High Quality Content by WIKIPEDIA articles! On 16 July 1983, British Airways Helicopters' commercial Sikorsky S-61 helicopter Oscar November crashed in the southern Celtic Sea, in the Atlantic Ocean, when en route from Penzance to the St Mary's, Isles of Scilly in thick fog. Only six of the 26 on board survived. It sparked a review of helicopter safety and was the worst civilian helicopter disaster in the UK until 1986, when Boeing 234LR Chinook helicopter G-BWFC crashed in the North Sea. Owned by British Airways Helicopters, the Sikorsky S-61N registered G-BEON operated between Aberdeen and the oil platforms of the North Sea. On 22 June 1983, Oscar November received its last annual certificate of airworthiness. On 24 June 1983, it was being used as a replacement helicopter, operating the British Airways Helicopters service between Penzance and the Isles of Scilly. The helicopter which would normally run the service, ever since its purchase in 1974, was in for repairs.