Jet upset
Encyclopedia
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. Loss of control may be due to turbulent weather, pilot disorientation, or a system failure.
The U.S. NASA
Aviation Safety Program 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. NTSB data for 1994–2003 count 32 accidents and more than 2,100 lives lost worldwide.
, the U.S. NTSB "...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."
Some carriers did implement their own voluntary training programs, following those accidents, and the NTSB regarded those programs as "excellent."
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."
In 2004, the U.S. FAA issued its first Airplane Upset Recovery Training Aid. The second revision of that document was released in 2008 and is available at the FAA's website.
New FAA rules are expected to be finalized in 2010, requiring specific training for pilots to recover from aircraft upset incidents. New training programs may be known under the term advanced maneuver - upset recovery training (AM-URT).
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.
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:
Recovery to a stable flight path should be initiated as soon as a developing upset condition is recognized. This preventive action may alleviate what might otherwise develop into a very serious event.
There have been a variety of causes and contributing factors, in past jet upset accidents:
The U.S. NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
Aviation Safety Program 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. NTSB data for 1994–2003 count 32 accidents and more than 2,100 lives lost worldwide.
Overview
Prior to the fatal 1994 crash of USAir Flight 427USAir Flight 427
US Air Flight 427 was a scheduled flight from Chicago's O'Hare International Airport to Pittsburgh, with a final destination of West Palm Beach, Florida...
, the U.S. NTSB "...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
USAir Flight 427
US Air Flight 427 was a scheduled flight from Chicago's O'Hare International Airport to Pittsburgh, with a final destination of West Palm Beach, Florida...
accident and the October 31, 1994, ATR-72 accident involving American Eagle Flight 4184
American Eagle Flight 4184
American Eagle Flight 4184 was an American Eagle ATR 72 that crashed after flying into unknown icing conditions on October 31, 1994. Control was lost and all aboard were killed.-History:...
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."
Some carriers did implement their own voluntary training programs, following those accidents, and the NTSB regarded those programs as "excellent."
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."
In 2004, the U.S. FAA issued its first Airplane Upset Recovery Training Aid. The second revision of that document was released in 2008 and is available at the FAA's website.
New FAA rules are expected to be finalized in 2010, requiring specific training for pilots to recover from aircraft upset incidents. New training programs may be known under the term advanced maneuver - upset recovery training (AM-URT).
In 2009, the Royal Aeronautical Society
Royal Aeronautical Society
The Royal Aeronautical Society, also known as the RAeS, is a multidisciplinary professional institution dedicated to the global aerospace community.-Function:...
formed a new group of experts, who will form documentation to allow better simulations of aircraft upset conditions, and thus better training programs.
Detailed definition
From: The FAA's Pilot Guide to Airplane Upset Recovery.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 airspeedAirspeedAirspeed is the speed of an aircraft relative to the air. Among the common conventions for qualifying airspeed are: indicated airspeed , calibrated airspeed , true airspeed , equivalent airspeed and density airspeed....
s inappropriate for the conditions.
Recovery to a stable flight path should be initiated as soon as a developing upset condition is recognized. This preventive action may alleviate what might otherwise develop into a very serious event.
Jet upset
The phrase jet upset refers to past accidents (some crashed and some recovered, usually with significant damage to the structure), where a jet airliner was "upset" and went into a high 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 phenomena 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," which includes, but is not limited to, the upset/high-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. Contemporary authors tend to group the phenomenon under loss of control.There have been a variety of causes and contributing factors, in past jet upset accidents:
- February, 1959: A Pan American B-707Boeing 707The Boeing 707 is a four-engine narrow-body commercial passenger jet airliner developed by Boeing in the early 1950s. Its name is most commonly pronounced as "Seven Oh Seven". The first airline to operate the 707 was Pan American World Airways, inaugurating the type's first commercial flight on...
upset and went into a high dive while cruising over the Atlantic at flight levelFlight levelA Flight Level is a standard nominal altitude of an aircraft, in hundreds of feet. This altitude is calculated from the International standard pressure datum of 1013.25 hPa , the average sea-level pressure, and therefore is not necessarily the same as the aircraft's true altitude either...
350. Control was not recovered until reaching 6,000 ft. After landing safely at Gander, extensive structural damage was found, but there were only a few minor injuries. The Captain was in the cabin when the autopilotAutopilotAn autopilot is a mechanical, electrical, or hydraulic system used to guide a vehicle without assistance from a human being. An autopilot can refer specifically to aircraft, self-steering gear for boats, or auto guidance of space craft and missiles...
disconnected without adequate warning to the First Officer, who was distracted with a "howgozit" report form. It wasn't until the first officer felt the stall buffet that he realized they were descending rapidly and about to turn upside down. He was unable to level the wings. Fortunately, the Captain was able to return to the cockpit strap into his seat while enduring significant G-forces. He took over the controls, leveled the wings and pulled out of the dive.
- February, 1963: Northwest Orient Airlines Flight 705Northwest Orient Airlines Flight 705Northwest Orient Airlines Flight 705 was a scheduled passenger flight operated on 12 February 1963 by a Boeing 720 aircraft which broke up in midair and crashed into The Everglades shortly after take-off from Miami International Airport in a severe thunderstorm...
- A Northwest AirlinesNorthwest AirlinesNorthwest Airlines, Inc. was a major United States airline founded in 1926 and absorbed into Delta Air Lines by a merger approved on October 29, 2008, making Delta the largest airline in the world...
B-720BBoeing 720The Boeing 720 is a four-engine narrow-body short- to medium-range passenger jet airliner. Developed by Boeing in the late 1950s from the Boeing 707, the 720 has a shorter fuselage and less range...
was hit with a powerful updraft (it suddenly began climbing at 9,000 ft. per minute) while climbing through 17,000 ft as it tried to fly between thunderstorms shortly after takeoff. The nose pitched up so high that the pilot reacted by using full nose-down trim on the horizontal stabilizer (HS), while simultaneously pushing the elevators to the full down position. Then, an equally powerful down draft hit the plane and it went straight down in a matter of seconds. The pilot, of course pulled back on the yoke, which moved the elevators to the full up position. But, that imposed such a high G-load on the plane, that the HS jackscrew stalled, so that the HS remained in the full trimmed down position. The plane came apart in the air, before hitting the ground.
- July, 1963: A United AirlinesUnited AirlinesUnited Air Lines, Inc., is the world's largest airline with 86,852 employees United Air Lines, Inc., is the world's largest airline with 86,852 employees United Air Lines, Inc., is the world's largest airline with 86,852 employees (which includes the entire holding company United Continental...
B-720, while climbing through FL 370, upset and dove until recovery at 14,000 ft. The plane encountered severe turbulence, downdrafts and updrafts, which caused the plane to stall. The plane was approaching the coffin cornerCoffin corner (aviation)The coffin corner is the altitude at or near which a fast fixed-wing aircraft's stall speed is equal to the critical Mach number, at a given gross weight and G-force loading. At this altitude the airplane becomes nearly impossible to keep in stable flight...
of its flight envelopeFlight envelopeIn aerodynamics, the flight envelope or performance envelope of an aircraft refers to the capabilities of a design in terms of airspeed and load factor or altitude. The term is somewhat loosely applied, and can also refer to other measurements such as maneuverability...
, when the turbulence was encountered. After that near disaster, the stallStallIn fluid dynamics, a stall is a reduction in the lift coefficient generated by a foil as angle of attack increases. This occurs when the critical angle of attack of the foil is exceeded...
and mach buffet margins were widened on all jet aircraft, to preclude a plane getting into that situation again, where severe turbulence narrows the "coffin alley" margins so instantly that the pilots do not have time to avoid a high altitude stall.
- November, 1963: Trans-Canada Air Lines Flight 831Trans-Canada Air Lines Flight 831Trans-Canada Air Lines Flight 831 was a flight from Montreal-Dorval Airport to Toronto International Airport on November 29, 1963. The aircraft was a four-engine Douglas DC-8-54CF airliner, registered CF-TJN...
- All 118 on board a Trans-Canada Airlines DC-8-54F were killed, when the plane crashed 5 minutes after takeoff near Montreal, leaving a crater in the ground. Impact speed was over 500 mph. They found the pitch trim compensator actuator was in the extended position and the horizontal stabilizer trim setting was at 1.65 to 2 degrees nosedown (both were improper positions, for that stage of flight). "The probable cause of this accident could not be determined with certainty. Certain possible causes which were put forward could not be ruled out: 1) Icing of the PitotPitot-static systemA pitot-static system is a system of pressure-sensitive instruments that is most often used in aviation to determine an aircraft's airspeed, Mach number, altitude, and altitude trend. A pitot-static system generally consists of a pitot tube, a static port, and the pitot-static instruments...
system; 2) Failure of the vertical gyroGyro- Science and technology :* An abbreviation for gyroscope, an orientation-stabilizing device* An abbreviation for autogyro, a type of rotary-wing aircraft* The casually used brand name of a detangler mechanism, part of a stunt-adapted BMX bicycle...
; 3) An unprogrammed and unnoticed extension of the pitch trim compensator."
- February, 1964: Eastern Air Lines Flight 304Eastern Air Lines Flight 304Eastern Air Lines Flight 304 was a Douglas DC-8 flying from New Orleans International Airport to Washington Dulles International Airport that crashed on February 25, 1964. All 51 passengers and 7 crew were killed...
- An Eastern Airlines DC-8 crashed into Lake PontchartrainLake PontchartrainLake Pontchartrain is a brackish estuary located in southeastern Louisiana. It is the second-largest inland saltwater body of water in the United States, after the Great Salt Lake in Utah, and the largest lake in Louisiana. As an estuary, Pontchartrain is not a true lake.It covers an area of with...
about 5 minutes after taking off from the New Orleans Moisant Airport. All 58 on board perished. The water was only 20 ft. deep, yet only 60% of the wreckage was recovered, because the breakup was so extensive. The flight data recorderFlight data recorderA flight data recorder is an electronic device employed to record any instructions sent to any electronic systems on an aircraft. It is a device used to record specific aircraft performance parameters...
tape was too damaged to help the analysis. Instead, they used the maintenance records of that plane, and of other DC-8s, to conclude that the pilots had trimmed the stabilizer to the full nose-down position, to counter the excessive nose-up attitude that, in turn, was caused by a malfunctioning pitch trim compensator that had extended too far. Once the upset occurred, it was not possible to trim the HS back to the nose-up position, because of the severe G-forces generated by their pulling back on the yoke after the upset.
- February, 1985: China Airlines Flight 006China Airlines Flight 006China Airlines Flight 006 was a daily non-stop flight departing from Taipei at 16:15 and scheduled to arrive at Los Angeles International Airport at 07:00 local time. On February 19, 1985, it was involved in an aircraft upset accident after the No. 4 engine flamed out...
: The number 4 engine flamed out on a China AirlinesChina AirlinesChina Airlines is both the flag carrier and the largest airline of Republic of China . Although not directly state-owned, the airline is owned by China Airlines Group, which is owned by the China Aviation Development Foundation...
747SP, while cruising at FL 410 over the Pacific Ocean. The captain ordered an attempt to restart the engine, while remaining at flight level 410Flight levelA Flight Level is a standard nominal altitude of an aircraft, in hundreds of feet. This altitude is calculated from the International standard pressure datum of 1013.25 hPa , the average sea-level pressure, and therefore is not necessarily the same as the aircraft's true altitude either...
and with the autopilotAutopilotAn autopilot is a mechanical, electrical, or hydraulic system used to guide a vehicle without assistance from a human being. An autopilot can refer specifically to aircraft, self-steering gear for boats, or auto guidance of space craft and missiles...
controlling the plane. The airspeed was declining (because the remaining 3 engines did not have enough power to remain at a safe airspeed at that altitude). When the captain finally disconnected the AP, he failed to use left rudder to counteract the asymmetrical thrust, and the plane rolled rapidly to the right and entered a high dive attitude. He was unable to recover from the dive until below 11,000 ft. when they emerged from the clouds. The plane exceeded the maximum operating airspeed (Vmo) twice, during the dive. After recovery, the plane landed safely at San Francisco. It suffered major structural damage and 2 occupants received serious injuries.
Related accidents
- 1974-03-03 Turkish Airlines Flight 981Turkish Airlines Flight 981Turkish Airlines Flight 981 was a McDonnell Douglas DC-10, registered TC-JAV and named the Ankara, that crashed in Fontaine-Chaalis, Oise, France, outside Senlis, on 3 March 1974...
(cargo door failure, caused severing of essential flight control cables). - 1979-04-04 TWA Flight 841 (1979)TWA Flight 841 (1979)On April 4, 1979, a Boeing 727-31 operating as TWA Flight 841 took off from John F. Kennedy International Airport, New York City, en route to Minneapolis-Saint Paul International Airport in Minneapolis, Minnesota. Over Saginaw, Michigan, while the plane was cruising at 39,000 feet and Mach 0.816,...
(Improper manipulation of flaps/slats by pilots; the plane high dived from 39,000 ft. to 5,000 ft, in 63 seconds. Landed safely.) - 1985-08-12 Japan Airlines Flight 123Japan Airlines Flight 123Japan Airlines Flight 123 was a Japan Airlines domestic flight from Tokyo International Airport to Osaka International Airport on August 12, 1985. The Boeing 747-146SR that made this route, registered , suffered mechanical failures 12 minutes into the flight and 32 minutes later crashed into two...
(Improper repair caused bulkhead explosion, which severed all hydraulic flight control lines) - 1989-07-19 United Airlines Flight 232United Airlines Flight 232United Airlines Flight 232 was a scheduled flight from Stapleton International Airport in Denver, Colorado, to O'Hare International Airport in Chicago, with continuing service to Philadelphia International Airport...
(Catastrophic engine failure caused loss of all 3 hydraulic flight control lines) - 1994-06-30 1994 A330 test flight crash1994 A330 test flight crashThe 1994 A330 test flight crash occurred on when an Airbus A330-300, registration F-WWKH, crashed at Toulouse-Blagnac Airport while undergoing performance tests. It was the first fatal accident involving an Airbus A330 as well as the first hull-loss of the type...
(Control was lost after the pilot shut down one engine, close to the ground, during a certification test flight) - 1994-09-08 USAir Flight 427USAir Flight 427US Air Flight 427 was a scheduled flight from Chicago's O'Hare International Airport to Pittsburgh, with a final destination of West Palm Beach, Florida...
(Control lost when the rudder PCU malfunctioned, causing the rudder to move in the opposite direction, commanded by the pilot) - 1994-10-31 American Eagle Flight 4184American Eagle Flight 4184American Eagle Flight 4184 was an American Eagle ATR 72 that crashed after flying into unknown icing conditions on October 31, 1994. Control was lost and all aboard were killed.-History:...
While in a holding pattern, extensive ice accumulation produced a sudden reversal of the aileron controls, causing the plane to upset and dive into the ground. - 1994-12-11 Philippine Airlines Flight 434Philippine Airlines Flight 434Philippine Airlines Flight 434 was the route designator of a flight from Ninoy Aquino International Airport, Pasay City, the Philippines, to New Tokyo International Airport , Narita near Tokyo, Japan, with one stop at Mactan-Cebu International Airport, Cebu, the Philippines.On December 11, 1994...
- 2001-11-12 American Airlines Flight 587American Airlines Flight 587American Airlines Flight 587, an Airbus A300, crashed into the Belle Harbor neighborhood of Queens, a borough of New York City, New York, shortly after takeoff from John F. Kennedy International Airport on November 12, 2001. This is the second deadliest U.S...
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- 2005-03-06 Air Transat Flight 961Air Transat Flight 961Air Transat Flight 961 was a flight from Varadero, Cuba to Quebec City, Canada on March 6, 2005. The aircraft experienced a structural failure in which the rudder detached in flight...
- 2007-01-01 Adam Air Flight 574Adam Air Flight 574Adam Air Flight 574 was a scheduled domestic passenger flight operated by Adam Air between the Indonesian cities of Surabaya and Manado that disappeared near Polewali in Sulawesi on 1 January 2007. The plane, a Boeing 737-4Q8, was ultimately determined to have crashed into the ocean, from...
- 2009-02-12 Colgan Air Flight 3407Colgan Air Flight 3407Colgan Air Flight 3407, marketed as Continental Connection under a codeshare agreement with Continental Airlines, was a daily U.S. regional airline commuter flight from Newark Liberty International Airport in New Jersey to Buffalo Niagara International Airport in New York State.A Bombardier...
See also
- Boeing 737 rudder issuesBoeing 737 rudder issuesStarting in 1991, a number of accidents and incidents involving the Boeing 737 were the result of the airplanes' unexpected movement of their rudders. The rudder is controlled by the Power Control Unit . Inside the PCU is a dual servo valve which helps direct hydraulic fluid in order to move the...
- Inertia couplingInertia couplingInertia coupling is a potentially lethal phenomenon of high-speed flight in which the inertia of the heavier fuselage overpowers the aerodynamic stabilizing forces of the wing and empennage...
- List of aircraft upset factors
Further reading
- Dismukes, Key, Benjamin A. Berman and Loukia D. Loukopoulos. The Limits of Expertise. Aldershot: Ashgate, 2007. ISBN 978-0-7546-4965-6