British Airways Helicopters Flight 5918
On 16 July 1983, British Airways Helicopters Flight 5918, a British Airways Helicopters commercial Sikorsky S-61 helicopter, Oscar November (G-BEON), crashed in the southern Celtic Sea, in the Atlantic Ocean, while en route from Penzance to St Mary's, Isles of Scilly in poor visibility. Only six of the twenty-six people on board survived.
Source: Wikipedia — British Airways Helicopters Flight 5918 (CC BY-SA 4.0)