Aircraft upset
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Aircraft upset is a dangerous condition in aircraft operations which may result in the loss of control of the aircraft, and sometimes the total loss of the aircraft itself.[1] Loss of control may be due to turbulent weather, pilot disorientation, or a system failure.[2][3]
The U.S. NASA Aviation Safety Program[2][3] defines upset prevention and upset recovery to prevent loss of control accidents due to aircraft upset after inadvertently entering an extreme or abnormal flight attitude.
A Boeing-compiled list determined that 2,051 lives were lost in 22 accidents in the years 1998–2007 due to LOC accidents.[1] NTSB data for 1994–2003 count 32 accidents and more than 2,100 lives lost worldwide.[4]
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[edit] Overview
After the fatal 1994 crash of USAir Flight 427, the U.S. NTSB recommended in 1996 to train pilots "to respond to sudden, unusual or unexpected aircraft upsets".[1]
In 2004, the U.S. FAA first issued the Airplane Upset Recovery Training Aid[5]. Revision Two was released in 2008 and is freely available on the FAA's website.[6]
New FAA rules are expected to be finalized in 2010, requiring specific training for pilots to recover from aircraft upset incidents.[1] New training programs may be known under the term advanced maneuver - upset recovery training (AM-URT).[1]
[edit] Detailed definition
The U.S. FAA defines aircraft upset in the Pilot Guide to Airplane Upset Recovery[6][3]. An airplane upset is defined as an airplane in flight unintentionally exceeding the parameters normally experienced in line operations or training. In other words, the airplane is not doing what it was commanded to do and is approaching unsafe parameters. While specific values may vary among airplane models, the following unintentional conditions generally describe an airplane upset:
- Pitch attitude greater than 25 deg, nose up.
- Pitch attitude greater than 10 deg, nose down.
- Bank angle greater than 45 deg.
- Within the above parameters, but flying at airspeeds inappropriate for the conditions.
It should be emphasized that recovery to a stabilized flight path should be initiated as soon as a developing upset condition is recognized. This preventive action may alleviate what might have become a more serious event.
[edit] Jet upset
A subtype of aircraft upset is jet upset, although some writers may confusingly use the terms interchangeably. Three elements are necessary for jet upset to occur:
- High altitude wave phenomenon
- Outdated technology - airfoils with abrupt mach tuck characteristics and autopilots without built-in protections and primitive servos
- Crew inattention — as little as 15 seconds.
In a jet upset, the aircraft enters rising high altitude wave conditions with autopilot on and full speed trim follow up trimming nose down. Shortly after encountering wave down action, autopilot reaches force limits and disconnects. The crew is behind the aircraft, and the aircraft exceeds critical mach with mach tuck aggravating problem. All jets have altitude/pitch/speed combinations that are unrecoverable. Through the use of drag devices or pitch/power coupling, the aircraft may respond. Control forces become very high and even trimmable stabs may not have ability to increase pitch of aircraft.
[edit] Related incidents
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- 1972-06-12 American Airlines Flight 96
- 1974-03-03 Turkish Airlines Flight 981
- 1979-04-04 TWA Flight 841 (1979)
- 1985-08-12 Japan Airlines Flight 123
- 1989-07-19 United Airlines Flight 232
- 1994-06-30 1994 A330 test flight crash
- 1994-09-08 USAir Flight 427
- 1994-10-31 American Eagle Flight 4184
- 1994-12-11 Philippine Airlines Flight 434
- 1996-06-09 Eastwind Airlines Flight 517
- 2001-11-12 American Airlines Flight 587
- 2003-11-22 DHL Baghdad incident
- 2005-03-06 Air Transat Flight 961
- 2009-02-12 Continental Connection Flight 3407
[edit] See also
[edit] External links
[edit] References
Moynahan, Brian (1978). Airport International. Pan. p. 184.
- ^ a b c d e http://www.flightglobal.com/articles/2009/01/27/321563/getting-control-of-loc.html
- ^ a b http://gltrs.grc.nasa.gov/reports/2000/TM-2000-209810.pdf
- ^ a b c Note: Partial text copied from referenced NASA document. As a public work of the U.S. Government, the document is in the public domain and has no copyright.
- ^ http://www.nastarcenter.com/news/view.php?volume=2&issue=4&article=101
- ^ http://www.faa.gov/other_visit/aviation_industry/airline_operators/training/media/Appendix%203-E_HighAltOperations.ppt
- ^ a b http://www.faa.gov/other_visit/aviation_industry/airline_operators/training/index.cfm
