Article on "Scandinavian Airlines System Flight 751 Crash"

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 (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 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 Scandinavian Airlines System (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.

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, 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 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, but, with the aircraft emerging from cloud cover at 890 ft (270 m) altitude, they chose a field in the forest, near the V?ngsj?berg seat farm in Gottr?ra, 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.]Scandinavian Airlines System 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 Gottr?ra, 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 disabling both engines. All 129 passengers and crew aboard survived.