Originally Posted by
HeavyMetallist
Could somebody explain to a simple engineer how an air temperature "spike" would cause the aircraft to go into an overspeed protection? I've seen this theory posited to explain an automatic pull-up, but I can't see why the aircraft would, either correctly or erroneously, "think" it was overspeeding.
It is important in many aircraft to avoid stresses due to shockwaves forming on the aircraft surfaces due to approaching the speed of sound. The speed of sound is dependent on the air pressure _and_ the temperature see
Mach Number
So a sudden change up in temperature can convince the automatics that the aircraft is too close to the speed of sound and damaging shockwaves may be forming on the airframe and control surfaces. The automatics then do their best to recover back to below the limiting Mach No. The quickest way to do that is to pull up.
Just as an addition- going too fast and getting shockwaves build on various surfaces can lead to other interesting effects such as control reversals which could lead to dangerous effects.