G-ASWI was a Westland Wessex 60, operated by Bristow Helicopters operating between Bacton Gas Terminal, in Norfolk, and gas rigs in the North Sea. On 13 August 1981 the helicopter lost power to the main rotor gearbox, going out of control during the ensuing autorotation. The flight was carrying 11 gas workers from the Leman gas field to Bacton. All people on board were lost.

• http://en.wikipedia.org/wiki/G-ASWI North Sea ditching