This is a list of accidents and incidents involving the Westland Sea King helicopter, a British license-built and developed version of the American Sikorsky Sea King anti-submarine and utility helicopter, , Westland Sea Kings have been involved in forty-six significant accidents and incidents, involving forty-eight aircraft, during their service career. This total includes thirty accidents and incidents involving Royal Navy helicopters, one involving a helicopter operated by the Empire Test Pilot's School, two involving helicopters owned by the German Navy, three involving helicopters operated by the Royal Norwegian Air Force, four were Sea Kings owned by the Indian Navy, one owned by the Pakistan Navy, and five involving Sea Kings operated by the Royal Australian Navy. Sixty-nine pilots and crewmembers have been killed in accidents involving Westland Sea Kings.
Of the accidents and incidents included in this list, six were caused by engine failure, while six flight-into-terrain accidents were recorded, with two additional hard landings resulting in serious damage to the aircraft. Seven more of the accidents and incidents were a result of problems in the helicopters' drive systems, while five others were caused by collisions, three of them being mid-air collisions - two with other Sea Kings, the third, with a Lockheed Hercules transport -, one a collision with the superstructure of a ship, and another a collision with a high-tension cable. Two accidents were the result of failure of the main rotor, with two others being caused by weather, while one accident each was caused by instrument failure, bird strike (presumed), fuel exhaustion, and on-board fire; eleven other accidents and incidents did not mention a specific cause, simply that the helicopter involved crashed or ditched without further detail being provided.
1970s
1972
13 January 1972 - Royal Navy Sea King HAS1 serial number XV645 of 737 Naval Air Squadron ditched and sank 22 miles south of Portland Bill following No. 2 engine runaway during the hover, crew rescued including one injured. 10 April 1972 - Royal Navy Sea King HAS1 XV662 of 826 Naval Air Squadron made a water landing off 6.9 miles of The Lizard due to extreme vibrations while hovering, rolled over and sank, crew rescued and helicopter recovered.
1974
16 January 1974 - Sea King Mk 41 89+61, undergoing factory tests before delivery to the German Navy, suffered wind shear during a circuit of the airfield at Yeovil; the pilot overcorrected attempting to recover, and the aircraft crashed into a building. All five crewmembers survived. 21 March 1974 - Royal Navy Sea King HAS1 XV702 of 824 Naval Air Squadron crashed into cliff during a night exercise at Downas Valley near Coverack, four crew killed. 19 November 1974 - Royal Navy Sea King HAS2 XV644 of 737 Naval Air Squadron ditched and sank 21 miles south of Portland Bill after tail rotor drive failure, crew picked up and helicopter salvaged. 12 December 1974 - Royal Navy Sea King HAS1 XV667 of 826 Naval Air Squadron made a night water landing in the Bay of Biscay while operating from HMS Tiger following loss of 5 ft from main rotor, crew vacated aircraft which then rolled over and sank, crew rescued.
1975
21 October 1975 - Royal Australian Navy Sea King Mk 50 N16-117 of 817 Squadron ditched in the sea near Shoalhaven Bight; the crew was recovered safely, and the helicopter was salvaged the following month, with its wreckage currently displayed at the Australian Fleet Arm Museum. 17 November 1975 - Royal Navy Sea King HAS1 XV695 of 819 Naval Air Squadron was operating in the North Sea from HMS Hermes when it ditched, rolled inverted and sank following engine problems, crew rescued.
1976
31 March 1976 - Royal Navy Sea King HAS1 XV669 of 820 Naval Air Squadron was operating from HMS Blake when it ditched, rolled over and sank when control was lost due to severe vibration, helicopter had lost the main rotor balance weights whilst dunking, crew rescued. 30 November 1976 - Royal Australian Navy Sea King Mk 50 N16-113 ditched in the sea off Kiama following the failure of the aircraft's transmission. Helo remained afloat for 6 hours then sank during salvage attempt; crew rescued uninjured..
1977
30 April 1977 - Royal Norwegian Air Force Sea King Mk. 43 072 of 330 Squadron suffered a tail rotor strike during hovering over the sea and crashed; all four crewmembers died. 25 October 1977 - Royal Navy Sea King HAS1 XV646 of 814 Naval Air Squadron ditched and sank in south western approaches following tail rotor transmission failure, crew rescued, helicopter not recovered.