I have a question for those of you that drive the big birds. What do you think of the taxi-into-the-air technique (using less than full power at takeoff if there's enough runway available)?
It would seem to me that using full power on EVERY takeoff would result in better chances should something catastrophic happen around V1, as you'd have more runway in front of you.
We use RTOP (Reduced Take-off Power) in the Q. It's not used for every takeoff, and we can't always reduce the same amount, it's all based on the current conditions (as R&W explained). Even at reduced power, we still have enough excess power to get out of almost any potential problem situation. NTOP (Normal T/O Power) is 96% Torque. The most we can reduce is to 83% Torque. Anything less than about 7000 feet of runway, any contamination on the runway, or if we're launching into icing conditions and we'll probably be at NTOP. There's still a more than decent safety margin built in to reduced power take offs.
If an engine fails, even if we're using reduced power, the computer automatically bumps the operating engine up to MTOP (Max T/O Power) at 100% Torques. If that's still not enough, at any time, we can push the power levers into the over-travel range (aka the oh $h!T range) and get up to 106% Torque.
Long story short, reduced power takeoffs are still using a lot of power, and we always have the option of more at a moments notice. What's more, they save gas and increase the service life of the engine.
If you want to see a truly intense reduced power t/o, watch the MD-80s at LGA. When they use derated thrust, they don't rotate until they've passed the 1000 footers on the
far end of the runway. But even if they used MTOP, on such a short runway, a late abort would put them either in the drink or in the Bronx.
