...Aviation experts were perplexed, saying it was rare for a plane to crash because of depressurization. "Although there are precedents for both pilots losing consciousness at the controls of the aircraft in the past, for it to happen on a large airliner like a Boeing 737, with all the backup systems they have there, does seem to be really quite extraordinary," said Kieran Daly, editor of Air Transport Intelligence.... Airliners are pressurized by a system that draws air from the engines, which compress air for internal use. A valve at the back of the plane determines how fast air is...
