What happened
A Lockheed Super Constellation was conducting a MATS military charter flight from Gander to Frankfurt when an emergency developed during the cruise phase. At approximately 20:09 GMT, while flying at FL210, a fire broke out in the number 3 engine. The crew responded by shutting down the engine and feathering the propeller.
Five minutes after this initial event, the flight engineer mistakenly closed the firewall shut-off valve for the number 1 engine, which caused that engine to overspeed. Following this error, the crew was unable to successfully restart the engine. The flight crew attempted to divert the aircraft toward Shannon using power from the remaining functional engines, specifically utilizing METO power on engine no. 4 and reduced power on engine no. 2.
During the diversion, the number 2 engine lost power and eventually failed completely. With two engines inoperative and a third compromised, the crew was forced to perform an emergency ditching at sea. Upon impact with the water, the left wing of the aircraft detached, though the main fuselage stayed intact. The cabin flooded rapidly, causing the aircraft to sink nose-first within approximately 10 minutes.
The Swiss merchant vessel 'Celerina' arrived at the scene first and assisted in rescue operations. The crew of the ship managed to evacuate 48 wounded individuals. However, the accident resulted in 28 fatalities, which included five members of the aircraft crew.
Findings
The incident was driven by the simultaneous failure of two engines and a critical error made by the flight engineer, whose improper handling of the number 1 engine's shut-off valve disabled a third power plant.