Thanks for the replies.
I would think that if there is an engine failure at V1, the thrust most likely won't get advanced(at least I haven't seen it done in the sim and there are not many real world actual events to analyse).
But there may be other reasons to push the thrust way up. Maybe a feeling at higher speeds that acceleration is not normal, or a object on the runway or the end of the runway itself or windshear. Of course, using your emergency authority to advance the thrust is the obvious thing to do. The chance of having an engine failure at this time is extremely small, especially with EEC's that will prevent an overboost.
It just seems that after reading the warning that you are not to advance the thrust beyond the certified takeoff limit due to potential controllability issues could make some people hesitant to do so even when they should do so and therefore if max assumed temp thrust reduction is used first and most frequently then it could be possible to prevent a potential belief that you must not advance the thrust above the takeoff limit.
With overboost protection and all engines operating, I don't see much adverse risk to firewalling the thrust levers on normally operating engines when an urgent situation requires it.
So I wonder why the Boeing software does derate first. Maybe for displayng maximum payload capability in the quickest manner.
Last edited by JammedStab; 28th Nov 2012 at 11:47.