Scandinavian Airlines System Flight 901

Investigation

The National Transportation Safety Board (NTSB) investigated the accident. Investigators first thought a probable cause of the overshoot could be hydroplaning since there was bad weather on arrival, but this was later ruled out when investigators inspected the runway and found that the grooves on the runway were in good condition and there were no recent reports of hydroplaning on that runway. The NTSB discovered from eyewitnesses that the airport's control tower could not see the flight arriving due to low visibility. However, they and passengers on the flight reported that the aircraft traveled an unusually long distance before landing. According to the flight's cockpit voice and flight data recorders, the aircraft was at an unusually high speed of 205 knots before landing. It was also noticed that the captain only monitored his airspeed, not the shown ground speed. To avoid striking the approach lighting system, they veered the DC-10 off Runway 04R using the aircraft's rudder. The aircraft came to a rest in shallow water 650 ft from Runway 04R.

Investigators discovered that the captain was relying on the aircraft's autothrottle, believing that it would automatically decrease turbine power. NTSB investigators also found that the autothrottle control system had malfunctioned during previous flights. They believe that during the approach, the DC-10's autothrottle had a software malfunction, leading to increased airspeed before touching down. In the NTSB's final report, the probable cause of SAS Flight 901 states that "The flightcrew's disregard for prescribed procedures for monitoring and controlling of airspeed during the final stages of the approach and (b) decision to continue the landing rather than to execute a missed approach, and (c) overreliance on the autothrottle speed control system which had a history of recent malfunctions".