The deadliest civilian helicopter crash on record happened 32 years ago today, in the sea just off the Shetland Islands.
Forty-three oil workers and two crew members died when the Boeing Chinook helicopter plunged 150 feet into the sea and broke up. Just two people survived the crash, both of them injured.
The Chinook, a large double rotor helicopter, was bringing workers from the Brent Oilfield back to Sumburgh Airport, the main airport serving the Shetland Islands. It was nearing the end of the 130-mile flight when disaster struck.
As it approached Sumburgh, the helicopter was cleared to land on runway 24, but suddenly the radio link went dead. Just 2.5 miles from the airport, the Chinook suffered a catastrophic failure in its forward transmission system – the gears operating the front of its tandem rotors. This failure de-synchronised the turning of the front rotor blades with those of the rear rotor, causing the front and rear blades to smash into each other.
The cockpit voice recorder (later recovered from the wreckage) revealed that the crew noticed an increased noise level on the flightdeck followed by a loud bang. The fought for control, hoping to ditch in the sea, but instead the helicopter pitched forward and nose-dived. Despite its size, the Chinook was designed to float following a controlled landing on water, giving the crew and passengers a chance to escape using onboard life rafts and inflatables.
Everyone on board was also wearing survival suits and had undergone training for a landing at sea, but nothing could have prepared them for the 150-foot plunge and the helicopter breaking up on impact and sinking. By chance, a Coastguard search and rescue helicopter had just departed Sumburgh Airport and immediately diverted to the scene of the crash. Its crew spotted two survivors clinging to wreckage and managed to winch them on board, but no more could be found.
The helicopter sank in 300 feet of water and an operation to salvage the wreckage began the next morning and lasted several days. As well as all the key components of the helicopter, all but one of the victims’ bodies were recovered. An official investigation into the crash led to changes in the procedures for testing key components before installation on helicopters, and then monitoring them more closely once in service.
In the aftermath of the accident, the oil industry decided that the Chinook was too big for shuttling workers to and from offshore installations. Remaining aircraft were withdrawn from service and sold, replaced with smaller helicopters. A £1.2 million three-year research project was also announced to study the best types of passenger helicopters and the protocols for operating them. It was jointly funded by the government, the aircraft industry and the Civil Aviation Authority.
Despite the crash, the Chinook had enjoyed a relatively good accident record since its introduction in 1962. Military versions remain in use around the world in heavy-lift non-passenger roles. Civilian versions also have various heavy-lift uses, including the logging and construction industries and aerial firefighting duties.
The 1986 disaster is commemorated by a memorial site at Sumburgh Airport, dedicated to all those who lost their lives in five aircraft accidents related to the offshore air industry. In total, 83 lives are honoured by the memorial, which opened in May 2013.