Scandinavian Airlines Flight 751

Last updated

Scandinavian Airlines Flight 751
SAS McDonnell Douglas MD-81 (DC-9-81) OY-KHO KvW-1.jpg
OY-KHO, the aircraft involved in the crash.
Accident
Date27 December 1991
SummaryDual engine failure due to foreign object damage [1]
Site Gottröra, Norrtälje Municipality, Sweden
59°46′06″N018°07′55″E / 59.76833°N 18.13194°E / 59.76833; 18.13194 Coordinates: 59°46′06″N018°07′55″E / 59.76833°N 18.13194°E / 59.76833; 18.13194
Aircraft
Aircraft type McDonnell Douglas MD-81
Aircraft nameDana Viking
Operator Scandinavian Airlines System
Registration OY-KHO
Flight origin Stockholm Arlanda Airport
Stopover Copenhagen Airport
Destination Warsaw Chopin Airport
Occupants129
Passengers123
Crew6
Fatalities0
Injuries92 (8 serious, 84 minor)
Survivors129

Scandinavian Airlines Flight 751 was a regularly scheduled Scandinavian Airlines passenger flight from Stockholm, Sweden, to Warsaw, Poland, via Copenhagen, Denmark. On 27 December 1991, a McDonnell Douglas MD-81 operating the flight, registration OY-KHO, piloted by Danish Captain Stefan G. Rasmussen (44) and Swedish first officer Ulf Cedermark (34), both experienced pilots with 8,000 and 3,000 flight hours, respectively, was forced to make an emergency landing in a field near Gottröra, Sweden. Ice had collected on the wings' inner roots (close to the fuselage) before takeoff, broke off, and was ingested into the engines as the aircraft became airborne on takeoff, ultimately resulting in the failure of both engines. All 129 passengers and crew aboard survived.

Contents

The incident is known as the Gottröra crash (Swedish : Gottrörakraschen) or the Miracle at Gottröra (Swedish : Miraklet i Gottröra) in Sweden. [2] [3]

Aircraft

The aircraft was a McDonnell Douglas MD-81, registered OY-KHO with serial number 53003, line number 1844. It made its first flight on 16 March 1991, and was delivered soon after to SAS on 10 April 1991. At the time of the accident, the aircraft had been in service for only nine months. It was fitted with two Pratt & Whitney JT8D low-bypass turbofan engines. [4]

Accident

The aircraft had arrived at Stockholm-Arlanda Airport at 22:09 local time after a flight from Zürich the previous evening and was parked overnight at temperatures of around 0 to 1 °C (32 to 34 °F). About 2,550 kilograms (5,620 lb) of very cold, flight-chilled fuel remained in the wing tanks. Due to this, clear ice had formed on the upper side of the wings, but was not detected. The aircraft was de-iced with 850 litres (190 imp gal; 220 US gal) of de-icing fluid, but not checked afterwards for remaining ice by the de-icing personnel or the Pilot-in-Charge, Captain Rasmussen, which he was required to do by the Scandinavian Airlines "Flight Deck Bulletin/Winterization" given to pilots. [5]

The plane departed from Stockholm at 08:47. Shortly after liftoff, pieces of ice broke off and slammed into the fans of both engines, deforming the fan blades sufficiently to disturb the airflow to the compressors. The disturbed airflow caused the compressors to stall and this in turn caused the engines to surge. As the engines were not throttled down sufficiently, the surges continued. The high loads from repeated engine surges quickly led to the breakup of both engines.

From the pilots' point of view, after 25 seconds of flight, noises and vibrations caused by the No. 2 engine surging were first noticed. The flight crew responded by throttling down a little, but an automatic system, ATR (automatic thrust restoration), that had not been described to the flight crew by SAS, simultaneously increased throttle as a response to the asymmetric engine power and reduced climb rate. As a consequence, the engine surges continued. SAS Flight Captain Per Holmberg, who was on board as a passenger, noticed the problems early and hurried to the cockpit to assist the crew. Engine No. 1 surged 39 seconds later and both engines failed at 76 and 78 seconds, respectively, into flight, at an altitude of 3,220 ft (980 m).

The pilot responded to the loss of both engines by pitching the aircraft down in a dive before leveling it, to try to have it glide the longest possible distance without stalling. The pilots requested a return to Arlanda and attempted the restart procedure, [6] but, with the aircraft emerging from cloud cover at 890 ft (270 m) altitude, they chose a field in the forest, near the Vängsjöberg seat farm in Gottröra, Uppland, for an immediate emergency landing.

During the final descent, the aircraft hit several trees, losing a large part of the right wing. It struck the ground tail-first, and the tail cone of the plane broke off. The plane slid across the field for 110 metres (360 ft), during which the main landing gear of the plane dug marks into the field and sheared off, the nose landing gear broke off, and the fuselage broke into three parts. As a result of the accident, 25 people were injured—two of them seriously—but there were no fatalities. The flight attendants had instructed passengers to adopt the brace position, which is credited with the lack of fatalities. [7]

The flight crew, and especially Captain Rasmussen, were lauded for the skilled emergency landing in a fast-developing, potentially fatal situation. Rasmussen commented that "few civilian air pilots are ever put to a test of the skills they have acquired during training to this degree".[ citation needed ] He said he was proud of his crew and very relieved everyone had survived. He chose not to return to piloting commercial aircraft.

Scandinavian Airlines continues to use flight number 751 for its Copenhagen-to-Warsaw route. [8]

Investigation and recommendations

According to the official accident report by the Swedish Accident Investigation Board (SHK), the problem of clear ice formation on the wings in this type of aircraft was a well-known phenomenon at the time of the accident. From 1985 onward, McDonnell Douglas gave extensive information, including several "All Operators Letters" that dealt with the clear ice problem. In the "All Operators Letter" of 14 October 1986, operators were informed of how the Finnish airline Finnair had solved the problem of discovering clear ice. In 1988 and 1989, McDonnell Douglas arranged "Theme Conferences" dealing with clear ice formation. SAS took part in these conferences. [5] :61

On 26 October 1991, SAS distributed a "Flight Deck Bulletin/Winterization" to all pilots. It stated: "It is the Pilot-in-Charge's responsibility to check the aircraft for any ice or snow that may affect performance" and in the section "Clear Ice", it noted " [a]lthough the awareness within Line Maintenance is mostly good, the responsibility again rests with the Pilot-in-Charge that the aircraft is physically checked by means of a hands-on check on the upper side of the wing. A visual check from a ladder or when standing on the ground is not enough". [5]

Another contribution to the accident was insufficient training of the crew; they were not trained in restoring engine operation after they repeatedly surged. There was no simulator or other training on the engine surging problem. Secondly, they were not informed about a pre-installed automatic thrust system (automatic thrust restoration or ATR). The reason for this lapse of information was that there was no knowledge of ATR within SAS. However, ATR was described in manuals by the aircraft manufacturer which every operator is obliged to know. Even though the system was developed for use in procedures not applied by SAS, a sufficiently careful study of the manuals should have led to SAS noting the system and training its pilots in its function. [5]

The conclusion of the official accident report stated:

Contributary causes were:

In the section "Compressor Failures", the report stated:

However, the newly installed ATR prevented the pilots from successfully performing the normal remedial measure to halt compressor stall, i.e., throttling back the engines, as the ATR system – designed to prevent pilots from using less than normal thrust when climbing out after take-off for noise abatement reasons – restored engine take-off power throttle settings, contrary to the pilots' reduced throttle commands. This damaged the engines, until eventually, they failed completely removing any possibility of a crash-avoiding restart. The ATR system designed for safety forced the plane into a crash landing with no other options. This use of a safety system meant to operate in spite of and independent from any cockpit controls would rear its ugly head again in 2018 when an MCAS (Maneuvering Characteritics Augmentation System) system was installed in Boeing's new 737 Max. Similar in design, it was meant to prevent the plane from ever stalling and would act against the actions of the pilot so that even when the computer mistakenly thought it was stalling would force the plane to the ground rendering the pilots powerless against it. This hidden "safety system" was responsible for two major crashes and 346 deaths. [9]

The story of the accident was featured on the tenth season of the Canadian TV series Mayday. The episode is entitled "Pilot Betrayed." [10]

See also

Related Research Articles

Linate Airport disaster Aircraft accident in Milan, Italy in 2001

The Linate Airport disaster occurred in Italy in 2001 at Linate Airport in Milan on the morning of Monday, 8 October. Scandinavian Airlines Flight 686, a McDonnell Douglas MD-87 airliner carrying 110 people bound for Copenhagen, Denmark, collided on take-off with a Cessna Citation CJ2 business jet carrying four people bound for Paris, France. All 114 people on both aircraft were killed, as well as four people on the ground.

McDonnell Douglas MD-80 Jet airliner, next generation series based on the DC-9

The McDonnell Douglas MD-80 is a series of single-aisle airliners developed by McDonnell Douglas from the earlier DC-9. Stretched, heavier, and with higher bypass Pratt & Whitney JT8D-200 engines, the DC-9 Series 80 was launched in October 1977. It made its first flight on October 18, 1979 and was certified on August 25, 1980. It was first delivered to launch customer Swissair on September 13, 1980, which introduced it into commercial service on October 10, 1980.

Delta Air Lines Flight 1141 1988 aviation accident

Delta Air Lines Flight 1141 was a scheduled domestic passenger flight between Dallas/Fort Worth, Texas and Salt Lake City, Utah. On August 31, 1988, the flight, using a Boeing 727-200 series aircraft, crashed during takeoff, resulting in 14 deaths and 76 injuries of the 108 people on board.

Pratt & Whitney JT8D

The Pratt & Whitney JT8D is a low-bypass turbofan engine introduced by Pratt & Whitney in February 1963 with the inaugural flight of the Boeing 727. It was a modification of the Pratt & Whitney J52 turbojet engine which powered the US Navy A-6 Intruder attack aircraft. Eight models comprise the JT8D standard engine family, covering the thrust range from 12,250 to 17,400 pounds-force and power 727, 737-100/200, and DC-9 aircraft. The Volvo RM8 is an afterburning version that was license-built in Sweden for the Saab 37 Viggen fighter. Pratt & Whitney also sells static versions for powerplant and ship propulsion as the FT8.

A compressor stall is a local disruption of the airflow in the compressor of a gas turbine or turbocharger. A stall that results in the complete disruption of the airflow through the compressor is referred to as a compressor surge. The severity of the phenomenon ranges from a momentary power drop barely registered by the engine instruments to a complete loss of compression in case of a surge, requiring adjustments in the fuel flow to recover normal operation.

McDonnell Douglas DC-9 Twin-engine, single-aisle jet airliner produced 1965-1982

The McDonnell Douglas DC-9 is a single-aisle airliner designed by the Douglas Aircraft Company. After introducing its heavy DC-8 in 1959, Douglas approved the smaller, all-new DC-9 for shorter flights on April 8, 1963. The DC-9-10 first flew on February 25, 1965 and gained its type certificate on November 23, to enter service with Delta Air Lines on December 8. With five seats across in economy, it had two rear-mounted Pratt & Whitney JT8D turbofans under a T-tail for a cleaner wing, a two-person flight deck and built-in airstairs.

A takeoff/go-around switch is a switch on the autothrottle of modern large aircraft, with two modes: takeoff (TO) and go-around (GA). The mode is dependent on the phase of flight; usually, on approach to land, the autopilot will be set to approach mode, therefore if the TO/GA switch is pressed it will activate the go-around mode of the autothrottle; conversely, when take-off is set on the autopilot, the switch activates take off mode of the autothrottle. On Boeing aircraft TO/GA modes are selected by a separate switch near the throttle levers, but on Airbus aircraft it is activated by pushing the thrust levers fully forward to the TO/GA detent.

TWA Flight 159 1967 aviation accident

Trans World Airlines (TWA) Flight 159 was a regularly scheduled passenger flight from New York City to Los Angeles, California, with a stopover in Cincinnati/Northern Kentucky International Airport, Kentucky, that crashed after an aborted takeoff from Cincinnati on 6 November 1967. The Boeing 707 attempted to abort takeoff when the copilot became concerned that the aircraft had collided with a disabled DC-9 on the runway. The aircraft overran the runway, struck an embankment and caught fire. One passenger died as a result of the accident.

Stefan G. Rasmussen is a former Danish pilot who captained the crash-landing SAS flight 751 on 27 December 1991. There were no fatalities in the crash, and Rasmussen received much recognition for his handling of the incident. He entered politics, and served in the Danish Folketing parliament from 1994 to 1996.

Spanair Flight 5022 August 2008 plane crash in Madrid, Spain

Spanair Flight 5022 (JK5022) was a scheduled domestic passenger flight from Barcelona–El Prat Airport to Gran Canaria Airport, Spain, via Madrid–Barajas Airport that crashed just after take-off from runway 36L at Madrid Airport at 14:24 CEST (12:24 UTC) on 20 August 2008. The aircraft was a McDonnell Douglas MD-82, registration EC-HFP. Of the 172 passengers and crew on board, 154 died and 18 survived.

Japan Airlines Flight 446 1972 aviation accident

Japan Airlines Flight 446 was a Japan Airlines flight from Sheremetyevo International Airport of Moscow, Russian SFSR, Soviet Union to Tokyo International Airport in Ōta, Tokyo, Japan.

Several aviation incidents and accidents have occurred in which the control surfaces of the aircraft became disabled, often due to failure of hydraulic systems or the flight control system. Other incidents have occurred where controls were not functioning correctly prior to take-off, either due to maintenance or pilot error, and controls can become inoperative from extreme weather conditions. Aircraft are not designed to be flown in such circumstances, however a small number of pilots have had some success in flying and landing aircraft with disabled controls.

1955 MacArthur Airport United Airlines crash Airplane crash in New York

On April 4, 1955, a United Airlines Douglas DC-6 named Mainliner Idaho crashed shortly after taking off from Long Island MacArthur Airport, in Ronkonkoma, Islip, New York, United States.

United Airlines Flight 2885 1983 aviation accident

United Airlines Flight 2885 was a scheduled cargo flight from Cleveland to Los Angeles, with stopover in Detroit. On January 11, 1983, a DC-8 operating Flight 2885 crashed after take-off from Detroit, killing all 3 crew. The National Transportation Safety Board (NTSB) investigation determined that the cause for the crash was pilot error.

Air Algérie Flight 5017 July 2014 plane crash in Mali

Air Algérie Flight 5017 was a scheduled international passenger flight from Ouagadougou, Burkina Faso, to Algiers, Algeria, which crashed near Gossi, Mali, on 24 July 2014. The McDonnell Douglas MD-83 twinjet with 110 passengers and 6 crew on board, operated by Swiftair for Air Algérie, disappeared from radar about fifty minutes after take-off. There were no survivors.

Delta Air Lines Flight 1288 1996 aviation accident

Delta Air Lines Flight 1288 was a regularly scheduled flight from Pensacola, Florida, to Atlanta, Georgia. On July 6, 1996, the aircraft serving the flight, a McDonnell Douglas MD-88, was on takeoff roll from Runway 17 at Pensacola when it experienced an uncontained, catastrophic turbine engine failure that caused debris from the front compressor hub of the number one left engine to penetrate the left aft fuselage. The impact left two passengers dead and two severely injured; the two dead were a mother and son. The pilot aborted takeoff and the airplane stopped on the runway. Three other passengers sustained minor injuries during the emergency evacuation. Most of the passengers were traveling on vacation.

Scandinavian Airlines System Flight 901 1984 aviation accident

Scandinavian Airlines System Flight 901, also known as SAS Flight 901, was a scheduled international flight operated by the Scandinavian Airlines System, that overran the runway at its destination at John F. Kennedy International Airport on February 28, 1984. The flight, operated by a McDonnell Douglas DC-10, originated at Stockholm Arlanda Airport, Sweden, before a stopover at Oslo Airport, Gardermoen, Norway. All 177 passengers and crew members on board survived, although 12 were injured. The cause was a runway overshoot due to the crew's failure to monitor their airspeed and overreliance on the aircraft's autothrottle.

Pan Am Flight 799 1968 airplane crash

Pan Am Flight 799 was an international cargo flight from Los Angeles International Airport to Cam Ranh Airport in South Vietnam that crashed on December 26, 1968 near Anchorage, Alaska. The aircraft involved was a Boeing 707-321C aircraft operated by Pan American World Airways. All three crew members died in the crash.

Ryan International Airlines Flight 590 1991 aviation accident

Ryan International Airlines Flight 590 was a cargo flight carrying mail for the United States Postal Service from Greater Buffalo International Airport (BUF) in Buffalo, New York, to Indianapolis International Airport (IND) in Indiana, with a stopover at Cleveland Hopkins International Airport (CLE) in Cleveland, Ohio. On February 17, 1991, the McDonnell Douglas DC-9-15RC operating the flight crashed on takeoff from Cleveland during icing conditions. Both pilots, the aircraft's only occupants, were killed. The National Transportation Safety Board (NTSB) determined that the causes of the crash were the flight crew failing to de-ice their aircraft, as well as the inexperience of the Federal Aviation Administration (FAA), McDonnell Douglas, and Ryan International Airlines with icing condition on DC-9-10 aircraft.

References

  1. ↑ http://lessonslearned.faa.gov/ll_main.cfm?TabID=3&LLID=29&LLTypeID=2
  2. ↑ "Gottrörakraschen" [The Gottröra Crash]. P3 Dokumentär (in Swedish). 4 May 2008. Sveriges Radio. P3. Retrieved 25 August 2020.
  3. ↑ "Miraklet i Gottröra rör upp känslorna efter 20 år igen" [The miracle in Gottröra stirs up the emotions again after 20 years]. Expressen (in Swedish). Retrieved 15 February 2017.
  4. ↑ "McDonnell Douglas MD-80/90 MSN 53003". Airfleets.net. Retrieved 3 September 2015.
  5. 1 2 3 4 "Air Traffic Accident on 27 December 1991 at Gottröra, AB county" (PDF) (Official accident report). Report C 1993:57. Case L-124/91. Swedish Accident Investigation Authority. 20 October 1993. Retrieved 3 September 2015.
  6. ↑ Cockpit Voice Recorder transcript for SK 751 Hosted at aviation-safety.net
  7. ↑ Damski, Anna. "Brace Position". Inflight Safety Page. Retrieved 21 January 2011.
  8. ↑ "Flight Radar 24".
  9. ↑ https://transportation.house.gov/imo/media/doc/2020.09.15%20FINAL%20737%20MAX%20Report%20for%20Public%20Release.pdf
  10. ↑ "Air Emergency" Pilot Betrayed (TV Episode 2011) , retrieved 15 February 2017
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.