It always takes a chain of events to cause a crash. In this case, it took wake turbulence from a Delta 727, the startling of the pilots, the fact that the plane was flying at the crossover point, the uniqueness of the valve, the jam and reversal, and the mistake of pulling back on the stick. If any one of those things had been different, the plane would not have crashed.
“What the hell is this?” Captain Peter Germano had said on the cockpit voice recorder as USAir 427 plunged toward the ground. Haueter thought he finally knew the answer.�