Is the takeoff power always maximum?

Question

I used to think that for commercial aircraft from Airbus, Boeing, Embraer, etc., the take off power was always maximum and selected by the TOGA selection on the thrust levers. But I have been told that some companies would lower the takeoff power to save money (at the expense of a longer take-off length).

So the question is: for regional, continental, and long-haul aircraft, is the takeoff power always maximum or can it be adjusted depending on the configuration? And can lowering takeoff power allow savings?

Answer 1

Takeoff power is almost never maximum engine power.

1. Maximum power affects engine life as it brings significant wear to the engine. IIRC, if max power is used on takeoff, the crew must log an entry in the logbook to notify maintenance.
2. Turbo-fans produce a lot of power. If you require max power to takeoff, you better double-check your numbers, or you're operating with a pretty narrow margin.

The reality is the reverse: airlines love to do low power takeoffs, and they avoid a high power takeoff as much as practical. Occasionally, a condition such as high ambient temperature (resulting in high pressure altitude), heavy load, obstacle on departure path may demand a max power takeoff. Possible wind shear may also prompt the crew to select a higher takeoff power.

Answer 2

Is the takeoff power always maximum?

No, unless it is required.

Disadvantages for using full power on takeoff is higher fuel consumption, noise, and engine wear.

Instead, takeoff performance is calculated and the appropriate thrust setting is used.

You need lower setting if:

1. runway is long
2. no obstacle to clear during climb
3. runway is dry
4. temperature is low
5. headwind is fast
6. airport is low (altitude)

All the above would increase your allowed payload and/or fuel load, and/or allow reduced thrust.