USAir Flight 427
|Date||September 8, 1994|
Beaver County, Pennsylvania
|Aircraft type||Boeing 737-3B7|
|Flight origin||O'Hare International Airport|
|Stopover||Pittsburgh International Airport|
|Destination||West Palm Beach Int'l Airport|
USAir Flight 427 was a scheduled flight from Chicago's O'Hare International Airport to Pittsburgh International Airport, with a final destination of West Palm Beach, Florida. The flight crashed on Thursday, September 8, 1994, killing 132 on board. The Boeing 737-3B7 flying the route, registered N513AU, and previously registered as N382AU, was approaching runway 28R of Pittsburgh International Airport, located in Findlay Township, Allegheny County, Pennsylvania, which was at the time the largest hub for the airline. This was not the first Flight 427 to be involved in an incident in 1994. The other, TWA Flight 427, struck a smaller plane on takeoff, but did not crash.
Captain Peter Germano, 45, was hired by USAir in February 1981. First Officer Charles B. "Chuck" Emmett III, 38, was hired in February 1987 by Piedmont Airlines. Both the captain and first officer were regarded as excellent pilots. They were both very experienced, with approximately 12,000 flight hours and 9,119 flight hours, respectively. Flight Attendant Stanley Canty was hired in May 1989 by Piedmont Airlines. Flight Attendant April Slater was hired by Piedmont in March 1989. Flight Attendant Sarah Slocum-Hamley was hired in October 1988. Piedmont merged with USAir in 1989.
During its arrival into Pittsburgh, Flight 427 was sequenced behind Delta Airlines Flight 1083, a Boeing 727-200. At no time was Flight 427 closer than 4.1 miles to Delta 1083, according to radar data. During the approach, Flight 427 encountered wake turbulence from Delta 1083; the FAA, however, determined "the wake vortex encounter alone would not have caused the continued heading change that occurred after 1903:00." At 7:02:57 PM, there were three sudden thumps, clicking sounds, a louder thump, and then the 737 began to bank and roll to the left. The aircraft stalled, and rolled upside down. Germano exclaims, "Hold on" numerous times, as Emmett says "Oh shit" frequently. Germano says, "What the hell is this?" As air traffic control noticed Flight 427 descending without permission, Germano, keyed the mic and stated, "Four-twenty-seven, emergency!" The aircraft then rolled back upright, but after a few seconds on its side, the aircraft continued to roll while pitched nose down at the ground. Emmett shouted "What the hell!" and the Air Traffic Controller heard this. At 7:03:25 PM, the 737 slammed into the ground and exploded, in an 80 degree nose down position, while banked 60 degrees to the left, and traveling at 300 mph (480 km/h) in Hopewell Township, Beaver County, near Aliquippa, Pennsylvania, killing all 127 passengers and 5 crew members. The plane just barely missed the Green Garden shopping plaza, and the Aliquippa exit of the Beaver Valley Expressway (I-376, then PA-60), which was crowded with cars of people driving home from work, crashing onto a private gravel driveway and hillside on Pettita Lane in an area protected against trespassing. A memorial has been placed at the site of impact.
At the time of the crash, Flight 427 was the second deadliest accident involving a Boeing 737. As of 2012, it was the sixth deadliest. It was also the seventh deadliest aviation disaster in the history of the United States; as of 2012, it ranked ninth. In the period from 1989 to 1994, it was the company's fifth crash.
After the crash, USAir encountered difficulties in determining who was on board the aircraft. The company faced confusion regarding five or six passengers. Several employees of the U.S. Department of Energy had tickets to take later flights, but used them to fly on Flight 427. One young child was not ticketed. Due to the severity of the impact, the bodies of the passengers and crew were severely fragmented, leading investigators to declare the site a biohazard.
After one of the longest accident investigations in aviation history — lasting more than four and a half years — the concluding statement said:
The National Transportation Safety Board determines that the probable cause of the USAir flight 427 accident was a loss of control of the airplane resulting from the movement of the rudder surface to its blowdown limit. The rudder surface most likely deflected in a direction opposite to that commanded by the pilots as a result of a jam of the main rudder power control unit servo valve secondary slide to the servo valve housing offset from its neutral position and overtravel of the primary slide.
The exact mechanism of the failure was determined to be as follows: the servo valve remains dormant for much of the flight at high altitude, rendering it quite cold; the injection of hot hydraulic fluid (which has been in action throughout the plane all flight) was causing the valve to seize up. This seizing of the valve occurred in fewer than 1% of the lab tests, but perfectly explained all of the successive rudder malfunctions that caused the plane to crash.
The National Transportation Safety Board concluded that similar rudder problems caused the previously mysterious March 3, 1991 crash of United Airlines Flight 585 and the June 9, 1996, incident involving Eastwind Airlines Flight 517, both of which were Boeing 737s. As a result of the investigation, pilots were warned of and trained how to deal with insufficient aileron authority at an airspeed at or less than 190 knots (352 km/h), formerly the usual approach speed for a Boeing 737. Four additional channels of information — pilot rudder pedal commands — were incorporated into flight data recorders, while Boeing redesigned the rudder system on 737s and retrofitted existing craft until the affected systems could be replaced. The United States Congress also required airlines to deal more sensitively with the families of crash victims.
US Airways 427 is no longer a valid flight number on US Airways as of January 2011.
Flight 427 was the second fatal crash in a little over two months at the company (the other being USAir Flight 1016 at Charlotte-Douglas Airport in July 1994). The crashes contributed to the financial crisis USAir was experiencing at the time.
The accident was featured on the Discovery Channel Canada/National Geographic Channel television series Mayday (also known as Air Emergency or Air Crash Investigation in various countries) series 4 episode entitled "Hidden Danger" ("Mystery Crashes"), alongside United Airlines Flight 585 and Eastwind Airlines Flight 517.
- Boeing 737 rudder issues
- United Airlines Flight 585
- Eastwind Airlines Flight 517
- American Airlines Flight 1
- Northwest Airlines Flight 85
- "28 Seconds of Horror," Pittsburgh Tribune-Review
- "28 Seconds: The Mystery of USAir Flight 427 Part One: Zulu." 4. Retrieved on December 31, 2012.
- NTSB summary
- Remarks from acting NTSB Chairman, 2002
- Halvonik, Steve. "Disaster only one in a string of setbacks for troubled company." Pittsburgh Tribune-Review. Sunday September 5, 2004. Retrieved on January 1, 2012.
- "List of Crash Victims." Wilmington Morning Star. September 10, 1994. 4A. Google News (28 of 49). Retrieved on October 3, 2009.
- www.airliners.net - picture of N513AU painted in USAir's brown, orange, and red livery
- NTSB Accident Investigation Docket (Archive)
- AVweb article
- AVweb supplement
- Accident description at the Aviation Safety Network
- 28 Seconds Four-part article from the Saint Petersburg Times
- Boeing 737 Rudder Design Defect
- "Remembering Flight 427." Pittsburgh Tribune-Review. (Archive)
- Pre-Crash accident photos from Airliners.net
- Schaarsmith, Amy McConnell. "Mourners remember at 15th anniversary." Pittsburgh Post-Gazette. September 9, 2009.
- Memorial location
- Bill Adair, The Mystery of Flight 427: Inside a Crash Investigation, ISBN 1-58834-005-8
- Gerry Byrne, Flight 427: Anatomy of an Air Disaster, ISBN 0-387-95256-X