Sumburgh disaster: A British International Helicopters Boeing 234LR Chinook crashes 21⁄2 miles east of Sumburgh Airport killing 45 people. It is the deadliest civilian helicopter crash on record.

On 6 November 1986, a Boeing-Vertol Model 234LR Chinook helicopter returning workers from the Brent oilfield crashed on approach to land at Sumburgh Airport in the Shetland Islands. At 2.5 mi (4.0 km) from the runway the helicopter had a catastrophic forward transmission failure which caused the tandem rotor blades to collide. The helicopter crashed into the sea and sank. Forty-three passengers and two crew members were killed in the crash; one passenger and one crew member survived with injuries.

British International Helicopter Services (BIH), owned by Bristow Group, is a British-owned helicopter operator. It operates a fleet of ten helicopters covering search and rescue, offshore, defence, charter and flying training activities from its bases at Newquay Airport, Coventry Airport and RAF Mount Pleasant in the Falkland Islands.

The Boeing CH-47 Chinook is a tandem-rotor helicopter originally developed by American rotorcraft company Vertol and now manufactured by Boeing Defense, Space & Security. The Chinook is a heavy-lift helicopter that is the second heaviest lifting Western helicopter to the Sikorsky CH-53. Its name, Chinook, is from the Native American Chinook people of Oregon and Washington state.

Sumburgh Airport is the main airport serving the island of Shetland, Scotland. It is located on the southern tip of the mainland, in the parish of Dunrossness, 17 NM south of Lerwick. The airport is owned by Highlands and Islands Airports Limited (HIAL) and served by Loganair.