1986 British International Helicopters Chinook crash

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1986 British International Helicopters Chinook crash

What happened
On 6 November 1986, a Boeing-Vertol 234LR Chinook helicopter, operated by British International Helicopters and registered G-BWFC, crashed into the sea near Sumburgh Airport in the Shetland Islands. The aircraft was returning workers from the Brent oilfield to Sumburgh after making several platform stops. There were 47 people on board: 44 passengers and 3 crew. Forty-five people died and two survived.

Crew
- Captain Pushp Vaid (45) survived. He had been a former Indian Air Force pilot and joined British International Helicopters in 1975, flying the Chinook since 1982.
- First Officer Neville Nixon (43) did not survive.

What happened technically
The helicopter was descending to land at Sumburgh when a catastrophic failure occurred in the forward transmission. A modified bevel ring gear failed, causing the twin rotors to clash when their synchronization was lost. The rotor blades collided, the helicopter broke up in mid‑air, and crashed into the sea, sinking quickly.

Rescue and recovery
A Coast Guard Sikorsky rescue helicopter spotted a survivor on wreckage and later another survivor among the floating bodies. An air and sea search recovered most of the victims. The diving support vessel Deepwater 1 and the MSV Stadive assisted in locating and recovering wreckage and bodies. The cockpit voice recorder and major components were recovered and sent to the Air Accidents Investigation Branch for analysis. In total, 44 of the 45 victims’ bodies were recovered.

Cause and recommendations
The accident was traced to the failure of the forward transmission gear, which allowed the tandem rotors to collide. The AAIB cited deficiencies in the testing and inspection of modifications as underlying causes. The safety board issued three recommendations:
- Strengthen certification procedures so that all modifications to vital components are thoroughly tested and monitored after introduction.
- Urge progress on adopting condition-monitoring systems in helicopter airworthiness requirements.
- Review automatic location beacons (ADELT) in light of the beacon’s failure to operate after impact.

Aftermath
The Brent oilfield operators concluded that Chinooks were too large for offshore support tasks. The remaining Chinooks were withdrawn and sold, and the fleet’s remaining helicopters moved to non-passenger, heavy-lift work with Columbia Helicopters.

See also
- Other North Sea helicopter incidents (1986–present).