Sikorsky S-61N crash near Isles of Scilly, Cornwall, United Kingdom

British Airways Helicopters Flight 5918, a Sikorsky S-61N (G-BEON), crashed into the Celtic Sea 1.5 miles east of St Marys Aerodrome while on a scheduled passenger service from Penzance to the Isles of Scilly. Of 26 on board (23 passengers and 3 crew), 20 were killed and 6 survived. The AIB investigation found pilot error: the crew failed to notice and correct an unintentional descent while flying at low altitude in poor visibility. It was the worst UK civil helicopter accident at the time.