Originally Posted by
TopBunk
What circumstances would require you to need extra thrust?
To gain extra ROC you can trade airspeed/Mach for a (short) while. Anything else could and maybe should require a call to ATC saying 'unable' or a request for descent.
TopBunk at this point I only come out from scenario that I am accidentally flying into a missile area where I have to reach certain Altitude to avoid those missile. For example I am cruize at FL 290, and as per notam Minimum flying is FL 360, where deviate is not an option.
Sorry for the confusion, I am just curious. Not planning to experience it in real life.