Aircraft upset

Aircraft upset is a dangerous condition in aircraft operations in which the flight attitude or airspeed of an aircraft is outside the normal bounds of operation for which it is designed. This may result in the loss of control (LOC) 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 as 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]

Overview

Loss of control as a factor in aviation accidents came into the spotlight with the 1994 crash of USAir Flight 427, which killed all 127 passengers and 5 crew members on board. In their report on the crash, the U.S. NTSB stated that prior to the crash they "...had issued a series of safety recommendations over a 24-year period, asking the FAA to require air carriers to train pilots in recoveries from unusual flight attitudes. Throughout this period, the Safety Board was generally not satisfied with the FAA’s responses to these recommendations; specifically, the Board disagreed with the FAA’s responses that cited the inadequacy of flight simulators as a reason for not providing pilots with the requested training. However, after the USAir Flight 427 accident and the October 31, 1994, ATR-72 accident involving American Eagle Flight 4184 near Roselawn, Indiana, the FAA issued guidance to air carriers, acknowledging the value of flight simulator training in unusual attitude recoveries and encouraging air carriers to voluntarily provide this training to their pilots."[5]

Some carriers did implement their own voluntary training programs, following those accidents, and the NTSB regarded those programs as "excellent."[5]

In October 1996, the NTSB issued a formal Safety Recommendation (A-96-120), which requested the FAA to require all airlines to provide simulator training for flight crews, which would enable them to recognize and recover from "unusual attitudes and upset maneuvers, including upsets that occur while the aircraft is being controlled by automatic flight control systems, and unusual attitudes that result from flight control malfunctions and uncommanded flight control surface movements."[1][5]

In 2004, the U.S. FAA issued its first Airplane Upset Recovery Training Aid.[6] The second revision of that document[7] was released in 2008 and is available at the FAA's website.[8]

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]

In 2009, the Royal Aeronautical Society formed a new group of experts, who will form documentation to allow better simulations of aircraft upset conditions, and thus better training programs.[9]

Detailed definition

From: The FAA's Pilot Guide to Airplane Upset Recovery.[3][7]

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:

However, the definition of an upset is disputable and changes between documents and training programs. The Royal Aeronautics Society states: “An upset is not necessarily a departure from controlled flight (i.e. a stall/spin) but it also includes abnormal attitudes and gross over/under-speed conditions.”[10] Calspan, which has been involved with upset research and training since teaming with NASA in 1997, holds that the generally accepted industry guidelines are incomplete in that they only take into consideration aircraft attitude and airspeed. Jet Upset is defined by Calspan as an airplane unintentionally exceeding the parameters normally experienced in line operations or a control failure or disturbance that alters the normal response of the airplane to pilot input such that the pilot must adopt an alternate control strategy to regain and sustain controlled flight. Normal flight parameters are defined as pitch attitude within:

This expanded definition is intended to more fully capture the maneuvers, events, conditions, and circumstances that the record has shown lead to LOC.[11]

Jet upset

The phrase jet upset refers to accidents and incidents (some crashed and some recovered, usually with significant damage to the structure), where a jet airliner was "upset" and ended up in a high-speed dive. That phenomenon was almost unknown in the days of piston-driven propeller airliners, which is why those accidents were referenced as "jet" upsets: because it was a repeated phenomenon that was unique to jet airliners, with swept-back wings, jet engines and movable horizontal stabilizers, none of which were found on the piston/propeller airliners. With the phasing out of piston-driven propeller airliners, that phrase has gradually given way to "loss of control-inflight," which includes, but is not limited to, the upset/high-speed dive type of accidents. The term jet upset was most heavily used in the 1960s and 1970s as the phenomenon was not well understood and was still being researched.[12] Contemporary authors tend to group the phenomenon under loss of control.[13]

There have been a variety of causes and contributing factors, in past jet upset accidents:

Related accidents


See also

References

 This article incorporates public domain material from the Federal Aviation Administration document "http://www.faa.gov/other_visit/aviation_industry/airline_operators/training/media/AP_UpsetRecovery_Book.pdf".

  1. 1 2 3 4 5 "Getting control of LOC". Flightglobal. January 27, 2009. Retrieved December 1, 2015.
  2. 1 2 http://gltrs.grc.nasa.gov/reports/2000/TM-2000-209810.pdf
  3. 1 2 3 Note: Partial text copied from referenced FAA or NASA document. As a public work of the U.S. Government, the document is in the public domain and has no copyright.
  4. http://www.nastarcenter.com/news/view.php?volume=2&issue=4&article=101
  5. 1 2 3 USAir Flight 427 Accident report, pg. 283
  6. http://www.faa.gov/other_visit/aviation_industry/airline_operators/training/media/Appendix%203-E_HighAltOperations.ppt Archived February 27, 2009, at the Wayback Machine.
  7. 1 2 http://www.faa.gov/other_visit/aviation_industry/airline_operators/training/media/AP_UpsetRecovery_Book.pdf U.S. FAA Airplane Upset Recovery Training Aid, Revision 2, 443 pages, 25.8 MB
  8. http://www.faa.gov/other_visit/aviation_industry/airline_operators/training/index.cfm
  9. Croft, John (2009-11-14). "Upset training group to hold first meeting". Air Transport Intelligence news. Archived from the original on 19 November 2009. Retrieved 2009-11-15. The devices are not currently required to perform accurately in the realm outside of the flight or wind tunnel test points, nor are pilots currently trained to fly in those conditions.
  10. Aeroplane Upset Recovery Training, History, Core Concepts & Mitigation (PDF). London: Royal Aeronautics Society. 2010. Retrieved December 17, 2014.
  11. Priest, James; Ernisse, Brian; McMahon, Ryan (August 2010). "Comprehensive In-Flight Simulation Based Advanced Maneuver & Upset Recovery Training Study". AIAA Guidance, NAvigation, and Control Conference. doi:10.2514/6.2010-8009. Retrieved December 17, 2014.
  12. Books listing for jet upset term
  13. Books listing for loss of control term
  14. Aircraft Accident Report|Pan Am B707, Over The Atlantic, between London and Gander, February 3, 1959
  15. Aircraft Accident Report|NWA B720B, Everglades, near Miami, February 12, 1963
  16. Turbulence Penetration Study, pgs. 18 & 19|UAL B720, Upset near O'Neal Nebraska, July 12, 1963
  17. NTSB Report China Airlines Flight 006

Further reading

External links

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