AIRBUS THRUST REDUCTION & ACCELERATION ALTITUDE

Regulations perspective :

EASA ( European union aviation safety agency ) and FAA ( Federal aviation administration ) regulate and govern the setting of thrust reduction and acceleration altitude,both allow for operator specific procedures within certain safety parameters .

EASA Guidline :

EASA OPS (CAT.POL.A200 and AMC /GM to part -cat ) key point :

Thrust reduction Altitude :

1-It must comply with noise abatement procedures if required ( NADAP 1 OR NADAP 2 ).

2-Set at or above 400 feet AGL unless otherwise specified by aircraft manufacturer guidelines or specific obstacle clearance requirements.

Acceleration Altitude :

1-For airport’s with a specific noise abatement procedures, operators often adjust the acceleration altitude ( NADAP1 OR NADAP 2 ).

2-Commonly set at 1000 feet AGL as standard , but it can vary depending on obstacle clearance,terrain and airport-specific procedures.

FAA Guidelines :

As under 14 CFR part 91,121 and 135 the FAA does not explicitly define a regulatory thrust reduction or acceleration altitude but instead relies on manufacturer recommendations ,obstacle clearance requirements and operators SOPs.

Thrust reduction altitude:

1-follows manufacturer guidelines to be 400 feet or higher to ensure compliance with performance requirements.

Acceleration altitude :

Often set at 1000 feet AGL as default , it may be adjusted based on :

1- Noise abasement procedures .

2- Obstacle clearance altitude .

Is it correct to set the acceleration altitude lower than the thrust reduction altitude?

Answer is NO , this is based on both a manufacturer recommendations and standard operating procedures

REASONS

1-AIRBUS Guidance:

Airbus standard procedures specify that the thrust reduction altitude is first ,and acceleration altitude follows after typically at the same altitude or higher .

2-Safety consideration:

prolonged operations at takeoff thrust could lead to higher engine temperatures,potentially reducing margins for engine reliability in abnormal situations .

to avoid this issues thrust reduction and acceleration altitude should be carefully set according to SOP, Performance calculations and regulation.

3-Thrust reduction :

-the thrust reduction altitude marks the point where climb thrust is set from takeoff thrust to climb power which provides more efficient engine operation .

– prolonged climb in takeoff thrust beyond the typical thrust reduction altitude increase engine wear and fuel consumption,potentially reducing engine lifespan .

-Acceleration begins after thrust reduction to ensure sufficient climb gradient is maintained during the initial phase of flight .

4-Aircraft configurations and pilot work load:

pilots my need to intervene to manage the aircraft`s configuration and speed below the thrust reduction Acceleration as acceleration involves retracting flaps , slats and increasing the speed , which requires sufficient thrust to ensure safe performance .

5-Noise abatement NON-compliance :

operating in a noise -sensitive area maintaining takeoff thrust beyond the designated altitude might violate noise abatement procedures, potentially resulting in fines or operational restrictions.

thanks

CAPT/ AHMED SHEBL

FLIGHT INSTRUCTOR AND AIRLINE PILOT