Reduced Thrust Take-Off
Eng. Bruno Moreira
Engine Performance
Principle
Flexible take off
Derated take off
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weight
Principle
weight
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weight
Principle
weight
You need less Thrust
Eng. Bruno Moreira
Principle
When your Actual Take-off Weight is lower than the
Maximum take-off Weight, you can perform a take off with
less than the max take-off thrust.
This thrust reduction improves engine life and
reduces maintenance costs.
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Which part of the aircraft is concerned ?
engine
aerodynamics
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Reminder about engines and thrust
Trust levers
Thrust
Thrust variation with OAT
EGT Limit
Tref
OAT
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Thrust levers
5 positions on Airbus aircraft :
TOGA : Take Off - Go Around
Maximum thrust available.
Its use cant exceed 10 min.
MCT : Maximum Continuous Thrust
FLX : Flex T/O Thrust ...
Maximum thrust for long use.
CL : Climb Thrust.
Idle : No power.
Max reverse.
Power
Eng. Bruno Moreira
Thrust levers
5 positions on Airbus aircraft :
TOGA : Take Off - Go Around
Maximum thrust available.
Its use cant exceed 10 min.
MCT : Maximum Continuous Thrust
FLX : Flex T/O Thrust ...
Maximum thrust for long use.
CL : Climb Thrust.
Idle : No power.
Max reverse.
Power
Eng. Bruno Moreira
Thrust variation with OAT
Weight
Thrust
N1
EGT Limit
Tref
10
OAT
Eng. Bruno Moreira
Engine Performance
Principle
Flexible take off
Derated take off
11
Eng. Bruno Moreira
Flex Temperature
Flex Take Off : what for ?
Weight
Max TOW
To enable take off without engines at full rate reduces :
Flex Take Off :
Thrust
The
thepilot
probability
a failure
(safety
type theofFlex.
Temp.
in theaspect),
MCDU :
Setting
the engine
ratewill
andprovide
associated
thrustdeterioration
levers on FLX
necessary
maintenance
costs (economic aspect).
thrust
take
off.
Flatfor
rated
Thrust
Available
Thrust
EGT Limit
Actual TOW
Needed
Thrust
OAT
12
Tref
Flex Temp
OAT
Eng. Bruno Moreira
Flex Temperature
Weight
Max TOW
Thrust
Available
Thrust
Flat rated Thrust
EGT Limit
Actual TOW
Needed
Thrust
25 %
reduction max
Thrust reduction mustn't exceed 25 %,
to
quickly
recover
TOGA
Thrust
(daN) full available TOGA thrust if necessary.
OAT
13
Tref
Flex Temp
T Flex max
OAT
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Flex Temperature
Conditions of application:
Weight
Max TOW
Flex. take off is to be made only if
TREF < Tflex.
if daily OAT < Tflex.
and Tflex < Tflex max
Thrust
Available
Thrust
Flat rated Thrust
EGT Limit
Actual TOW
Needed
Thrust
T Flex max
OAT
14
Tref
Flex Temp
OAT
Eng. Bruno Moreira
Engine Performance
Principle
Flexible take off
Derated take off
15
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Certified
Certified
Certified
Certified
Certified
engine
engine
engine
engine
engine
16
Eng. Bruno Moreira
Derated take off
It consists
decreasing
the TOGA
Advantages of Derated
Takein
Off
::
maximum thrust by 4% increments.
Significant reduction of engine stress (like Flex T/O)
Decreasing TOGA will The
also original
decreaseTOGA
VMCG, will
and
TOGA Thrust (daN)
be available during T/O.
the available value of Vnever
1, which enables short T/O.
Not forbidden on contaminated Runways
Principle :
MTOW (t)
285
280
25
23
275
270
265
260
21
Max. thrust
available
19
17
OAT (C)
255
CF6-50A
15
-10
17
-5
10
15
20
25
30
35
40
Eng. Bruno Moreira
Engine Performance
Thrust levers
Flexible take off
Derated take off
18
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Comparison of the two methods
Flex (Reduced)
19
Derated
At any moment, it is
possible to recover TOGA
TOGA selection is not
allowed
VMCA and VMCG are
always the same
VMCA and VMCG change
with Derated thrust.
Not allowed on
contaminated Runways.
Not forbidden on Wet and
contaminated Runways
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TAP RTOW
FOR GIVEN W/C, ATOW
AND CONFIGURATION
Corrections on temperature
if flexible takeoff performed
READ TFLEX, V1/VR/V2
FROM RTOW CHART
AIR COND.
OR ANTI-ICE
CORRECTIONS OR
QNH > 1013.2 HPA
NO
YES
NO
INTER / EXTRAPOLATE TEMPERATURE
CORRECTION FROM LINE 3
NO SPEED CORRECTION
CG
MORE FORWARD THAN
25%
QNH below 1013 hPa
Subtract 1C/2 hPa
Engine A/Ice ON*
Subtract 1C
Total A/Ice ON*
Subtract 2C
Air conditioning ON
Subtract 7C
YES
DECREASE TFLEX BY 2C
INCREASE V1, VR AND V2 BY 1 KT
NO
TFLEX > TREF
AND
TFLEX > OAT
NO
FLEXIBLE TAKEOFF NOT POSSIBLE.
USE TOGA THRUST AND SPEEDS DETERMINED
FOR MTOW, OR THE SPEEDS FOR THE ACTUAL
WEIGHT IF THEY ARE ALL LOWER
YES
TOGA MANDATORY?
YES
NO
MAXIMUM FLEXIBLE TEMPERATURE = FINAL
TEMPERATURE LIMITED TO TMAXFLEX ON THE
LAST ROW OF THE TAKEOFF CHART
V1/VR/V2 AS CALCULATED
20
No correction except if
actual pressure altitude is
between 2000ft and 4000ft:
subtract 1C/3hPa
YES
APPLY TEMPERATURE CORRECTIONS
FROM SECTION 2.8.
NO SPEED CORRECTION
QNH < 1013.2 HPA
QNH above 1013 hPa
FLEXIBLE TAKEOFF NOT POSSIBLE
USE TOGA THRUST AND
V1/VR/V2 AS CALCULATED
A320-211/214
TFLEX
Eng. Bruno Moreira
