Why do airplanes become unstable after sudden depressurization?

Answer 1

Most depressurization effects you see in the movies are just Hollywood effects - two minor problems occur, one is thrust from escaping air and the other is a change in airflow from whatever opening created the depressurization - the real problem is not the aircraft but the pilot and passengers - pressurization allows people to breathe a normal amount of oxygen - sudden depressurization can cause severe lack of oxygen and eventual loss of consciousness - therefore the pilots may not be able to adequately control the aircraft - of course it really depends on how badly the aircraft was damaged - if pressure loss is due to losing the tail section that's bad but its more than just losing pressure.

AnswerSudden depressurization, more commonly known as explosive decompression, will not affect the controllability of the aircraft other than, perhaps, through the effects of the rapid depressurization itself. In other words, while there could be some physical disruption of controllability caused by debris flying about the cabin, or possibly structural damage to the airframe resulting from whatever caused the decompression in the first place, once the pressurization has equalized, the aircraft will continue to function as advertised.

A classic example of this is the Aloha Airlines 737 that lost the forward part of the fuselage due to a stress fracture, it experienced a rapid decompression at 24,000 feet, and went on to make a safe landing. See the link to pictures below.