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Old 25th May 2009, 19:48
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Mad (Flt) Scientist
 
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Originally Posted by botaxgendeng
according the fctm, just be carefull if you push toga when you take off with derated since the vmca/vmcg will be higher than v2.
That just doesn't sound right.

My understanding of the usual situation ( at least for FADEC types, which the 777 surely is) is that you will get max rated thrust at TOGA, but if you've selected a derate (as opposed to just flexing) then you still won't get any more than the derated max, not the absolute (non derated) thrust.

Derate is sometimes described as being the equivalent of actually bolting on a lower thrust engine, and accepting both the gains and losses of being now a different engine/airframe combination (lower VMCs but lower max thrust too).

Just being able to revert to full thrust with a press of a switch seems wrong - and bordering on non certifiable.
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