Scandinavian Airlines System Flight 751 was a regularly scheduled

Scandinavian Airlines The Scandinavian Airlines System (SAS), commonly known as Scandinavian Airlines, is the national airline of Denmark, Norway, and Sweden. It is part of SAS Group and is headquartered in Solna, Sweden. Including its subsidiaries SAS Link and ...

passenger flight from

Stockholm Stockholm (; ) is the Capital city, capital and List of urban areas in Sweden by population, most populous city of Sweden, as well as the List of urban areas in the Nordic countries, largest urban area in the Nordic countries. Approximately ...

Sweden Sweden, formally the Kingdom of Sweden, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. It borders Norway to the west and north, and Finland to the east. At , Sweden is the largest Nordic count ...

, to

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, via

Copenhagen Copenhagen ( ) is the capital and most populous city of Denmark, with a population of 1.4 million in the Urban area of Copenhagen, urban area. The city is situated on the islands of Zealand and Amager, separated from Malmö, Sweden, by the ...

Denmark Denmark is a Nordic countries, Nordic country in Northern Europe. It is the metropole and most populous constituent of the Kingdom of Denmark,, . also known as the Danish Realm, a constitutionally unitary state that includes the Autonomous a ...

. On 27 December 1991, a

McDonnell Douglas MD-81 The McDonnell Douglas MD-80 is a series of five-abreast single-aisle airliners developed by McDonnell Douglas. It was produced by the developer company until August 1997 and then by Boeing Commercial Airplanes. The MD-80 was the second gener ...

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 Gottröra is a village in Norrtälje Municipality in the county of Stockholm, Sweden. Several hundred ancient monument An ancient monument can refer to any early or historical manmade structure or architecture. Certain ancient monuments are o ...

, Sweden. Ice had collected on the wings' inner

roots A root is the part of a plant, generally underground, that anchors the plant body, and absorbs and stores water and nutrients. Root or roots may also refer to: Art, entertainment, and media * ''The Root'' (magazine), an online magazine focusin ...

(close to the fuselage) before takeoff, broke off, and was ingested into the engines as the aircraft became airborne on takeoff, ultimately disabling both engines. All 129 passengers and crew aboard survived. The incident is known as the Gottröra crash () or the Miracle at Gottröra () in Sweden.

Aircraft

The aircraft involved was a

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53003,

registered Registered may refer to: * Registered mail, letters, packets or other postal documents considered valuable and in need of a chain of custody * Registered trademark symbol, symbol ® that provides notice that the preceding is a trademark or service ...

as OY-KHO, that was manufactured by

McDonnell Douglas McDonnell Douglas Corporation was a major American Aerospace manufacturer, aerospace manufacturing corporation and defense contractor, formed by the merger of McDonnell Aircraft and the Douglas Aircraft Company in 1967. Between then and its own ...

in 1991. It had logged approximately 1608 airframe hours and 1272 takeoff and landing cycles and was equipped with two Pratt & Whitney JT8D-217C engines.

Accident

The aircraft had arrived at

Stockholm Arlanda Airport Stockholm Arlanda Airport is the main international airport serving Stockholm, the capital of Sweden. It is located in Sigtuna Municipality, north of Stockholm and nearly southeast of Uppsala. The airport is located within Stockholm County. ...

at 22:09 local time after a flight from

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the previous evening and was parked overnight at temperatures of around . About 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 of de-icing fluid, but not checked afterwards for remaining ice by the de-icing personnel or the Pilot-in-Charge, Captain

Rasmussen The surname Rasmussen () is a Danish and Norwegian surname, meaning ''Rasmus' son''. It is the ninth-most-common surname in Denmark, shared by about 1.9% of the population. 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 Compressor stall, 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, hurried to the cockpit, and provided invaluable assistance to 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 . 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, but, with the aircraft emerging from cloud cover at altitude, they chose a field in the forest, near the Vängsjöberg

seat farm In Scandinavia, a seat farm or manor farm (; Norwegian language, Norwegian /; or ; ) was a farm where a nobility, nobleman had his permanent residence. They were found in the Kingdom of Denmark, the Kingdom of Norway, the Kingdom of Sweden, and ...

Uppland Uppland is a historical province or ' on the eastern coast of Sweden, just north of Stockholm, the capital. It borders Södermanland, Västmanland and Gästrikland. It is also bounded by lake Mälaren and the Baltic Sea. The name literally ...

, 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 , 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 To assume a brace position or crash position is an instruction that can be given to prepare for a crash, such as on an aircraft; the instruction to "Brace for impact!" or "Brace! Brace!" is often given if the aircraft must make an emergency land ...

, which is credited with the lack of fatalities. The flight crew, and especially Captain

Rasmussen The surname Rasmussen () is a Danish and Norwegian surname, meaning ''Rasmus' son''. It is the ninth-most-common surname in Denmark, shared by about 1.9% of the population.Post-traumatic stress disorder, PTSD from the aftermath of the accident when he was both called a hero and a villain despite him just believing he did the job he was trained for.

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 Finnair Plc (, ) is the flag carrier and largest full-service legacy airline of Finland, with headquarters in Vantaa on the grounds of Helsinki Airport, its airline hub, hub. Finnair and its subsidiaries dominate both domestic and international ...

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. 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 " though 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". Scandinavian 751 wreckage

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. Nonetheless, 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. The conclusion of the official accident report stated: In the section "Compressor Failures", the report stated: The newly installed ATR prevented the pilots from successfully performing the normal remedial measure to halt

compressor stall 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 o ...

, ''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 Noise control or noise mitigation is a set of strategies to reduce noise pollution or to reduce the impact of that noise, whether outdoors or indoors. Overview The main areas of noise mitigation or abatement are: transportation noise control, a ...

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.

In popular culture

The story of the accident was featured on the tenth season of the Canadian TV series ''

Mayday Mayday is an emergency procedure word used internationally as a distress signal in voice-procedure radio communications. It is used to signal a life-threatening emergency primarily by aviators and mariners, but in some countries local organiz ...

.'' The episode is titled "Pilot Betrayed".

References

External links

* Swedish Accident Investigation Board (SHK) *
Final report
– Translated from the original Swedish by Tim Crosfield M.A., at the request of the SHK.
Archive
*
Final report
– The original version.
Archive

Radio documentary from Swedish Radio P3 about the incident. (Swedish)

{{Aviation accidents and incidents in Sweden 1991 in Sweden 1991 meteorology Accidents and incidents involving the McDonnell Douglas MD-81 Airliner accidents and incidents caused by engine failure Airliner accidents and incidents caused by ice Aviation accidents and incidents in 1991 Aviation accidents and incidents in Sweden

751 Year 751 ( DCCLI) was a common year starting on Friday of the Julian calendar. The denomination 751 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming ...

December 1991 in Europe 20th century in Stockholm County