There was a multitude of clues, but one of the key points that led to an ultimate resolution was a radar track that showed flight 427 crossing the wake of a 727 at the exact moment when things started to go wrong. It could be a demanding and uncomfortable job, but most investigators knew that the results of the investigation would make things safer, and they considered it a failure when they could not determine a cause, as in the case of the Colorado Springs 737 crash. The NTSB is charged with overseeing investigations and making a final determination as to the cause of transportation accidents. One of the criticisms of the NTSB had been the 'party' system that permitted each agency or group its bias: Boeing (which had a desire to implicate the pilots and clear the airplane), ALPA (the Airline Pilots Association that had a special interest in clearing the pilots), USAir (that would have been happy to blame anyone other than itself), and the FAA (an agency often accused of having a contradictory role: promoting aviation yet making it as safe as possible). In the end, this investigation also resulted in computer data that lead to a determination that something similar happened in the crash of a United 737 over Colorado Springs.Ĭrash investigations throw together a multitude of people, each with a particular agenda or point of view, and places them under extreme pressure.

The problem was rudder movement in the wrong direction, opposite to what was indicated by the rudder pedals. It was Boeing engineers who discovered the peculiar flaw in the special and unique design of the power control unit (PCU) that caused the rudder to go into hard over - a full application of the rudder, the large movable section in the plane's tail that in a 737 is used mostly during crosswind landings.

Adair has painstakingly reconstructed the investigation into the crash of a Boeing 737, one of the world's safest airplanes. It's ironic, but crashes are making flying safer, and this book again demonstrates Henry Petroski's (my favorite civil engineer) aphorism that we learn more from failure than we do from success.

The Mystery of Flight 427 by Bill Adair