The Sumburgh disaster was the crash of a Boeing 234LR Chinook helicopter on 6 November 1986 with a loss of 43 passengers and two crew members. The helicopter was on approach to land at Sumburgh Airport Shetland Islands returning workers for the Brent oilfield. At 2.5 miles (4.0 km) from the runway the helicopter had a catastrophic forward transmission failure which de-synchronised the twin rotors causing the blades to collide.