USAir Flight 427
Accident | |
---|---|
Date | September 8, 1994 |
Summary | Loss of control due to rudder hardover[1] |
Site | Hopewell Township, Beaver County, Pennsylvania, United States 40°36′14″N 80°18′37″W / 40.60393°N 80.31026°W |
Aircraft | |
Aircraft type | Boeing 737-3B7 |
Operator | USAir |
IATA flight No. | US427 |
ICAO flight No. | USA427 |
Call sign | USAIR 427 |
Registration | N513AU[2] |
Flight origin | O'Hare International Airport |
Stopover | Pittsburgh International Airport |
Destination | Palm Beach International Airport |
Occupants | 132 |
Passengers | 127 |
Crew | 5 |
Fatalities | 132 |
Survivors | 0 |
USAir Flight 427 was a scheduled flight from
After the longest investigation in the history of the
Aircraft and crew
Aircraft
The aircraft involved was a
Crew
The flight crew consisted of Captain Peter Germano, 45, who was hired by USAir in February 1981, and First Officer Charles B. "Chuck" Emmett III, 38, who was hired in February 1987 by
Crash
In its arrival phase approaching Pittsburgh, Flight 427 was sequenced behind Delta Air Lines Flight 1083, a Boeing 727-200. At no time was Flight 427 closer than 4.1 miles (6.6 km) to Delta 1083, according to radar data.[1]: 2 Flight 427 was on approach at 6,000 feet (1,800 m) altitude, at flaps 1 configuration, and at approximately 190 knots (220 mph; 350 km/h).
At 19:02:57, the aircraft entered the
As the stick shaker activated, Germano exclaimed "Hold on!" numerous times,[1]: 138 while Emmett, under physical exertion, said, "Oh shit!"[1]: 143 Germano exclaimed, "What the hell is this?"[1]: 6 As air traffic control noticed Flight 427 descending without permission, Germano keyed the mic and stated, "Four-twenty-seven, emergency!"[1]: 6 Because the mic remained keyed for the rest of the incident, the ensuing exclamations in the cockpit were heard in the tower at Pittsburgh. The aircraft continued to roll while pitched nose-down at the ground. Trying to counteract sharply rising G-forces, Germano yelled "Pull!" three consecutive times before screaming, during which Emmett stated "God, no" seconds before impact. Pitched 80° nose-down and banked 60° left while traveling at approximately 300 mph (260 kn; 480 km/h), the 737 slammed into the ground and exploded at 19:03:25 in Hopewell Township, Beaver County,[3] near Aliquippa, approximately 28 seconds after entering the wake turbulence.
At the time of the accident, many people had gathered at a nearby soccer field, for evening soccer practice. These people witnessed the crash of the aircraft, and described the plane as suddenly falling out of the sky.
Investigation
The
Both the cockpit voice recorder (CVR) and
Reading the control-yoke data from the FDR revealed that the pilots made a crucial error by pulling back on the yoke throughout the dive, with the
Investigators later discovered that the recovered accident rudder power control unit was much more sensitive to bench tests than other new such units. The exact mechanism of the failure involved the servo valve, which remains dormant and cold for much of the flight at high altitude, seizing after being injected with hot hydraulic fluid that has been in continuous action throughout the plane. This specific condition occurred in fewer than 1% of the lab tests but explained the rudder malfunction that caused Flight 427 to crash. The jam left no trace of evidence after it occurred, and a Boeing engineer later found that a jam under this controlled condition could also lead to the slide moving in the opposite direction than that commanded. Boeing felt that the test results were unrealistic and inapplicable given the extremes under which the valve was tested.[13][11] It stated that the cause of the rudder reversal was more likely psychological and likened the event to a circumstance in which an automobile driver panics during an accident and accidentally presses on the gas pedal rather than the brake pedal.[14][11] The FAA's official position was that sufficient probable cause did not exist to substantiate the possibility of rudder system failure.[15]
After the longest accident investigation in NTSB history — lasting more than four and a half years — the NTSB released its final report on March 24, 1999.[1][16] The NTSB concluded that the accident was the result of mechanical failure:
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.[a] 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.[1]: ix
The NTSB concluded that similar rudder problems had 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 Boeing 737s.[1]: 292–295 The final report also included detailed responses to Boeing's arguments about the causes of the three accidents.
Aftermath
At the time of the crash, Flight 427 was the second-deadliest accident involving a Boeing 737 (all series); as of 2024, it now ranks as the ninth-deadliest. It was also the seventh-deadliest aviation disaster in the history of the United States, and the deadliest in the U.S. involving a 737; as of 2024, it ranks eleventh.[17] The accident marked USAir's fifth crash in the period from 1989 to 1994.[9] The Commonwealth of Pennsylvania spent approximately $500,000 in recovery and cleanup for the accident site.[8]
The FAA disagreed with the NTSB's probable-cause verdict and Tom McSweeney, the FAA's director of aircraft certification, issued a statement on the same day on which the NTSB report was issued that read: "We believe, as much as we have studied this aircraft and this rudder system, that the actions we have taken assure a level of safety that is commensurate with any aircraft."[18]
However, the FAA changed its attitude after a special task force, the Engineering Test and Evaluation Board,[14] reported in July 2000 that it had detected 46 potential failures and jams in the 737 rudder system that could have catastrophic effects. In September 2000, the FAA announced that it wanted Boeing to redesign the rudder for all iterations of the 737, affecting more than 3,400 aircraft in the U.S. alone.[14]
USAir submitted to the NTSB that pilots should receive training with regard to a plane's crossover speed and recovery from full rudder deflection.
Following the airline's response to the Flight 427 accident, the United States Congress required that airlines "provide families of crash victims courteous and sensitive treatment and assistance with the various needs that accompany an accident".[23][24]
USAir ceased using Flight 427 as a flight number. The crash was the second fatal USAir crash in just over two months, following the July 2 Flight 1016 accident at Charlotte-Douglas International Airport that killed 37. The crashes contributed to the financial crisis that USAir was experiencing at the time.[25]
Memorial
The crash site itself, located near the Aliquippa exit of I-376, is located on private property. The road that is needed to access the site is accessible only to 427 Support League and Pine Creek Land Conservation Trust members.[26] Three tombstones are located at the Sewickley Cemetery, 10 miles (16 km) from the site of the crash and within the flight path of USAir 427.[27]
In popular culture
- The New Yorker published an article on the Flight 427 investigation on July 28, 1996. "Searching for the Cause of a Catastrophic Plane Crash" was written by Jonathon Harr.
- The Discovery Channel Canada / National Geographic TV series Mayday– also known as Air Disasters – dramatized the crash of Flight 427 and the subsequent 737 rudder investigation in the 2007 episode "Hidden Danger".
- The accident was dramatized in the episode "Fatal Flaws" of Why Planes Crash.
See also
Similar incidents
- United Airlines Flight 585
- Eastwind Airlines Flight 517
- American Airlines Flight 1
- Northwest Airlines Flight 85
- American Airlines Flight 587
- Indonesia AirAsia Flight 8501
References
Informational notes
- ^ blowdown limit is the maximum deflection that a control surface is capable of reaching under given flight conditions
Citations
- ^ a b c d e f g h i j k l m n o p q Aircraft Accident Report – Uncontrolled Descent and Collision With Terrain, USAir Flight 427, Boeing 737-300, N513AU, Near Aliquippa, Pennsylvania, September 8, 1994 (PDF). National Transportation Safety Board. March 24, 1999. NTSB/AAR-99/01. Archived (PDF) from the original on March 4, 2016. Retrieved January 17, 2016.
- ^ "FAA Registry (N513AU)". Federal Aviation Administration.
- ^ "28 Seconds of Horror," Pittsburgh Tribune-Review
- ^ a b Bertorelli, Paul (October 19, 1997). "USAir 427: US Airways' View of the Accident – AVweb Features Article". Avweb.com. Archived from the original on November 25, 2016. Retrieved December 3, 2016.
- ^ "28 Seconds: Roxie, Trixie and the fat guy 3". Sptimes.com. September 8, 1994. Archived from the original on August 21, 2016. Retrieved December 3, 2016.
- ^ Federal Aviation Administration (September 8, 1994). "Lessons Learned". Lessonslearned.faa.gov. Archived from the original on December 20, 2016. Retrieved December 3, 2016.
- National Geographic Channel.
- ^ a b "US Air Flight 427 Crash Near Aliquippa, Pennsylvania" (PDF). Federal Aviation Administration. Archived from the original (PDF) on September 24, 2017. Retrieved September 23, 2017.
- ^ a b "28 Seconds: The Mystery of USAir Flight 427 Part One: Zulu Archived September 12, 2012, at the Wayback Machine." Retrieved on December 31, 2012.
- Wilmington Morning Star. September 10, 1994. 4A. Google News(28 of 49). Retrieved on October 3, 2009.
- ^ ISBN 1-58834-005-8.
- ^ "Lessons Learned". Federal Aviation Administration. November 2, 2016. Archived from the original on November 2, 2016.
- ^ "Business - Expert Panel May Have Key To Which 737S Are Most At Risk - Seattle Times Newspaper". community.seattletimes.nwsource.com. Archived from the original on September 28, 2015. Retrieved December 19, 2012.
- ^ ISBN 0-387-95256-X.
- ^ "SUBMISSION OF FEDERAL AVIATION ADMINISTRATION, USAir Flight 427 Crash Near Aliquippa, Pennsylvania" (PDF). Archived from the original (PDF) on February 11, 2017. Retrieved September 23, 2017.
- ^ NTSB Office of Public Affairs (March 24, 1999). "NTSB Concludes Longest Investigation in History; Finds Rudder Reversal was Likely Cause of USAIR Flight 427, A Boeing 737, Near Pittsburgh in 1994" (Press release). National Transportation Safety Board. Archived from the original on April 21, 2016. Retrieved July 18, 2016.
- ^ Ranter, Harro. "ASN Aircraft accident Boeing 737-3B7 N513AU Aliquippa, PA". Aviation Safety Network. Archived from the original on June 16, 2013. Retrieved May 27, 2013.
- ISBN 0-387-95256-X.
- ^ "The Seattle Times: Safety at issue: the 737". Old.seattletimes.com. October 29, 1996. Archived from the original on June 21, 2017. Retrieved December 3, 2016.
- ^ "Boeing: News Feature -- 737 Rudder Enhancements -- Enhanced Rudder System". January 12, 2008. Archived from the original on January 12, 2008.
- ^ "NTSB Concludes Longest Investigation in History; Finds Rudder Reversal was Likely Cause of USAIR Flight 427, A Boeing 737, Near Pittsburgh in 1994". Ntsb.gov. National Transportation Safety Board. March 24, 1999. Archived from the original on February 28, 2017. Retrieved July 22, 2017.
- ^ "Fatal Flaws". Why Planes Crash. Season 2. 2016. MSNBC.
- ^ Gough, Paul J. (September 7, 2014). "Families of USAir 427 victims helped alter course of aviation". Pittsburgh Business Times. Archived from the original on October 12, 2014. Retrieved March 9, 2021.
- ^ "Remarks from acting NTSB Chairman, 2002". Archived from the original on September 25, 2012.
- ^ Halvonik, Steve (September 5, 2004). "Disaster only one in a string of setbacks for troubled company". Pittsburgh Tribune-Review. Archived from the original on May 20, 2007. Retrieved January 1, 2012.
- ^ "Flight 427 Air Disaster Support League". September 24, 2012. Archived from the original on November 23, 2021. Retrieved February 6, 2022.
- ^ Adair, Bill (April 9, 1999). "28 SECONDS // The Mystery of USAir Flight 427". tampabay.com. Tampa Bay Times. Archived from the original on February 7, 2022. Retrieved February 6, 2022.
External links
- NTSB Accident Report - Copy at Embry-Riddle Aeronautical University
- NTSB Accident Investigation Docket (Archive)
- CVR Transcript (Archive)
- FDR Transcript (Archive)
- Boeing's report to the NTSB (Archive)
- ALPA's report to the NTSB (Addendum) (Archive) (Addendum archive)
- Accident description at the Aviation Safety Network
- Photos of the accident aircraft from Airliners.net
- 25 years ago, USAir Flight 427 crashed near Hopewell despite perfect conditions
- Air traffic control recordings of Flight 427 on YouTube