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Reduced Thrust Takeoff
REDUCED THRUST TAKEOFFREDUCED THRUST TAKEOFFREDUCED THRUST TAKEOFFREDUCED THRUST TAKEOFF
Reduced Thrust Takeoff
Reduced Thrust Takeoff
Objective
Principle
Flexible Takeoff
Derated Takeoff
Flex Temperature Calculation
Reduced Thrust Takeoff
Objective
To explain the two different ways to reduce thrust during takeoff
Flexible takeoffDerated takeoff
To compare the two takeoff techniques
Reduced Thrust Takeoff
Reduced Thrust Takeoff
Objective
Principle
Flexible Takeoff
Derated Takeoff
Flex Temperature Calculation
Reduced Thrust Takeoff
weight
weight
Principle
Reduced Thrust Takeoffweight
weight
You need less Thrust
Principle
Reduced Thrust Takeoff
When your Actual Takeoff Weight is lower than the Maximum takeoff Weight, it is possible to perform a takeoff with less than the maximum takeoff thrust.
This thrust reduction improves engine life andreduces maintenance costs.
Principle
Reduced Thrust Takeoff
engine
aerodynamics
Principle
Which part of the aircraft is concerned ?
Reduced Thrust Takeoff
Benefits of thrust reduction
saves the engine life ( engine stress)
improves engine reliability ( Probability of engine failure)
reduces maintenance costs
Two methods are available:Two methods are available: Flexible TakeoffFlexible Takeoff
Derated TakeoffDerated Takeoff
Principle
Reduced Thrust Takeoff
Principle
Thrust levers : 5 positions on Airbus aircraft
• TOGATOGA : : Takeoff / Go-Around thrustMaximum thrust available. Limited to 5 min with all engines operative. Limited to 10 min with one engine out
• MCTMCT : : Maximum Continuous ThrustNo time limit with one engine outFLX :FLX : Flexible T/O ThrustDRTDRT : Derated T/O thrust
• CLCL : : Max Climb Thrust or Max Cruise Thrust
• IdleIdle
• Max reverseMax reverse
Power
Reduced Thrust Takeoff
Thrust levers : 5 positions on Airbus aircraft
• TOGATOGA : : Takeoff / Go-Around thrustMaximum thrust available. Limited to 5 min with all engines operative. Limited to 10 min with one engine out
• MCTMCT : : Maximum Continuous ThrustNo time limit with one engine outFLX :FLX : Flexible T/O ThrustDRTDRT : Derated T/O thrust
• CLCL : : Max Climb Thrust or Max Cruise Thrust
• IdleIdle
• Max reverseMax reverse
Principle
Power
Reduced Thrust Takeoff
Reminder about engines and thrust
Tref
Thrust
EGT Limit
OAT
Thrust levers TOGA thrust variation with OAT
Reduced Thrust Takeoff
TOGA thrust variation with OAT
Tref
Weight Thrust
EGT Limit
OAT
Reduced Thrust Takeoff
Reduced Thrust Takeoff
Objective
Principle
Flexible Takeoff
Derated Takeoff
Flex Temperature Calculation
Reduced Thrust Takeoff
Principle
Max TOW
Actual TOW
AvailableThrust
NeededThrust
Flat rated Thrust
Tref
Weight Thrust
EGT Limit
OATFlex TempOAT
Flex Take Off :The pilot enters the Flex. Temp. in the MCDU:Setting thrust levers on FLX will provide necessarythrust for takeoff.
Flex temperature
Flex Take Off : what for ?
To enable takeoff without engines at full rate reduces :
the probability of a failure (safety aspect), the engine deterioration rate and associated
maintenance costs (economic aspect).
Reduced Thrust Takeoff
Principle
Max TOW
Actual TOW
AvailableThrust
NeededThrust
Flat rated Thrust
Tref
Weight Thrust
EGT Limit
OATFlex TempOAT
Flex temperature
T Flex max
25 % 25 % reduction maxreduction max
TOGA Thrust (daN)
Thrust reduction mustn't exceed 25 %,to quickly recover full available TOGA thrust if necessary.
Reduced Thrust Takeoff
Max TOW
Actual TOW
AvailableThrust
NeededThrust
Flat rated Thrust
Tref
Weight Thrust
EGT Limit
OATFlex TempOAT
Conditions of application:Flex. take off is to be made only if : 1) TREF < Tflex.
2) OAT < Tflex.
3) Tflex Tflex max
Principle
Flex temperature
T Flex max
Reduced Thrust Takeoff
TOGAThrust
FlexibleThrust
Flat rated Thrust
Tref
Thrust
EGT Limit
OATFlex TempOAT
Flexible Takeoff procedure: at any moment, pilot can recover TOGA
Flexible Takeoff procedure: at any moment, pilot can recover TOGA
Flex Temperature
Reduced Thrust Takeoff
VMCG/VMCA based on maximum TOGA thrustVMCG/VMCA based on maximum TOGA thrust
Tref
Thrust
EGT Limit
OAT
Flex Temperature
Reduced Thrust Takeoff
Conclusion : Which one shall be favored ?Flexible TakeoffFlexible Takeoff
Thrust level is less than TOGA.
Performance for a flex T/O is computed by adjusting the max T/O thrust performance (use of a single T/O chart calculated for TOGA).
Thrust setting parameters for flex T/O are not considered as T/O operating limits.
At any moment it is possible to recover TOGA (same minimum control speeds as TOGA).
Flex T/O is forbidden on contaminated runways.
No performance improvement.
Reduced Thrust Takeoff
Reduced Thrust Takeoff
Objective
Principle
Flexible Takeoff
Derated Takeoff
Flex Temperature Calculation
Reduced Thrust Takeoff
engineengineengine
engineengine
Certified Certified Certified Certified Certified
Each derate level is certified and is associated to a new set of performance data
Derated Takeoff
Reduced Thrust Takeoff
!The TOGA thrust can not beselected any more during T/O.
Derated Takeoff
It consists in decreasing the TOGAthrust by steps of 4%
Max. thrust
available
Weight Thrust
OAT
Reduced Thrust Takeoff
Derated Takeoff
Max. thrust
available
Weight Thrust
OAT
Derated Takeoff benefits :
Reduction of engine stress Reduction of minimum
control speeds (VMCG/VMCA)
Derated Takeoff benefits :
Performance improvement on short runways Allowed on contaminated Runways
Reduced Thrust Takeoff
DeratedThrust
TOGA RatingTOGA Rating
Thrust
OATOAT
Derated Takeoff procedure : pilot cannot recover TOGA.
Derated Takeoff procedure : pilot cannot recover TOGA.
Derated RatingDerated Rating
Derated Takeoff
6 amounts of derate are certified :
4%, 8%, 12%, 16%, 20%, 24%.
6 amounts of derate are certified :
4%, 8%, 12%, 16%, 20%, 24%.
!
Reduced Thrust Takeoff
Min V1 limited by VMCG
V1V1V1V1V1V1V1
On a short or a contaminated runway, the main limitation is most of the time the accelerate-stop distance.
In order to reduce the ASD, V1 is reduced, till reaching VMCG
Derated Takeoff
Reduced Thrust Takeoff
TOGA : VMCG = 111 kts
Derated Takeoff
Reduced Thrust Takeoff
TOGA : VMCG = 111 ktsDERATE (4%) : VMCG = 109 ktsDERATE (8%) : VMCG = 107 kts
Derated Takeoff
Reduced Thrust Takeoff
A319 aircraft // YBHM ATIS : - Takeoff runway 14- Runway condition Water ½”
- CONF 2- Wind 0 kt- Temperature 20°C
- QNH 1,013 hPa- Air conditioning OFF - Total Anti-ice OFF
Which of derate levels gives the best TOW ?Which of derate levels gives the best TOW ?
Reduced Thrust Takeoff
Derated RatingDerated Rating
Derated Takeoff
Tref
Thrust
OAT
VMCG/VMCA based on derated thrust TOGA RatingTOGA Rating
Reduced Thrust Takeoff
Thrust setting parameters are considered as operating limits for T/O.
A new set of performance data is provided in the Flight Manual for each derate level (use of a specific T/O chart for each derate level).
TOGA selection is forbidden.
Thrust level is less than TOGA.
Conclusion : Which one shall be favored ?
Derated T/O is allowed on contaminated runways.
Flexible TakeoffFlexible Takeoff Derated Takeoff Derated Takeoff Thrust level is less than TOGA.
Performance for a flex T/O is computed by adjusting the max T/O thrust performance (use of a single T/O chart calculated for TOGA).
Thrust setting parameters for flex T/O are not considered as T/O operating limits.
At any moment it is possible to recover TOGA (same minimum control speeds as TOGA).
Flex T/O is forbidden on contaminated runways.
No performance improvement. Increase of T/O weight on short and VMCG limited runways.
Reduced Thrust Takeoff
Reduced Thrust Take Off
Objective
Principle
Flexible Takeoff
Derated Takeoff
Flex Temperature Calculation
Reduced Thrust Takeoff
Flex Temperature calculation
YMML ATIS provides the following data :• Takeoff runway 09• Takeoff configuration : CONF 2• Runway condition WET• Wind 0 kt• Temperature 25°C• QNH 1010 hPa
YMML ATIS provides the following data :• Takeoff runway 09• Takeoff configuration : CONF 2• Runway condition WET• Wind 0 kt• Temperature 25°C• QNH 1010 hPa
BLEEDS STATUS :• Air conditioning ON• Total Anti-ice OFF
BLEEDS STATUS :• Air conditioning ON• Total Anti-ice OFF
EXAMPLE EXAMPLE
Determine whether ATOW is lower than MTOW or not (calculate the MTOW with optimized corrections)
If ATOW is lower than MTOW, calculate the flexible temperature (with interpolation) and the take-off speeds
Actual Takeoff Weight :• ATOW = 67 000 Kg
Actual Takeoff Weight :• ATOW = 67 000 Kg
Reduced Thrust Takeoff
YMML ATIS : - Takeoff runway 09 - CONF 2 - Runway condition WET - Wind 0 kt - Temperature 25°C - QNH 1010 hPa- Air Conditioning ON- Total Anti-Ice OFF
MTOW = 75600 Kg
Flex Temperature calculation
Reduced Thrust Takeoff
YMML ATIS : - Takeoff runway 09 - Runway condition WET
- CONF 2- Wind 0 kt- Temperature 25°C
- QNH 1010 hPa- Air conditioning ON - Total Anti-ice OFF
Now, let’s consider optimized corrections !
Flex Temperature calculation
Reduced Thrust Takeoff
- RWY WET- QNH 1010 hPa- Air conditioning ON
Wind = 0 kt
Flex Temperature calculation
Reduced Thrust Takeoff
- RWY WET- QNH 1010 hPa- Air conditioning ON
68°C = Tvmc : OAT above which take-off is limited by minimum control speeds Vmcg and Vmca
If OAT Tvmc, apply correction of the 2 top lines
If OAT > Tvmc, apply correction of the 2 bottom lines
Flex Temperature calculation
Reduced Thrust Takeoff
- RWY WET- QNH 1010 hPa- Air conditioning ON
OAT = 25°C < Tvmc = 68°C
Top lines
Flex Temperature calculation
Wind = 0 kt
Reduced Thrust Takeoff
- RWY WET- QNH 1010 hPa- Air conditioning ON
Wind = 0 kt
Wet correction = - 0.9 t
Flex Temperature calculation
Reduced Thrust Takeoff
- RWY WET- QNH 1010 hPa- Air conditioning ON
1010 - 1013 = - 3 hPa
Wind = 0 kt
Flex Temperature calculation
Reduced Thrust Takeoff
- RWY WET- QNH 1010 hPa- Air conditioning ON
OAT = 25°C < Tvmc = 68°C Top lines
Flex Temperature calculation
Wind = 0 kt
Reduced Thrust Takeoff
- RWY WET- QNH 1010 hPa- Air conditioning ON
1013 - 1010 = 3 hPa
3 hPa x - 0.7t/10hPa = - 0.21 t
Flex Temperature calculation
Wind = 0 kt
Reduced Thrust Takeoff
Wind = +0 kt
- RWY WET- QNH 1010 hPa- Air conditioning ON
Flex Temperature calculation
Reduced Thrust Takeoff
- RWY WET- QNH 1010 hPa- Air conditioning ON
OAT = 25°C < Tvmc = 68°C Top lines
Flex Temperature calculation
Wind = +0 kt
Reduced Thrust Takeoff
- RWY WET- QNH 1010 hPa- Air conditioning ON
AC ON correction = - 1.1 t
Flex Temperature calculation
Wind = +0 kt
Reduced Thrust Takeoff
TOTAL OPTIMIZED CORRECTIONTOTAL OPTIMIZED CORRECTION
QNH Correction = - 210 Kg
Total Correction = - 2 210 Kg MTOW = 75 600 - 2 210 MTOW = 73 390 Kg
AC Correction = - 1 100 Kg
WET Correction = - 900 Kg
MTOW = 73 390 Kg > ATOW = 67 000 Kg OK !
Flex Temperature calculation
Reduced Thrust Takeoff
YMML ATIS : - Takeoff runway 09 - CONF 2 - Runway condition WET
- Temperature 25°C- Wind 0 kt- ATOW= 67 t
- QNH 1010 hPa- Air Conditioning ON- Total Anti-Ice OFF
Conservative method :
Tflex = 59°C
With interpolation :
Tflex = 60°C
Flex Temperature calculation
Reduced Thrust Takeoff
YMML ATIS : - Takeoff runway 09 - CONF 2 - Temperature 25°C- Wind 0 kt- ATOW= 67 t
- Runway condition WET- QNH 1010 hPa- Air Conditioning ON- Total Anti-Ice OFF
Corrections must be applied !
Flex Temperature calculation
Reduced Thrust Takeoff
Tref
Weight Thrust
EGT Limit
OAT
Flat rated Thrust QNH < 1013 hPa or/and Bleeds ON
ATOW
Tflex Tflex
Tflex decreases, hence necessary corrections
Flex Temperature calculation
Reduced Thrust Takeoff
2 types of corrections are possible :
- Conservative corrections (FCOM 2.02.24 P1)
- Optimized corrections (RTOW chart)
Flex Temperature calculation
Reduced Thrust Takeoff
Anti-Icing correction
QNH correction
Air Conditioning Correction Only to be applied A/C OFF to A/C ON
Flex Temperature calculation
Reduced Thrust Takeoff
Flex. take off is to be made only if :
• Tflex > Tref
• Tflex > OAT
• and Tflex Tflex max Tflex max = ISA+55
Flex Temperature calculation
Reduced Thrust Takeoff
Tflex max = ISA+55 Elevation = 395 ft
Tflex max = 14+55=69°C
Tmax = 54°C : take-off is not possible if OAT > 54°C
Flex Temperature calculation
Reduced Thrust Takeoff
YMML ATIS : - Takeoff runway 09 - CONF 2 - Temperature 25°C- Wind 0kt- ATOW= 67 t
- QNH 1010 hPa- Air Conditioning ON- Total Anti-Ice OFF- Runway condition WET
QNH correction :
1013 - 1010 = 3 hPa
3 hPa x -1°C/3hPa = -1°C
QNH correction = -1°C
Flex Temperature calculation
Reduced Thrust Takeoff
YMML ATIS : - Takeoff runway 09 - CONF 2 - Temperature 25°C- Wind 0kt- ATOW= 67 t
- QNH 1010 hPa- Air Conditioning ON- Total Anti-Ice OFF- Runway condition WET
Air Conditioning ON correction :
-3°C
Flex Temperature calculation
Reduced Thrust Takeoff
YMML ATIS : - Takeoff runway 09 - CONF 2 - Temperature 25°C- Wind 0kt- ATOW= 67 t
- QNH 1010 hPa- Air Conditioning ON- Total Anti-Ice OFF- Runway condition WET
With reversers TODA=2436m and TORA=2286m
Wet runway correction :
-8°C
Flex Temperature calculation
Reduced Thrust Takeoff
Summary :
- Chart Tflex = 60°C - Wet correction = - 8°C - QNH correction = -1°C - AC ON correction = -3°C - Corrected T°C = 48°C CT = 48°C > OAT = 25°C
OK!
Flex takeoff is possible and Tflex = 48°C
CT = 48°C ISA+55 CT = 48°C 14+55 = 69°C OK!
CT = 48°C > Tref = 45°C OK !
Flex Temperature calculation
Reduced Thrust Takeoff
2 types of corrections are possible :
- Conservative corrections (FCOM 2.02.24 P1)
- Optimized corrections (RTOW chart)
Flex Temperature calculation
Reduced Thrust Takeoff
- RWY WET- QNH 1010 hPa- Air conditioning ON
Wind = 0 kt
Wet correction for Tflex = - 2 °C
Flex Temperature calculation
For each correction,
compare TFLEX with TVMC
Reduced Thrust Takeoff
- RWY WET- QNH 1010 hPa- Air conditioning ON Wind = 0 kt
QNH correction for Tflex = - 2 °C
Flex Temperature calculation
Reduced Thrust Takeoff
- RWY WET- QNH 1010 hPa- Air conditioning ON
AC ON correction for Tflex = - 3 °C
Flex Temperature calculation
Wind = 0 kt
Reduced Thrust Takeoff
Summary :
- Chart Tflex = 60°C - Wet correction = -2°C - QNH correction = -2°C - AC ON correction = -3°C - Corrected T°C = 53°C CT = 53°C > OAT = 25°C
OK!
Flex takeoff is possible and Tflex = 53°C
CT = 53°C ISA+55 CT = 53°C 14+55 = 69°C OK!
CT = 53°C > Tref = 45°C OK!
Flex Temperature calculation
Reduced Thrust Takeoff
YMML ATIS : - Takeoff runway 09 - CONF 2 - Temperature 25°C- Wind 0 kt- ATOW= 67 t
- QNH 1010 hPa- Air Conditioning ON- Total Anti-Ice OFF- Runway condition WET
Speeds :
V1 = 136 kt Vr = 137 kt V2 = 140 kt
Flex Temperature calculation
Reduced Thrust Takeoff
YMML ATIS : - Takeoff runway 09 - CONF 2 - Temperature 25°C- Wind 0 kt- ATOW= 67 t
- QNH 1010 hPa- Air Conditioning ON- Total Anti-Ice OFF- Runway condition WET
Only wet corrections for speeds !
Flex Temperature calculation
Reduced Thrust Takeoff
- RWY WET- QNH 1010 hPa- Air conditioning ON
V1 =136 - 8 = 128 kt Vr = 137 - 1 = 136 kt V2 = 140 - 1 = 139 kt
Flex Temperature calculation
V1/ VR/ V2 = - 8 / - 1 / - 1 Wet correction:
Wind = 0 kt
Reduced Thrust Takeoff
YMML ATIS provides the following data :• Takeoff runway 09• Takeoff configuration : 2 • Runway condition DRY• Wind 20 kt• Temperature -5°C• QNH 1003 hPa
YMML ATIS provides the following data :• Takeoff runway 09• Takeoff configuration : 2 • Runway condition DRY• Wind 20 kt• Temperature -5°C• QNH 1003 hPa
BLEEDS STATUS :• Air conditioning ON• Total Anti-ice OFF
BLEEDS STATUS :• Air conditioning ON• Total Anti-ice OFF
EXERCISEEXERCISE
Actual Takeoff Weight :• ATOW = 69 000 Kg
Actual Takeoff Weight :• ATOW = 69 000 Kg
Determine whether ATOW is lower than MTOW or not (use optimized corrections)
If ATOW is lower than MTOW, calculate the flexible temperature and the takeoff speeds
Flex Temperature calculation
Reduced Thrust Takeoff
EXERCISE : ANSWEREXERCISE : ANSWER
MTOW = 78 200 Kg > ATOW = 69 000 Kg
Flex Temperature = 55°C > TREF (45°C)
Flexible takeoff is possible
V1 = 141 kt, VR = 142 kt, V2 = 145 kt
MTOW = 78 200 Kg > ATOW = 69 000 Kg
Flex Temperature = 55°C > TREF (45°C)
Flexible takeoff is possible
V1 = 141 kt, VR = 142 kt, V2 = 145 kt
Flex Temperature calculation
Reduced Thrust Takeoff
MTOW = 79 900 Kg
Flex Temperature calculation
YMML ATIS : - Takeoff runway 09 - CONF 2 - Temperature -5°C- Wind 20 kt- ATOW= 69 t
- QNH 1003 hPa- Air Conditioning ON- Total Anti-Ice OFF- Runway condition DRY
Reduced Thrust Takeoff
Correction : = - 600 - 1100 = 1700 kg
Flex Temperature calculation - RWY DRY- QNH 1003 hPa- Air conditioning ON
Reduced Thrust Takeoff
YMML ATIS : - Takeoff runway 09 - CONF 2 - Temperature -5°C- Wind 20 kt- ATOW= 69 t
- QNH 1003 hPa- Air Conditioning ON- Total Anti-Ice OFF- Runway condition DRY
Conservative result : Chart Temp = 59
°C
With interpolation : Chart Temp =
60 °C
Flex Temperature calculation
Reduced Thrust Takeoff
Correction : = - 2 - 3 = - 5oC
Conservative result : Corr. Temp = 59 - 5 = 54°C
With interpolation : Corr. Temp = 60 - 5 = 55°C
Flex Temperature calculation - RWY DRY- QNH 1003 hPa- Air conditioning ON
Reduced Thrust Takeoff
CT > OAT = - 5ºCCT > TREF = 45ºC CT T FLEX MAX = 69ºC
Conservative result : Corr. Temp = 54°C
With interpolation : Corr. Temp = 55°C
Flex Temperature calculation
Flexible takeoff is possible and Tflex = 55°C
Reduced Thrust Takeoff