 51 1 5 7 56 00 F LD 1 46 1 49 1 57 7 03 00 F LD 1 44 1 45 1 51 1 0 7 62 00 F LD 1 46 1 49 1 57 7 10 00 F LD 1 44 1 46 1 52 Maximum Allowable Assumed Temperature 38 C Maximum Allowable Assumed Temperature 38 27K, OAT 15 Takeoff Weight 70300 KG C C 27K, OAT 15 Takeoff Weight 70300 KG

The Assumed Temperature Method

(11)

Margins Between Assumed and Actual Performance

at the Maximum Allowable Assumed Temperature

Margins Between Assumed and Actual Performance

at the Maximum Allowable Assumed Temperature

Parameter V1 (KIAS / KTAS)

VR (KIAS / KTAS) V2 (KIAS / KTAS)

Thrust per engine at V1, lb Thrust per engine at VR, lb Thrust per engine at V2, lb

One engine inoperative takeoff distance, ft Accelerate-stop distance, ft

115% all-engine takeoff distance, ft

OAT 38°C OAT 15 °C assume 38°C Extra margin 142 / 148 144 / 150 151 / 157 23855 19833 19857 7000 7000 6942 142 / 142 144 / 144 151 / 151 24061 20019 20034 6507 6507 6464 6 6 6 206 186 177 493 493 478

(12)

6800 6800 6600 6600 6400 6400 6200 6200 6000 6000 Field length, ft Field length, ft Assumed temperature, °C Assumed temperature, °C Runway length Runway length

Actual balanced field length Actual balanced field length

30

30 3232 3434 3636 3838 4040

Field Length Margin Increases With Lower

Assumed Temperature Due to Higher Thrust

Field Length Margin Increases With Lower

Assumed Temperature Due to Higher Thrust

• 737-800W / CFM56-7B27 • Pressure Altitude 0 ft

• Runway Length 7000 ft, Dry • Flaps 5, Standard Takeoff Speeds • OAT 15°C, Takeoff Weight 70300

kg 7200 7200 7000 7000 28 28

Field Length Margin

875 ft

(13)

25500 25500 25000 25000 24500 24500 24000 24000 23500 23500 Net thrust/ engine at V1, lb Net thrust/ engine at V1, lb Assumed temperature, °C Assumed temperature, °C Rated thrust Rated thrust Actual thrust Actual thrust 30 30 3232 3434 3636 3838 4040

Thrust Margin Decreases

With Lower Assumed Temperature

Thrust Margin Decreases

With Lower Assumed Temperature

26000 26000

28 28

Rated Thrust Versus Actual Thrust

• Runway Length 7000 ft, Dry • Flaps 5, Standard Takeoff Speeds • OAT 15°C, Takeoff Weight 70300

kg

206 lb 206 lb 139 lb

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7 3 7 - 8 00 W W I T H C F M 5 6 - 7 B 2 7 E N G I N E S P R E S S U R E A L T IT U D E 0 F T R U N W A Y L E N G T H 7 0 0 0 F T , D R Y N O O B S T A C L E S F L A P S 5 , A /C A U T O , S T A N D A R D T A K E O F F S P E E D S M A X I M U M R A T E D T H R U S T ( 27 K ) 2 4 K D E R A T E O A T (C) M T O W (KG) P E R F L I M V 1 V R V 2 (KT) M T O W (KG) P E R F LIM V 1 V R V 2 (KT) 6 0 6 04 00 F LD 1 34 1 35 1 40 5 59 00 F LD 1 31 1 31 1 34 5 5 6 22 00 F LD 1 36 1 37 1 42 5 77 00 F LD 1 33 1 33 1 37 5 0 6 50 00 F LD 1 38 1 39 1 46 5 97 00 F LD 1 34 1 35 1 39 4 5 6 72 00 F LD 1 40 1 41 1 48 6 19 00 F LD 1 36 1 37 1 42 4 0 6 93 00 F LD 1 41 1 43 1 50 6 41 00 F LD 1 38 1 39 1 44 3 8 7 03 00 F LD 1 42 1 44 1 51 6 50 00 F LD 1 39 1 40 1 45 3 6 7 11 00 F LD 1 42 1 45 1 52 6 58 00 F LD 1 39 1 41 1 46 3 4 7 20 00 F LD 1 43 1 45 1 53 6 67 00 F LD 1 40 1 41 1 47 3 2 7 29 00 F LD 1 43 1 46 1 54 6 77 00 F LD 1 41 1 42 1 48 3 0 7 37 00 F LD 1 44 1 47 1 55 6 86 00 F LD 1 41 1 43 1 49 2 5 7 43 00 F LD 1 44 1 47 1 56 6 92 00 F LD 1 42 1 44 1 50 2 0 7 50 00 F LD 1 45 1 48 1 56 6 98 00 F LD 1 43 1 44 1 51 1 5 7 56 00 F LD 1 46 1 49 1 57 7 03 00 F LD 1 44 1 45 1 51 1 0 7 62 00 F LD 1 46 1 49 1 57 7 10 00 F LD 1 44 1 46 1 52

Lower Takeoff Weight May Permit Higher

Maximum Allowable Assumed Temperature

Lower Takeoff Weight May Permit Higher

Maximum Allowable Assumed Temperature

(15)

145 145 140 140 135 135 130 130 True airspeed, kt True airspeed, kt Assumed temperature, °C Assumed temperature, °C

Assumed true airspeed Assumed true airspeed

Actual true airspeed at OAT Actual true airspeed at OAT

40

40 4545 5050 5555 6060 6565

True Airspeed Effect Increases

With Higher Assumed Temperature

True Airspeed Effect Increases

With Higher Assumed Temperature

150 150 35 35 6 kt 10 kt

True Airspeed Effect

(16)

22000 22000 21000 21000 20000 20000 19000 19000 18000 18000 Net thrust/ engine at V1, lb Net thrust/ engine at V1, lb Assumed temperature, °C Assumed temperature, °C Rated thrust Rated thrust Actual thrust Actual thrust 40 40 4545 5050 5555 6060 6565

Thrust Margin Increases

With Higher Assumed Temperature

Thrust Margin Increases

With Higher Assumed Temperature

23000 23000 35 35 650 lb 650 lb • 737-800W / CFM56-7B27

• Pressure Altitude 0 ft, OAT 15°C

• Runway Length 7000 ft, Dry • Flaps 5, Standard Takeoff

Speeds 206 lb 206 lb 24000 24000 25000 25000

Rated Thrust Versus Actual Thrust

(17)

• 737-800W / CFM56-7B27

• Runway Length 7000 ft, Dry • Flaps 5, Standard Takeoff

Speeds 6600 6600 6400 6400 6200 6200 6000 6000 5800 5800 Field length, ft Field length, ft Assumed temperature, °C Assumed temperature, °C Runway length Runway length

Actual balanced field length Actual balanced field length

40

40 4545 5050 5555 6060 6565

Field Length Margin Due to the True Airspeed Effect

Increases With Higher Assumed Temperature

Field Length Margin Due to the True Airspeed Effect

Increases With Higher Assumed Temperature

6800 6800 35 35 493 ft 1035 ft 7200 7200 7000 7000

Field Length Margin

(18)

• If performance is limited by the one engine inoperative minimum climb gradient requirements, the higher

actual thrust will result in a higher climb gradient • If performance is limited by obstacle clearance,

the higher climb gradient combined with the shorter takeoff distance will result in extra clearance margin • If performance is limited by the one engine inoperative

minimum climb gradient requirements, the higher actual thrust will result in a higher climb gradient • If performance is limited by obstacle clearance,

the higher climb gradient combined with the shorter takeoff distance will result in extra clearance margin

Extra obstacle clearance margins

Performance Margins in Flight Path With

Assumed Temperature Reduced Thrust

Performance Margins in Flight Path With

Assumed Temperature Reduced Thrust

A c t u a l t h r u s t a n d c l i m b g r a d i e n t R a t e d t h r u s t a t t h e a s s u m e d t e m p

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7 3 7 -8 0 0W W IT H C F M 5 6 -7 B 2 7 E N G I N E S P R E S S U R E A L T IT U D E 5 0 0 0 F T R U N W A Y L E N G T H 1 2 0 0 0 F T , D R Y N O O B S T A C L E S F L A P S 5 , A /C A U T O , S T A N D A R D T A K E O F F S P E E D S M A X I M U M R A T E D T H R U S T (2 7 K ) 2 4 K D E R A T E O A T (C) M T O W ( KG ) P E R F L I M V 1 V R V 2 ( KT ) M T O W ( KG ) P E R F L I M V 1 V R V 2 ( KT ) 6 0 5 73 00 C L B 1 33 1 33 1 36 4 93 00 C LB 1 24 1 24 1 26 5 5 5 99 00 C L B 1 36 1 36 1 39 5 15 00 C LB 1 26 1 26 1 29 5 0 6 25 00 C L B 1 38 1 39 1 42 5 38 00 C LB 1 29 1 29 1 32 4 5 6 51 00 C L B 1 41 1 41 1 45 5 62 00 C LB 1 32 1 32 1 34 4 0 6 81 00 C L B 1 43 1 44 1 48 5 89 00 C LB 1 35 1 35 1 38 3 5 7 10 00 C L B 1 46 1 47 1 51 6 17 00 C LB 1 38 1 38 1 41 3 0 7 39 00 C L B 1 48 1 50 1 54 6 46 00 C LB 1 40 1 41 1 44 2 5 7 54 00 C L B 1 49 1 51 1 55 6 76 00 C LB 1 43 1 44 1 47 2 0 7 64 00 C L B 1 50 1 52 1 56 7 08 00 C LB 1 46 1 47 1 51 1 5 7 64 00 C L B 1 50 1 52 1 56 7 09 00 C LB 1 46 1 47 1 51 1 0 7 65 00 C L B 1 50 1 52 1 56 7 10 00 C LB 1 46 1 47 1 51 27K, OAT 10 Takeoff Weight 71000 KG C 27K, OAT 10 Takeoff Weight 71000 KG Maximum Allowable Assumed Temperature 35 C C Maximum Allowable Assumed Temperature 35

Thrust And Climb Gradient Margins At The

Maximum Allowable Assumed Temperature

Thrust And Climb Gradient Margins At The

Maximum Allowable Assumed Temperature

Parameter Thrust per engine at V2, lb

One engine inoperative climb gradient, %

OAT 35°C OAT 10 °C assume 35°C Extra margin 20108 2.4 20355 2.54 247 0.14 C

(20)

• 737-800W / CFM56-7B27 • Pressure Altitude 5000 ft • Runway Length 12000 ft, Dry • Flaps 5, Standard Takeoff Speeds • OAT 10°C, Takeoff Weight 71000 kg

2.8 2.8 2.6 2.6 2.4 2.4 2.2 2.2 Climb gradient , % Climb gradient , % Assumed temperature, °C Assumed temperature, °C Regulatory minimum Regulatory minimum Actual gradient Actual gradient 20 20 2525 3030 3535 4040 3.0 3.0 15 15 3.4 3.4 3.2 3.2

Climb Gradient Increases With Lower

Assumed Temperature Due to Higher Thrust

Climb Gradient Increases With Lower

Assumed Temperature Due to Higher Thrust

0.9 %

Climb Gradient Margin

(21)

7 3 7 -8 0 0W W IT H C F M 5 6 -7 B 2 7 E N G I N E S P R E S S U R E A L T IT U D E 5 0 0 0 F T R U N W A Y L E N G T H 1 2 0 0 0 F T , D R Y N O O B S T A C L E S F L A P S 5 , A /C A U T O , S T A N D A R D T A K E O F F S P E E D S M A X I M U M R A T E D T H R U S T ( 27 K ) 2 4 K D E R A T E O A T (C) M T O W ( K G ) P E R F L I M V 1 V R V 2 ( KT ) M T O W ( K G ) P E R F L I M V 1 V R V 2 ( KT ) 6 0 5 73 00 C L B 1 33 1 33 1 36 4 93 00 C LB 1 24 1 24 1 26 5 5 5 99 00 C L B 1 36 1 36 1 39 5 15 00 C LB 1 26 1 26 1 29 5 0 6 25 00 C L B 1 38 1 39 1 42 5 38 00 C LB 1 29 1 29 1 32 4 5 6 51 00 C L B 1 41 1 41 1 45 5 62 00 C LB 1 32 1 32 1 34 4 0 6 81 00 C L B 1 43 1 44 1 48 5 89 00 C LB 1 35 1 35 1 38 3 5 7 10 00 C L B 1 46 1 47 1 51 6 17 00 C LB 1 38 1 38 1 41 3 0 7 39 00 C L B 1 48 1 50 1 54 6 46 00 C LB 1 40 1 41 1 44 2 5 7 54 00 C L B 1 49 1 51 1 55 6 76 00 C LB 1 43 1 44 1 47 2 0 7 64 00 C L B 1 50 1 52 1 56 7 08 00 C LB 1 46 1 47 1 51 1 5 7 64 00 C L B 1 50 1 52 1 56 7 09 00 C LB 1 46 1 47 1 51 1 0 7 65 00 C L B 1 50 1 52 1 56 7 10 00 C LB 1 46 1 47 1 51

Lower Takeoff Weight May Permit A Higher

Maximum Allowable Assumed Temperature

Lower Takeoff Weight May Permit A Higher

(22)

• 737-800W / CFM56-7B27

• Runway Length 12000 ft, Dry • Flaps 5, Standard Takeoff Speeds

Climb gradient , % Climb gradient , % Assumed temperature, °C Assumed temperature, °C 35 35 4040 4545 5050 5555 30 30

Climb Gradient Margin Due to the True Airspeed

Effect Increases With Higher Assumed Temperature

Climb Gradient Margin Due to the True Airspeed

Effect Increases With Higher Assumed Temperature

60 60 6565 2.6 2.6 2.4 2.4 Regulatory minimum Regulatory minimum Actual gradient Actual gradient 0.25 % 0.14 % 2.3 2.3 2.5 2.5 2.7 2.7

Climb Gradient Margin

(23)

737-800W W ITH CFM56-7B27 ENGINES PRESSURE ALTITUDE 0 FT

RUNW AY 9000 FT, DRY

OBSTACLE: 50 FT HT AT 1000 FT DIST FROM LIFTOFF END FLAPS 5, A/C AUTO, STANDARD TAKEO FF SPEEDS

MAXIMUM RATED THRUST (27K) 24K DERATE

OAT (C) MTOW (KG) PERF LIM V1 VR V2 (KT) M T O W (KG) PERF LIM V1 VR V2 (KT) 6 0 6 29 00 O B S 1 38 1 38 1 43 5 70 00 O B S 1 32 1 32 1 36 5 5 6 52 00 O B S 1 40 1 41 1 45 5 92 00 O B S 1 34 1 34 1 38 5 0 6 86 00 O B S 1 42 1 44 1 49 6 16 00 O B S 1 37 1 37 1 41 4 5 7 13 00 O B S 1 44 1 46 1 52 6 42 00 O B S 1 39 1 40 1 44 4 3 7 24 00 O B S 1 45 1 47 1 53 6 52 00 O B S 1 40 1 41 1 45 4 1 7 35 00 O B S 1 46 1 48 1 54 6 63 00 O B S 1 41 1 42 1 46 3 9 7 46 00 O B S 1 47 1 49 1 55 6 74 00 O B S 1 42 1 43 1 48 3 7 7 57 00 O B S 1 47 1 50 1 56 6 84 00 O B S 1 43 1 44 1 49 3 5 7 67 00 O B S 1 48 1 51 1 57 6 94 00 O B S 1 43 1 45 1 50 3 0 7 93 00 O B S 1 49 1 53 1 60 7 22 00 O B S 1 46 1 47 1 53 2 5 7 98 00 O B S 1 50 1 53 1 60 7 27 00 O B S 1 46 1 47 1 53 2 0 8 03 00 O B S 1 50 1 54 1 61 7 31 00 O B S 1 47 1 48 1 53 1 5 8 08 00 O B S 1 51 1 54 1 61 7 35 00 O B S 1 47 1 48 1 54 1 0 8 13 00 O B S 1 51 1 55 1 61 7 39 00 O B S 1 47 1 49 1 54 Maximum Allowable Assumed Temperature 41 C Maximum Allowable Assumed Temperature 41 27K, OAT 15 Takeoff Weight 73500 KG C C 27K, OAT 15 Takeoff Weight 73500 KG

Obstacle Clearance Margin at the Maximum

Allowable Assumed Temperature

Obstacle Clearance Margin at the Maximum

Allowable Assumed Temperature

Parameter Net clearance OAT 41°C OAT 15 °C assume 41°C Extra margin 35 ft 61 ft 26 ft C

(24)

• Runway Length 9000 ft, Dry

• Obstacle: 50 ft Ht at 1000 ft Dist from liftoff end • Flaps 5, Standard Takeoff Speeds

• OAT 15°C, Takeoff Weight 73500 kg

80 80 60 60 40 40 20 20 Net clearance, ft Net clearance, ft Assumed temperature, °C Assumed temperature, °C Regulatory minimum Regulatory minimum

Actual net clearance Actual net clearance

30 30 3232 3434 3636 3838 100 100 28 28 120 120

Obstacle Clearance Margin

Net Clearance Margin Increases With Lower

Assumed Temperature Due to Higher Thrust

Net Clearance Margin Increases With Lower

Assumed Temperature Due to Higher Thrust

26 ft 81 ft

40

(25)

737-800W W ITH CFM56-7B27 ENGINES PRESSURE ALTITUDE 0 FT

RUNWAY 9000 FT, DRY

OBST ACLE: 50 FT HT AT 1000 FT DIST FROM LIFTOFF END FLAPS 5, A/C AUTO, STANDARD TAKEOFF SPEEDS MAXIMUM RATED THRUST (27K) 24K DERATE OAT (C) MTOW (KG) PERF LIM V1 VR V2 (KT) MTOW (KG) PERF LIM V1 VR V2 (KT) 60 62900 OBS 138 138 143 57000 OBS 132 132 136 55 65200 OBS 140 141 145 59200 OBS 134 134 138 50 68600 OBS 142 144 149 61600 OBS 137 137 141 45 71300 OBS 144 146 152 64200 OBS 139 140 144 43 72400 OBS 145 147 153 65200 OBS 140 141 145 41 73500 OBS 146 148 154 66300 OBS 141 142 146 39 74600 OBS 147 149 155 67400 OBS 142 143 148 37 75700 OBS 147 150 156 68400 OBS 143 144 149 35 76700 OBS 148 151 157 69400 OBS 143 145 150 30 79300 OBS 149 153 160 72200 OBS 146 147 153 25 79800 OBS 150 153 160 72700 OBS 146 147 153 20 80300 OBS 150 154 161 73100 OBS 147 148 153 15 80800 OBS 151 154 161 73500 OBS 147 148 154 10 81300 OBS 151 155 161 73900 OBS 147 149 154

Lower Takeoff Weight May Permit Higher

Maximum Allowable Assumed Temperature

Lower Takeoff Weight May Permit Higher

Maximum Allowable Assumed Temperature

(26)

• 737-800W / CFM56-7B27

• Obstacle: 50 ft Ht at 1000 ft Dist from liftoff end

• Flaps 5, Standard Takeoff Speeds

60 60 40 40 20 20 Net clearance, ft Net clearance, ft Assumed temperature, °C Assumed temperature, °C Regulatory minimum Regulatory minimum Actual net clearance Actual net clearance

45 45 5050 5555 6060 40 40 80 80

Obstacle Clearance Margin

65 65

Net Clearance Margin Due to True Airspeed Effect

Increases With Higher Assumed Temperature

Net Clearance Margin Due to True Airspeed Effect

Increases With Higher Assumed Temperature

58 ft

(27)

Issues With Takeoff Speeds

• Standard takeoff speeds depend on: – Takeoff weight

– Flap setting

– Thrust (temperature, pressure altitude, and engine bleed configuration)

– V1 also depends on runway slope, wind, and surface condition (dry or wet)

• Takeoff speeds vary with thrust, therefore, they vary with assumed temperature

• Standard takeoff speeds depend on: – Takeoff weight

– Flap setting

– Thrust (temperature, pressure altitude, and engine bleed configuration)

– V1 also depends on runway slope, wind, and surface condition (dry or wet)

• Takeoff speeds vary with thrust, therefore, they vary with assumed temperature

(28)

Increasing V1 and VR, typically resulting in lower V2, will re-balance field length

V1 = 140 VR = 145 V2 = 150

Lower thrust

Proper takeoff speeds for a balanced field length

V2 = 155

Higher thrust

V1 = 135 VR = 140

Effect of Thrust on Takeoff Speeds (IAS)

(29)

• Flaps 5, Dry Runway, Standard Speeds

• OAT 15°C, Takeoff Weight 60400 kg

140 140 135 135 130 130 125 125 Takeoff speeds, KIAS Takeoff speeds, KIAS Assumed temperature, °C Assumed temperature, °C V1 V1 VR VR 30 30 3535 4040 4545 5050 25 25 145 145

Thrust Effect on Takeoff Speeds

55

55 6060

Takeoff Speeds (IAS) Vary

With Assumed Temperature

Takeoff Speeds (IAS) Vary

With Assumed Temperature

V2 V2

65 65

(30)

Use the FMC or QRH to Obtain

Proper Standard Takeoff Speeds

Use the FMC or QRH to Obtain

Proper Standard Takeoff Speeds

T A K E O F F R E F 1 / 2 F L A P S ° 2 6 K N 1 9 8 . 8 / 9 8 . 8 % C G T R I M 22.5% 5 . 2 5 R U N W A Y < P E R F I N I T Q R H V 1 V R V 2 G W / T O W S E L E C T QRH OFF> — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — —

Standard Takeoff Speeds Only

Standard takeoff speeds, plus adjustments for clearway and stopway, slippery and contaminated runways, and inoperative system. No optimized V1 or improved climb.

Q u i c k R e f e r e n

c e H a n d b o

(31)

7 3 7 -8 0 0W W IT H C F M 5 6 - 7B 2 7 E N G IN E S P R E S S U R E A L T IT U D E 0 F T R U N W A Y L E N G T H 7 0 0 0 F T , D R Y N O O B S T A C L E S F L A P S 5 , A /C A U T O , S T A N D A R D T A K E O F F S P E E D S M A X I M U M R A T E D T H R U S T (2 7 K ) 2 4 K D E R A T E O A T (C) M T O W (KG) P E R F L I M V 1 V R V 2 (KT) M T O W (KG) P E R F L I M V 1 V R V 2 (KT) 6 0 6 04 00 F LD 1 34 1 35 1 40 5 59 00 F LD 1 31 1 31 1 34 5 5 6 22 00 F LD 1 36 1 37 1 42 5 77 00 F LD 1 33 1 33 1 37 5 0 6 50 00 F LD 1 38 1 39 1 46 5 97 00 F LD 1 34 1 35 1 39 4 5 6 72 00 F LD 1 40 1 41 1 48 6 19 00 F LD 1 36 1 37 1 42 4 0 6 93 00 F LD 1 41 1 43 1 50 6 41 00 F LD 1 38 1 39 1 44 3 8 7 03 00 F LD 1 42 1 44 1 51 6 50 00 F LD 1 39 1 40 1 45 3 6 7 11 00 F LD 1 42 1 45 1 52 6 58 00 F LD 1 39 1 41 1 46 3 4 7 20 00 F LD 1 43 1 45 1 53 6 67 00 F LD 1 40 1 41 1 47 3 2 7 29 00 F LD 1 43 1 46 1 54 6 77 00 F LD 1 41 1 42 1 48 3 0 7 37 00 F LD 1 44 1 47 1 55 6 86 00 F LD 1 41 1 43 1 49 2 5 7 43 00 F LD 1 44 1 47 1 56 6 92 00 F LD 1 42 1 44 1 50 2 0 7 50 00 F LD 1 45 1 48 1 56 6 98 00 F LD 1 43 1 44 1 51 1 5 7 56 00 F LD 1 46 1 49 1 57 7 03 00 F LD 1 44 1 45 1 51 1 0 7 62 00 F LD 1 46 1 49 1 57 7 10 00 F LD 1 44 1 46 1 52 27K, OAT 15 Takeoff Weight 60400 KG C 27K, OAT 15 Takeoff Weight 60400 KG Maximum Allowable Assumed Temperature 60 C C Maximum Allowable Assumed Temperature 60

Overspeed

Use Speeds for the Maximum Allowable Assumed

Temperature, Ignoring Thrust Effect on Speeds

Use Speeds for the Maximum Allowable Assumed

Temperature, Ignoring Thrust Effect on Speeds

(32)

737-800W / CFM56-7B27 Pressure Altitude 0 ft, OAT 15°C

Dry Runway, Standard Speeds Flaps 5, Takeoff Weight 60400 kg

128 / 131 / 143 15°C 131 / 133 / 142 45°C 134 / 135 / 140 60°C V1 / VR / V2 (kt) Assumed temperature

Proper Takeoff Speeds From QRH

(33)

7 3 7 -8 0 0W W IT H C F M 5 6 -7 B 2 7 E N G I N E S P R E S S U R E A L T IT U D E 0 F T R U N W A Y L E N G T H 7 0 0 0 FT , D R Y N O O B S T A C L E S F L A P S 5 , A /C A U T O , S T A N D A R D T A K E O F F S P E E D S M A X I M U M R A T E D T H R U S T ( 27 K ) 2 4 K D E R A T E O A T (C) M T O W (KG) P E R F L I M V 1 V R V 2 (KT) M T O W (KG) P E R F L I M V 1 V R V 2 (KT) 6 0 6 04 00 F LD 1 34 1 35 1 40 5 5 90 0 F L D 1 31 1 31 1 34 5 5 6 22 00 F LD 1 36 1 37 1 42 5 7 70 0 F L D 1 33 1 33 1 37 5 0 6 50 00 F LD 1 38 1 39 1 46 5 9 70 0 F L D 1 34 1 35 1 39 4 5 6 72 00 F LD 1 40 1 41 1 48 6 1 90 0 F L D 1 36 1 37 1 42 4 0 6 93 00 F LD 1 41 1 43 1 50 6 4 10 0 F L D 1 38 1 39 1 44 3 8 7 03 00 F LD 1 42 1 44 1 51 6 5 00 0 F L D 1 39 1 40 1 45 3 6 7 11 00 F LD 1 42 1 45 1 52 6 5 80 0 F L D 1 39 1 41 1 46 3 4 7 20 00 F LD 1 43 1 45 1 53 6 6 70 0 F L D 1 40 1 41 1 47 3 2 7 29 00 F LD 1 43 1 46 1 54 6 7 70 0 F L D 1 41 1 42 1 48 3 0 7 37 00 F LD 1 44 1 47 1 55 6 8 60 0 F L D 1 41 1 43 1 49 2 5 7 43 00 F LD 1 44 1 47 1 56 6 9 20 0 F L D 1 42 1 44 1 50 2 0 7 50 00 F LD 1 45 1 48 1 56 6 9 80 0 F L D 1 43 1 44 1 51 1 5 7 56 00 F LD 1 46 1 49 1 57 7 0 30 0 F L D 1 44 1 45 1 51 1 0 7 62 00 F LD 1 46 1 49 1 57 7 1 00 0 F L D 1 44 1 46 1 52 27K, OAT 15 Takeoff Weight 60400 KG C 27K, OAT 15 Takeoff Weight 60400 KG Maximum Allowable Assumed Temperature 60 C C Maximum Allowable Assumed Temperature 60

Overspeed

Use Speeds for the Lower Assumed Temperature,

Ignoring Weight Effect on Speeds

Use Speeds for the Lower Assumed Temperature,

Ignoring Weight Effect on Speeds

(34)

6000 6000 6200 6200 6400 6400 6600 6600 6800 6800 7000 7000 7200 7200 28 28 3030 3232 3434 3636 3838 4040 • 737-800W / CFM56-7B27

• Runway Length 7000 ft, Dry • Flaps 5, Takeoff Weight 70300 kg • Max Allowable Assumed Temp

38°C Field length, ft Field length, ft

Field Length Margin With Overspeed

Overspeed Reduces Field Length Margin

Proper speeds Runway length available

Overspeed – Max assumed temp Overspeed – Lower assumed temp Assumed temperature, °C Assumed temperature, °C

(35)

• 737-800W / CFM56-7B27 • Pressure Altitude 5000 ft, OAT

10°C

• Runway Length 12000 ft, Dry • Flaps 5, Takeoff Weight 71000 kg • Max Allowable Assumed Temp

35°C Climb gradient, % Climb gradient, %

Climb Gradient Margin With Overspeed

Proper speeds

Regulatory minimum

Effect of Overspeed on Climb Gradient

2.2 2.2 2.4 2.4 2.6 2.6 2.8 2.8 3.0 3.0 3.2 3.2 3.4 3.4 3.6 3.6 15 15 2020 2525 3030 3535 4040 Assumed temperature, °C Assumed temperature, °C Overspeed

– Lower assumed temp

Overspeed

(36)

• 737-800W / CFM56-7B27

• Obstacle: 50 ft Ht at 1000 ft Dist from liftoff end

• Flaps 5, Takeoff Weight 73500 kg • Max Allowable Assumed Temp 41°C

Net clearance , ft Net clearance , ft Assumed temperature, °C Assumed temperature, °C

Obstacle Clearance With Overspeed

Overspeed Reduces

Obstacle Clearance Margin

Overspeed Reduces

Obstacle Clearance Margin

20 20 40 40 60 60 80 80 100 100 120 120 28 28 3030 3232 3434 3636 3838 4040 4242 Proper speeds Regulatory minimum Overspeed – Max assumed temp Overspeed – Lower assumed temp

(37)

Means to Maximize Thrust Reduction

and Performance Margins

Means to Maximize Thrust Reduction

and Performance Margins

• Takeoff configuration: – Flaps setting selection

– No engine bleed for A/C packs • Takeoff speeds options:

– Improved climb

– Optimized V1 (unbalanced)

• Goal: Increase the difference between the OAT and the assumed temperature, thus increasing the true airspeed effect.

• Takeoff configuration: – Flaps setting selection

– No engine bleed for A/C packs • Takeoff speeds options:

– Improved climb

– Optimized V1 (unbalanced)

• Goal: Increase the difference between the OAT and the assumed temperature, thus increasing the true airspeed effect.

(38)

7 3 7 -8 0 0 W W IT H C F M 5 6 -7 B 2 7 E N G IN E S P R E S S U R E A L T IT U D E 0 F T R U N W A Y L E N G T H 7 0 0 0 F T , D R Y N O O B S T A C L E S 2 7 K , S T A N D A R D T A K E O F F S P E E D S O A T ( C ) F L A P S 5 A /C A U T O F L A P S 1 5 A /C A U T O F L A P S 5 A /C O F F 6 0 6 0 4 0 0 6 0 8 0 0 6 1 3 0 0 5 5 6 2 2 0 0 6 3 4 0 0 6 3 2 0 0 5 0 6 5 0 0 0 6 6 1 0 0 6 6 0 0 0 4 5 6 7 2 0 0 6 8 2 0 0 6 8 1 0 0 4 0 6 9 3 0 0 7 0 5 0 0 7 0 3 0 0 3 8 7 0 3 0 0 7 1 4 0 0 7 1 1 0 0 3 6 7 1 1 0 0 7 2 3 0 0 7 2 0 0 0 3 4 7 2 0 0 0 7 3 2 0 0 7 2 8 0 0 3 2 7 2 9 0 0 7 4 1 0 0 7 3 6 0 0 3 0 7 3 7 0 0 7 5 0 0 0 7 4 4 0 0 2 5 7 4 3 0 0 7 5 7 0 0 7 5 0 0 0 2 0 7 5 0 0 0 7 6 3 0 0 7 5 6 0 0 1 5 7 5 6 0 0 7 6 9 0 0 7 6 2 0 0 1 0 7 6 2 0 0 7 7 6 0 0 7 6 9 0 0

Means to Maximize Thrust

Reduction and Margin

Means to Maximize Thrust

Reduction and Margin

OAT 15

Takeoff Weight 70300 KG C

OAT 15

Takeoff Weight 70300 KG

Performance Limited by Field Length

(39)

Assumed temperature 38°C 38°C 38°C 40°C 40°C Field length required, ft Extra margin, ft 6507 6314 6360 6416 6461 493 686 640 584 539

Field Length Margin

With Optimum Takeoff Configuration

Field Length Margin

With Optimum Takeoff Configuration

Takeoff configuration Flaps 5, A/C Auto Flaps 15, A/C Auto Flaps 5, A/C Off Flaps 15, A/C Auto Flaps 5, A/C Off

(40)

7 3 7 -8 0 0 W W IT H C F M 5 6 -7 B 2 7 E N G I N E S P R E S S U R E A L T IT U D E 5 0 0 0 F T R U N W A Y L E N G T H 1 2 0 0 0 F T , D R Y N O O B S T A C L E S 2 7 K , A /C A U T O O A T ( C ) F L A P S 5 N O IM P C L B F L A P S 1 N O IM P C L B F L A P S 5 W IT H I M P C L B 6 0 5 7 3 0 0 5 9 3 0 0 6 0 6 0 0 5 5 5 9 9 0 0 6 2 0 0 0 6 3 2 0 0 5 0 6 2 5 0 0 6 4 7 0 0 6 5 7 0 0 4 5 6 5 1 0 0 6 7 4 0 0 6 8 3 0 0 4 0 6 8 1 0 0 7 0 5 0 0 7 1 1 0 0 3 9 6 8 7 0 0 7 1 1 0 0 7 1 6 0 0 3 7 6 9 9 0 0 7 2 4 0 0 7 2 5 0 0 3 5 7 1 0 0 0 7 3 1 0 0 7 3 4 0 0 3 0 7 3 9 0 0 7 4 0 0 0 7 5 3 0 0 2 5 7 5 4 0 0 7 4 8 0 0 7 6 5 0 0 2 0 7 6 4 0 0 7 5 5 0 0 7 7 3 0 0 1 5 7 6 4 0 0 7 6 1 0 0 7 7 7 0 0 1 0 7 6 5 0 0 7 6 8 0 0 7 8 1 0 0

Means to Maximize

Thrust Reduction and Margin

Means to Maximize

Thrust Reduction and Margin

OAT 10

Takeoff Weight 71000 KG C

OAT 10

Takeoff Weight 71000 KG

Performance Limited by Climb or Obstacle Clearance

(41)

Performance Margins

With Optimum Takeoff Option

Performance Margins

With Optimum Takeoff Option

Assumed temperature 35°C 35°C 39°C 40°C Field length required, ft Extra margin, ft 9086 9804 10153 10642 2914 2196 1847 1358 Takeoff option

Flaps 5, No Imp Climb Flaps 1, No Imp Climb Flaps 1, No Imp Climb Flaps 5, Improved Climb

Climb gradient, % 2.54 2.93 2.58 2.58

(42)

The Takeoff Derate Method

• Available for use on slippery or contaminated runways and with inoperative antiskid

• Can be combined with use of assumed temperature • Available for use on slippery or contaminated runways

and with inoperative antiskid

(43)

7 3 7 -8 0 0W W IT H C F M 5 6 -7 B 2 7 E N G I N E S P R E S S U R E A L T IT U D E 0 F T R U N W A Y L E N G T H 7 0 0 0 FT , D R Y N O O B S T A C LE S F L A P S 5 , A /C A U T O , S T A N D A R D T A K E O F F S P E E D S M A X I M U M R A T E D T H R U S T (2 7 K ) 2 4 K D E R A T E O A T (C) M T O W ( K G ) P E R F L I M V 1 V R V 2 (KT) M T O W ( K G ) P E R F L I M V 1 V R V 2 (KT) 6 0 6 04 00 F LD 1 34 1 35 1 40 5 59 00 F LD 1 31 1 31 1 34 5 5 6 22 00 F LD 1 36 1 37 1 42 5 77 00 F LD 1 33 1 33 1 37 5 0 6 50 00 F LD 1 38 1 39 1 46 5 97 00 F LD 1 34 1 35 1 39 4 5 6 72 00 F LD 1 40 1 41 1 48 6 19 00 F LD 1 36 1 37 1 42 4 0 6 93 00 F LD 1 41 1 43 1 50 6 41 00 F LD 1 38 1 39 1 44 3 8 7 03 00 F LD 1 42 1 44 1 51 6 50 00 F LD 1 39 1 40 1 45 3 6 7 11 00 F LD 1 42 1 45 1 52 6 58 00 F LD 1 39 1 41 1 46 3 4 7 20 00 F LD 1 43 1 45 1 53 6 67 00 F LD 1 40 1 41 1 47 3 2 7 29 00 F LD 1 43 1 46 1 54 6 77 00 F LD 1 41 1 42 1 48 3 0 7 37 00 F LD 1 44 1 47 1 55 6 86 00 F LD 1 41 1 43 1 49 2 5 7 43 00 F LD 1 44 1 47 1 56 6 92 00 F LD 1 42 1 44 1 50 2 0 7 50 00 F LD 1 45 1 48 1 56 6 98 00 F LD 1 43 1 44 1 51 1 5 7 56 00 F LD 1 46 1 49 1 57 7 03 00 F LD 1 44 1 45 1 51 1 0 7 62 00 F LD 1 46 1 49 1 57 7 10 00 F LD 1 44 1 46 1 52

Runway Length Consideration

OAT 15 Takeoff Weight 70300 KG C OAT 15 Takeoff Weight 70300 KG C

(44)

24K Derate OAT 15°C 27K assume 38°C 7000 22353 93.8 6507 24061 97.2 Parameter

Field Length Required, ft Thrust per Engine at V1, lb Takeoff N1 Setting

Using Derate

Reduces Performance Margins

Using Derate

(45)

737-800W WITH CFM56-7B27 ENGINES PRESSURE ALTITUDE 5000 FT RUNWAY LENGTH 12000 FT, DRY

NO OBSTACLES

FLAPS 5, A/C AUTO, STANDARD TAKEOFF SPEEDS MAXIMUM RATED THRUST (27K) 24K DERATE OAT (C) MTOW (KG) PERF LIM V1 VR V2 (KT) MTOW (KG) PERF LIM V1 VR V2 (KT) 60 57300 CLB 133 133 136 49300 CLB 124 124 126 55 59900 CLB 136 136 139 51500 CLB 126 126 129 50 62500 CLB 138 139 142 53800 CLB 129 129 132 45 65100 CLB 140 141 145 56200 CLB 132 132 134 40 68100 CLB 141 141 148 58900 CLB 135 135 138 35 71000 CLB 146 147 151 61700 CLB 138 138 141 30 73900 CLB 148 150 154 64600 CLB 140 141 144 25 75400 CLB 149 151 155 67600 CLB 143 144 147 20 76400 CLB 150 152 156 70800 CLB 146 147 151 15 76400 CLB 150 152 156 70900 CLB 146 147 151 10 76500 CLB 150 152 156 71000 CLB 146 147 151

Climb Consideration

(46)

24K Derate OAT 10°C 27K assume 35°C 2.4 2.54 Parameter One Engine Inoperative Climb Gradient (%)

Using Derate

Reduces Performance Margins

Using Derate

(47)

737-800W WITH CFM56-7B27 ENGINES PRESSURE ALTITUDE 0 FT

RUNWAY LENGTH 9000 FT, DRY

OBSTACLE: 50 FT HT AT 1000 FT DIST FROM LIFTOFF END FLAPS 5, A/C AUTO, STANDARD TAKEOFF SPEEDS MAXIMUM RATED THRUST (27K) 24K DERATE OAT (C) MTOW (KG) PERF LIM V1 VR V2 (KT) MTOW (KG) PERF LIM V1 VR V2 (KT) 60 62900 OBS 138 138 143 57000 OBS 132 132 136 55 65200 OBS 140 141 145 59200 OBS 134 134 138 50 68600 OBS 142 144 149 61600 OBS 137 137 141 45 71300 OBS 144 146 152 64200 OBS 139 140 144 43 72400 OBS 145 147 153 65200 OBS 140 141 145 41 73500 OBS 146 148 154 66300 OBS 141 142 146 39 74600 OBS 147 149 155 67400 OBS 142 143 148 37 75700 OBS 147 150 156 68400 OBS 143 144 149 35 76700 OBS 148 151 157 69400 OBS 143 145 150 30 79300 OBS 149 153 160 72200 OBS 146 147 153 25 79800 OBS 150 153 160 72700 OBS 146 147 153 20 80300 OBS 150 154 161 73100 OBS 147 148 153 15 80800 OBS 151 154 161 73500 OBS 147 148 154 10 81300 OBS 151 155 161 73900 OBS 147 149 154

Obstacle Clearance Consideration

(48)

Using Derate Reduces

Performance Margins

Using Derate Reduces

Performance Margins

24K Derate OAT 15°C 27K assume 41°C 35 61 Parameter Net Clearance (ft)

(49)

98 98 96 96 94 94 93 93 N1 N1 OAT, °C OAT, °C

27K and max allowable assumed temp 27K and max allowable assumed temp

24K Derate at OAT 24K Derate at OAT 15 15 2020 2525 3535 4545 5050 99 99 10 10

For Equivalent Performance, Using Derate Lowers N1

(RPM) and Achieves More Effective Thrust Reduction

For Equivalent Performance, Using Derate Lowers N1

(RPM) and Achieves More Effective Thrust Reduction

30 30 4040 97 97 95 95

(50)

Other Advantages Of Takeoff Derate

• Permitted on slippery or contaminated runways, where the use of assumed temperature reduced thrust is prohibited

• Permitted with anti-skid system inoperative • May increase maximum takeoff weight when

performance is limited by V_MCG

• May improve aircraft loadability, for some models, by extending aft takeoff CG limit

• Better trimmed for rotation and climbout for most models

• Permitted on slippery or contaminated runways, where the use of assumed temperature reduced thrust is prohibited

• Permitted with anti-skid system inoperative • May increase maximum takeoff weight when

performance is limited by V_MCG

• May improve aircraft loadability, for some models, by extending aft takeoff CG limit

• Better trimmed for rotation and climbout for most models

(51)

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