On 16 July 1983, British Airways Helicopters' commercial Sikorsky S-61 helicopter Oscar November (G-BEON) 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.