B737-Reduced_Thrust_Considerations

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B737-Reduced_Thrust_Considerations

 

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737.1
Reduced Thrust Considerations
Taakkeeooffff Peerrffoorrmaanccee Maarrggiinss
Dick Mayward
Flight Operations Engineering
Boeing Commercial Airplanes
May 2004
The Boeing Company 737.2
Common Misconceptions
• “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
used, then there will be no stopping margin left if the
takeoff is aborted.”
The Boeing Company 737.3
Regulatory Compliance
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//AMJJ 2255--1133
The Boeing Company 737.4
Regulatory Performance Requirements
• Have sufficient runway length for:
– 115% of all-engine takeoff distance
– One engine inoperative takeoff distance
– Accelerate-stop distance
• Achieve the one engine inoperative minimum climb gradient
for:
– First segment
– Second segment
– Final segment
• Clear all obstacles in the intended takeoff flight path
The Boeing Company 737.5
Effect of Temperature on True
Airspeed and Thrust
• Air density is lower at higher outside air
temperature (OAT)
• For a given indicated airspeed (IAS), true
airspeed (TAS) is higher at higher OAT
• For a given reduced engine power setting (N1
or EPR), lower air density (higher OAT) results
in lower thrust
The Boeing Company 737.6
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
The Boeing Company 737.7
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 Boeing Company 737.8
The True Airspeed Effect
148
146
144
142
140
True
airspeed,
kt
Assumed ttemperratturre,, °C
OAT – assumed temperature difference
Assumed true airspeed
Actual true airspeed at OAT, 15°C
30 32 34 36 38 40
The Boeing Company 737.9
737-800W WITH CFM56-7B27 ENGINES
PRESSURE ALTITUDE 0 FT
RUNWAY LENGTH 7000 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 V R V2
(KT)
MTOW
(KG)
PERF
LIM
V1 V R V2
(KT)
60 60400 FLD 134 135 140 55900 FLD 131 131 134
55 62200 FLD 136 137 142 57700 FLD 133 133 137
50 65000 FLD 138 139 146 59700 FLD 134 135 139
45 67200 FLD 140 141 148 61900 FLD 136 137 142
40 69300 FLD 141 143 150 64100 FLD 138 139 144
38 70300 FLD 142 144 151 65000 FLD 139 140 145
36 71100 FLD 142 145 152 65800 FLD 139 141 146
34 72000 FLD 143 145 153 66700 FLD 140 141 147
32 72900 FLD 143 146 154 67700 FLD 141 142 148
30 73700 FLD 144 147 155 68600 FLD 141 143 149
25 74300 FLD 144 147 156 69200 FLD 142 144 150
20 75000 FLD 145 148 156 69800 FLD 143 144 151
15 75600 FLD 146 149 157 70300 FLD 144 145 151
10 76200 FLD 146 149 157 71000 FLD 144 146 152
Maximum Allowable
Assumed Temperature 38°C
27K, OAT 15°C
Takeoff Weight 70300 KG
The Assumed Temperature Method
The Boeing Company 737.10
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
The Boeing Company 737.11
6800
6600
6400
6200
6000
Field
length, ft
Assumed ttemperratturre,, °C
Runway length
Actual balanced field length
30 32 34 36 38 40
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
7000
28
Fiieelldd Leennggtthh Maarrggiinn
875 ft
493 ft
The Boeing Company 737.12
25500
25000
24500
24000
23500
Net thrust/
engine at
V1, lb
Assumed ttemperratturre,, °C
Rated thrust
Actual thrust
30 32 34 36 38 40
Thrust Margin Decreases
With Lower Assumed Temperature
26000
28
Raatteedd Thhrruusstt Veerrssuuss Accttuuaall Thhrruusstt • 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
206 llb
139 llb
The Boeing Company 737.13
737-800W W ITH CFM56-7B27 ENGINES
PRESSURE ALTITUDE 0 FT
RUNWAY LENGTH 7000 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 60400 FLD 134 135 140 55900 FLD 131 131 134
55 62200 FLD 136 137 142 57700 FLD 133 133 137
50 65000 FLD 138 139 146 59700 FLD 134 135 139
45 67200 FLD 140 141 148 61900 FLD 136 137 142
40 69300 FLD 141 143 150 64100 FLD 138 139 144
38 70300 FLD 142 144 151 65000 FLD 139 140 145
36 71100 FLD 142 145 152 65800 FLD 139 141 146
34 72000 FLD 143 145 153 66700 FLD 140 141 147
32 72900 FLD 143 146 154 67700 FLD 141 142 148
30 73700 FLD 144 147 155 68600 FLD 141 143 149
25 74300 FLD 144 147 156 69200 FLD 142 144 150
20 75000 FLD 145 148 156 69800 FLD 143 144 151
15 75600 FLD 146 149 157 70300 FLD 144 145 151
10 76200 FLD 146 149 157 71000 FLD 144 146 152
Lower Takeoff Weight May Permit Higher
Maximum Allowable Assumed Temperature
The Boeing Company 737.14
145
140
135
130
True
airspeed,
kt
Assumed ttemperratturre,, °C
Assumed true airspeed
Actual true airspeed at OAT
40 45 50 55 60 65
True Airspeed Effect Increases
With Higher Assumed Temperature
150
35
6 kt
10 kt
Trruuee Aiirrssppeeeedd Effffeecctt
The Boeing Company 737.15
22000
21000
20000
19000
18000
Net thrust/
engine at
V1, lb
Assumed ttemperratturre,, °C
Rated thrust
Actual thrust
40 45 50 55 60 65
Thrust Margin Increases
With Higher Assumed Temperature
23000
35
650 llb
• 737-800W / CFM56-7B27
• Pressure Altitude 0 ft, OAT 15°C
• Runway Length 7000 ft, Dry
• Flaps 5, Standard Takeoff
Speeds
24000 206 llb
25000
Raatteedd Thhrruusstt Veerrssuuss Accttuuaall Thhrruusstt
The Boeing Company 737.16
• 737-800W / CFM56-7B27
• Pressure Altitude 0 ft, OAT 15°C
• Runway Length 7000 ft, Dry
• Flaps 5, Standard Takeoff
Speeds
6600
6400
6200
6000
5800
Field
length, ft
Assumed ttemperratturre,, °C
Runway length
Actual balanced field length
40 45 50 55 60 65
Field Length Margin Due to the True Airspeed Effect
Increases With Higher Assumed Temperature
6800
35
493 ft
1035 ft
7200
7000
Fiieelldd Leennggtthh Maarrggiinn
The Boeing Company 737.17
• 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
Actual thrust and climb gradient
Rated thrust at the assumed temp
The Boeing Company 737.18
737-800W W ITH 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 141 141 145 56200 CLB 132 132 134
40 68100 CLB 143 144 148 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
27K, OAT 10°C
Takeoff Weight 71000 KG
Maximum Allowable
Assumed Temperature 35°C
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
The Boeing Company 737.19
• 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..6
2..4
2..2
Climb
gradient
, %
Assumed ttemperratturre,, °C
Regulatory minimum
Actual gradient
20 25 30 35 40
3..0
15
3..4
3..2
Climb Gradient Increases With Lower
Assumed Temperature Due to Higher Thrust
0.9 %
Clliimbb Grraaddiieenntt Maarrggiinn
0.14 %
The Boeing Company 737.20
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 141 141 145 56200 CLB 132 132 134
40 68100 CLB 143 144 148 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
Lower Takeoff Weight May Permit A Higher
Maximum Allowable Assumed Temperature
The Boeing Company 737.21
• 737-800W / CFM56-7B27
• Pressure Altitude 5000 ft, OAT 10°C
• Runway Length 12000 ft, Dry
• Flaps 5, Standard Takeoff Speeds
Climb
gradient
, %
Assumed ttemperratturre,, °C
30 35 40 45 50 55
Climb Gradient Margin Due to the True Airspeed
Effect Increases With Higher Assumed Temperature
60 65
2..6
2..4
Regulatory minimum
Actual gradient
0.25 %
0.14 %
2..3
2..5
2..7
Clliimbb Grraaddiieenntt Maarrggiinn
The Boeing Company 737.22
737-800W WITH CFM56-7B27 ENGINES
PRESSURE ALTITUDE 0 FT
RUNWAY 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
Maximum Allowable
Assumed Temperature 41°C
27K, OAT 15°C
Takeoff Weight 73500 KG
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
The Boeing Company 737.23
• 737-800W / CFM56-7B27
• Pressure Altitude 0 ft
• 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
60
40
20
Net
clearance,
ft
Assumed ttemperratturre,, °C
Regulatory minimum
Actual net clearance
30 32 34 36 38
100
28
120
Obbssttaaccllee Clleeaarraannccee Maarrggiinn
Net Clearance Margin Increases With Lower
Assumed Temperature Due to Higher Thrust
26 ft
81 ft
40 42
The Boeing Company 737.24
737-800W WITH CFM56-7B27 ENGINES
PRESSURE ALTITUDE 0 FT
RUNWAY 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
Lower Takeoff Weight May Permit Higher
Maximum Allowable Assumed Temperature
The Boeing Company 737.25
• 737-800W / CFM56-7B27
• Pressure Altitude 0 ft, OAT 15°C
• Runway Length 9000 ft, Dry
• Obstacle: 50 ft Ht at 1000 ft Dist from liftoff
end
• Flaps 5, Standard Takeoff Speeds
60
40
20
Net
clearance,
ft
Assumed ttemperratturre,, °C
Regulatory minimum
Actual net clearance
40 45 50 55 60
80
Obbssttaaccllee Clleeaarraannccee Maarrggiinn
65
Net Clearance Margin Due to True Airspeed Effect
Increases With Higher Assumed Temperature
58 ft
69 ft
The Boeing Company 737.26
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
The Boeing Company 737.27
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)
The Boeing Company 737.28
• 737-800W / CFM56-7B27
• Pressure Altitude 0 ft
• Flaps 5, Dry Runway, Standard
Speeds
• OAT 15°C, Takeoff Weight 60400 kg
140
135
130
125
Takeoff
speeds,
KIAS
Assumed ttemperratturre,, °C
V1
VR
25 30 35 40 45 50
145
Thhrruusstt Effffeecctt oonn Taakkeeooffff SSppeeeeddss
55 60
Takeoff Speeds (IAS) Vary
With Assumed Temperature
V2
65
The Boeing Company 737.29
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
98. 8 / 98.8%
C G TRIM
22.5% 5 . 2 5
RUNW A Y
< P ERF 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.
Quick
Reference
Handbook
The Boeing Company 737.30
737-800W WITH CFM56-7B27 ENGINES
PRESSURE ALTITUDE 0 FT
RUNWAY LENGTH 7000 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 60400 FLD 134 135 140 55900 FLD 131 131 134
55 62200 FLD 136 137 142 57700 FLD 133 133 137
50 65000 FLD 138 139 146 59700 FLD 134 135 139
45 67200 FLD 140 141 148 61900 FLD 136 137 142
40 69300 FLD 141 143 150 64100 FLD 138 139 144
38 70300 FLD 142 144 151 65000 FLD 139 140 145
36 71100 FLD 142 145 152 65800 FLD 139 141 146
34 72000 FLD 143 145 153 66700 FLD 140 141 147
32 72900 FLD 143 146 154 67700 FLD 141 142 148
30 73700 FLD 144 147 155 68600 FLD 141 143 149
25 74300 FLD 144 147 156 69200 FLD 142 144 150
20 75000 FLD 145 148 156 69800 FLD 143 144 151
15 75600 FLD 146 149 157 70300 FLD 144 145 151
10 76200 FLD 146 149 157 71000 FLD 144 146 152
27K, OAT 15°C
Takeoff Weight 60400 KG
Maximum Allowable
Assumed Temperature 60°C
Overspeed
Use Speeds for the Maximum Allowable Assumed
Temperature, Ignoring Thrust Effect on Speeds
The Boeing Company 737.31
737-800W / CFM56-7B27
Pressure Altitude 0 ft, OAT 15°C
Dry Runway, Standard Speeds
Flaps 5, Takeoff Weight 60400 kg
15°C 128 / 131 / 143
45°C 131 / 133 / 142
60°C 134 / 135 / 140
V1 / VR / V2
(kt)
Assumed
temperature
Proper Takeoff Speeds From QRH
The Boeing Company 737.32
737-800W WITH CFM56-7B27 ENGINES
PRESSURE ALTITUDE 0 FT
RUNWAY LENGTH 7000 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 60400 FLD 134 135 140 55900 FLD 131 131 134
55 62200 FLD 136 137 142 57700 FLD 133 133 137
50 65000 FLD 138 139 146 59700 FLD 134 135 139
45 67200 FLD 140 141 148 61900 FLD 136 137 142
40 69300 FLD 141 143 150 64100 FLD 138 139 144
38 70300 FLD 142 144 151 65000 FLD 139 140 145
36 71100 FLD 142 145 152 65800 FLD 139 141 146
34 72000 FLD 143 145 153 66700 FLD 140 141 147
32 72900 FLD 143 146 154 67700 FLD 141 142 148
30 73700 FLD 144 147 155 68600 FLD 141 143 149
25 74300 FLD 144 147 156 69200 FLD 142 144 150
20 75000 FLD 145 148 156 69800 FLD 143 144 151
15 75600 FLD 146 149 157 70300 FLD 144 145 151
10 76200 FLD 146 149 157 71000 FLD 144 146 152
27K, OAT 15°C
Takeoff Weight 60400 KG
Maximum Allowable
Assumed Temperature 60°C
Overspeed
Use Speeds for the Lower Assumed Temperature,
Ignoring Weight Effect on Speeds
The Boeing Company 737.33
6000
6200
6400
6600
6800
7000
7200
28 30 32 34 36 38 40
• 737-800W / CFM56-7B27
• Pressure Altitude 0 ft, OAT 15°C
• Runway Length 7000 ft, Dry
• Flaps 5, Takeoff Weight 70300 kg
• Max Allowable Assumed Temp
38°C
Field
length,
ft
Fiieelldd Leennggtthh Maarrggiinn Wiitthh Ovveerrssppeeeedd
Overspeed Reduces Field Length Margin
Proper
speeds
Runway length available
Overspeed
– Max assumed
temp Overspeed
– Lower assumed
temp
Assumed ttemperratturre,, °°C
The Boeing Company 737.34
• 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,
%
Clliimbb Grraaddiieenntt Maarrggiinn Wiitthh Ovveerrssppeeeedd
Proper
speeds
Regulatory minimum
Effect of Overspeed on Climb Gradient
2..2
2..4
2..6
2..8
3..0
3..2
3..4
3..6
15 20 25 30 35 40
Assumed ttemperratturre,, °°C
Overspeed
– Lower assumed temp
Overspeed
– Max assumed temp
The Boeing Company 737.35
• 737-800W / CFM56-7B27
• Pressure Altitude 0 ft, OAT 15°C
• Runway Length 9000 ft, Dry
• 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
Assumed ttemperratturre,, °°C
Obbssttaaccllee Clleeaarraannccee Wiitthh Ovveerrssppeeeedd
Overspeed Reduces
Obstacle Clearance Margin
20
40
60
80
100
120
28 30 32 34 36 38 40 42
Proper speeds
Regulatory minimum
Overspeed
– Max assumed
temp
Overspeed
– Lower assumed
temp
The Boeing Company 737.36
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.
The Boeing Company 737.37
7 3 7 -80 0W W ITH C FM 56 -7B 2 7 ENG IN E S
PR ESSURE A LT ITUDE 0 FT
R U NW A Y LE N G T H 7 0 0 0 F T , D R Y
NO O BSTACLES
27K , STANDARD TAKEO FF S P EED S
O AT
(C )
FLA P S 5
A /C A U TO
FLA P S 15
A /C A U TO
FLA P S 5
A /C O FF
60 60400 6 0 800 6 1 300
55 62200 6 3 400 6 3 200
50 65000 6 6 100 6 6 000
45 67200 6 8 200 6 8 100
40 69300 7 0 500 7 0 300
38 70300 7 1 400 7 1 100
36 71100 7 2 300 7 2 000
34 72000 7 3 200 7 2 800
32 72900 7 4 100 7 3 600
30 73700 7 5 000 7 4 400
25 74300 7 5 700 7 5 000
20 75000 7 6 300 7 5 600
15 75600 7 6 900 7 6 200
10 76200 7 7 600 7 6 900
Means to Maximize Thrust
Reduction and Margin
OAT 15°C
Takeoff Weight 70300 KG
Peerrffoorrmaannccee Liimiitteedd bbyy Fiieelldd Leennggtthh
The Boeing Company 737.38
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
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
The Boeing Company 737.39
7 3 7 -800W W ITH CFM5 6 -7B2 7 ENGINES
PRESSUR E ALTITUDE 5000 FT
RUNW AY L ENGTH 12000 FT , DRY
NO O BSTACLES
27K, A /C AUTO
OAT
(C )
FLA P S 5
NO IMP C LB
FLA P S 1
NO IMP C LB
FLA P S 5
W ITH IMP CLB
60 57300 59300 60600
55 59900 62000 63200
50 62500 64700 65700
45 65100 67400 68300
40 68100 70500 71100
39 68700 71100 71600
37 69900 72400 72500
35 71000 73100 73400
30 73900 74000 75300
25 75400 74800 76500
20 76400 75500 77300
15 76400 76100 77700
10 76500 76800 78100
Means to Maximize
Thrust Reduction and Margin
OAT 10°C
Takeoff Weight 71000 KG
Peerrffoorrmaannccee Liimiitteedd bbyy Clliimbb oorr Obbssttaaccllee Clleeaarraannccee
The Boeing Company 737.40
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
The Boeing Company 737.41
The Takeoff Derate Method
• Available for use on slippery or contaminated runways
and with inoperative antiskid
• Can be combined with use of assumed temperature
The Boeing Company 737.42
737-800W WITH CFM56-7B27 ENGINES
PRESSURE ALTITUDE 0 FT
RUNWAY LENGTH 7000 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 60400 FLD 134 135 140 55900 FLD 131 131 134
55 62200 FLD 136 137 142 57700 FLD 133 133 137
50 65000 FLD 138 139 146 59700 FLD 134 135 139
45 67200 FLD 140 141 148 61900 FLD 136 137 142
40 69300 FLD 141 143 150 64100 FLD 138 139 144
38 70300 FLD 142 144 151 65000 FLD 139 140 145
36 71100 FLD 142 145 152 65800 FLD 139 141 146
34 72000 FLD 143 145 153 66700 FLD 140 141 147
32 72900 FLD 143 146 154 67700 FLD 141 142 148
30 73700 FLD 144 147 155 68600 FLD 141 143 149
25 74300 FLD 144 147 156 69200 FLD 142 144 150
20 75000 FLD 145 148 156 69800 FLD 143 144 151
15 75600 FLD 146 149 157 70300 FLD 144 145 151
10 76200 FLD 146 149 157 71000 FLD 144 146 152
Runway Length Consideration
OAT 15°C
Takeoff Weight 70300 KG
The Boeing Company 737.43
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
The Boeing Company 737.44
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
OAT 10°C
Takeoff Weight 71000 KG
The Boeing Company 737.45
24K Derate
OAT 10°C
27K
assume 35°C
2.4 2.54
Parameter
One Engine Inoperative
Climb Gradient (%)
Using Derate
Reduces Performance Margins
The Boeing Company 737.46
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
OAT 15°C
Takeoff Weight 73500 KG
The Boeing Company 737.47
Using Derate Reduces
Performance Margins
24K Derate
OAT 15°C
27K
assume 41°C
35 61
Parameter
Net Clearance (ft)
The Boeing Company 737.48
98
96
94
93
N1
OAT,, °C
27K and max allowable assumed temp
24K Derate at OAT
15 20 25 35 45 50
99
10
For Equivalent Performance, Using Derate Lowers N1
(RPM) and Achieves More Effective Thrust Reduction
30 40
97
95
The Boeing Company 737.49
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 VMCG
• May improve aircraft loadability, for some models,
by extending aft takeoff CG limit
• Better trimmed for rotation and climbout
for most models
The Boeing Company 737.50
Summary On Performance Margins
• Extra performance margins are inherent in the
Assumed Temperature method of reduced thrust,
including at the maximum allowable assumed
temperature
• Using those inherent margins for takeoff weight
planning is prohibited!
The Boeing Company 737.51

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