On September 8, 1994, USAir Flight 427 — a Boeing 737-300, registration N513AU, flying from Chicago O’Hare to Pittsburgh with an onward leg to West Palm Beach — was lining up to land at Pittsburgh International Airport, then the airline’s largest hub. Seconds after crossing the wake of the airliner ahead of it on the approach, at about 7:03 p.m., the jet rolled suddenly to the left, pitched down, and dived into a wooded hillside in Hopewell Township, Beaver County, some six miles from the airport. All 132 people aboard were killed: 127 passengers, Captain Peter Germano, First Officer Charles B. “Chuck” Emmett III, and three flight attendants. It remains the deadliest air disaster in Pennsylvania history.
The crash defied explanation for years, and it did not stand alone: investigators recognised the same signature in the 1991 crash of United Airlines Flight 585 in Colorado and in a frightening 1996 incident involving Eastwind Airlines Flight 517, both also Boeing 737s. The National Transportation Safety Board’s investigation ran more than four and a half years — the longest in its history to that point — before the Board adopted its final report, NTSB/AAR-99/01, on March 24, 1999.
The Board determined that the probable cause was a loss of control as the rudder moved to its blowdown limit, most likely in the direction opposite to the pilots’ command, because the main rudder power control unit’s servo valve had jammed — its secondary slide stuck offset from neutral and its primary slide driven into overtravel. At the flight’s low altitude, recovery was impossible. The finding led Boeing to redesign the 737’s rudder control system with a redundant backup, and the improved system was retrofitted across the worldwide 737 fleet.
A memorial at the crash site in Hopewell Township is dedicated to the 132 passengers and crew of Flight 427.