The Westland Wessex is a British turbine-powered version of the Sikorsky S-58 "Choctaw", developed under license by Westland Aircraft (later Westland Helicopters), initially for the Royal Navy, and later for the Royal Air Force (RAF). The Wessex operated as an anti-submarine warfare and utility helicopter in multiple nations, it is perhaps most well known in Britain for its service as a search and rescue (SAR) helicopter. The type first entered service in 1961.