EDE Reduced Thrust TOFF

Reduced Thrust Takeoff

REDUCED THRUST TAKEOFFREDUCED THRUST TAKEOFFREDUCED THRUST TAKEOFFREDUCED THRUST TAKEOFF



Objective

Principle

Flexible Takeoff

Derated Takeoff

Flex Temperature Calculation


Objective

To explain the two different ways to reduce thrust during takeoff

Flexible takeoffDerated takeoff

To compare the two takeoff techniques



Objective

Principle

Flexible Takeoff

Derated Takeoff



weight

weight

Principle

Reduced Thrust Takeoffweight

weight

You need less Thrust

Principle


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


engine

aerodynamics

Principle

Which part of the aircraft is concerned ?


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


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


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


Reminder about engines and thrust

Tref

Thrust

EGT Limit

OAT

Thrust levers TOGA thrust variation with OAT


TOGA thrust variation with OAT

Tref

Weight Thrust

EGT Limit

OAT



Objective

Principle

Flexible Takeoff

Derated 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).


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.


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


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


VMCG/VMCA based on maximum TOGA thrustVMCG/VMCA based on maximum TOGA thrust

Tref

Thrust

EGT Limit

OAT

Flex Temperature


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.



Objective

Principle

Flexible Takeoff

Derated 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


!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


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


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%.

!


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


TOGA : VMCG = 111 kts

Derated Takeoff


TOGA : VMCG = 111 ktsDERATE (4%) : VMCG = 109 ktsDERATE (8%) : VMCG = 107 kts

Derated 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 ?


Derated RatingDerated Rating

Derated Takeoff

Tref

Thrust

OAT

VMCG/VMCA based on derated thrust TOGA RatingTOGA Rating


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 Take Off

Objective

Principle

Flexible Takeoff

Derated 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


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



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



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 !



- RWY WET- QNH 1010 hPa- Air conditioning ON

Wind = 0 kt




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




OAT = 25°C < Tvmc = 68°C

Top lines


Wind = 0 kt



Wind = 0 kt

Wet correction = - 0.9 t




1010 - 1013 = - 3 hPa

Wind = 0 kt




OAT = 25°C < Tvmc = 68°C Top lines


Wind = 0 kt



1013 - 1010 = 3 hPa

3 hPa x - 0.7t/10hPa = - 0.21 t


Wind = 0 kt


Wind = +0 kt





OAT = 25°C < Tvmc = 68°C Top lines


Wind = +0 kt



AC ON correction = - 1.1 t


Wind = +0 kt


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 !



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



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 !



Tref

Weight Thrust

EGT Limit

OAT

Flat rated Thrust QNH < 1013 hPa or/and Bleeds ON

ATOW

Tflex Tflex

Tflex decreases, hence necessary corrections



2 types of corrections are possible :

- Conservative corrections (FCOM 2.02.24 P1)

- Optimized corrections (RTOW chart)



Anti-Icing correction

QNH correction

Air Conditioning Correction Only to be applied A/C OFF to A/C ON



Flex. take off is to be made only if :

• Tflex > Tref

• Tflex > OAT

• and Tflex Tflex max Tflex max = ISA+55



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



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





Air Conditioning ON correction :

-3°C





With reversers TODA=2436m and TORA=2286m

Wet runway correction :

-8°C



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 !



2 types of corrections are possible :

- Conservative corrections (FCOM 2.02.24 P1)

- Optimized corrections (RTOW chart)




Wind = 0 kt

Wet correction for Tflex = - 2 °C


For each correction,

compare TFLEX with TVMC


- RWY WET- QNH 1010 hPa- Air conditioning ON Wind = 0 kt

QNH correction for Tflex = - 2 °C




AC ON correction for Tflex = - 3 °C


Wind = 0 kt


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!





Speeds :

V1 = 136 kt Vr = 137 kt V2 = 140 kt





Only wet corrections for speeds !




V1 =136 - 8 = 128 kt Vr = 137 - 1 = 136 kt V2 = 140 - 1 = 139 kt


V1/ VR/ V2 = - 8 / - 1 / - 1 Wet correction:

Wind = 0 kt


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



EXERCISEEXERCISE



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



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



MTOW = 79 900 Kg


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


Correction : = - 600 - 1100 = 1700 kg

Flex Temperature calculation - RWY DRY- QNH 1003 hPa- Air conditioning ON


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



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


CT > OAT = - 5ºCCT > TREF = 45ºC CT T FLEX MAX = 69ºC

Conservative result : Corr. Temp = 54°C

With interpolation : Corr. Temp = 55°C


Flexible takeoff is possible and Tflex = 55°C

EDE Reduced Thrust TOFF

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