Investigation Summary
Flight 5918 was a scheduled passenger service operating in challenging weather conditions characterized by low cloud and fog. Although the crew initially climbed to 2,000 feet, they descended to 250 feet to maintain visual contact with the sea surface, as permitted under Visual Flight Rules (VFR). During the final approach phase, the helicopter entered a gradual, unrecognized descent. At 11:36 GMT, the aircraft struck the calm sea at 49°55.4′N 6°14.9′W, approximately 1.5 nautical miles northeast of the airport. The investigation determined that the pilots were attempting to fly by visual reference in deceptive visibility conditions, which led to a loss of altitude awareness. The aircraft struck the water in a controlled flight attitude, bouncing three times before rolling over and sinking. The six survivors (two pilots and four passengers) were unable to deploy lifejackets in time and instead used floating suitcases to stay afloat until rescued by RNLI lifeboats. The investigation highlighted that the helicopter lacked an audible height warning system, which could have alerted the crew to the impending impact.
Final Conclusions
The Accidents Investigation Branch (AIB) concluded that the primary cause was pilot error, specifically the commander's failure to notice and remedy an unintentional descent while flying at low altitude in poor and deceptive visibility. Contributory factors included inadequate monitoring of flight instruments and the absence of an audio height warning device. The AIB also noted that the weather minima for visual flight allowed too much discretion to the crew under such conditions. The final report was released in March 1985.
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Crew Experience
Captain
Commander for the flight; based in Aberdeen. 37 years old.
Captain
Acting as co-pilot; based in Beccles. 30 years old.
Systems & Failure Modes
Radio Altimeter
The aircraft was equipped with a radio altimeter, but it lacked an audible warning system to alert the crew when descending below a preset height.
Emergency Locator Transmitter (ELT)
No ELT was activated during the crash, and investigators noted that contemporary Royal Navy SAR helicopters were not equipped to search for civilian ELT frequencies.
Interesting Facts
- 01The aircraft was a replacement for the usual 32-seat S-61NM which was undergoing repairs.
- 02Visibility at the time of the accident was between 0.5 and 0.75 nautical miles, near the minimum for VFR.
- 03The helicopter was mechanically sound and had received its annual certificate of airworthiness only 13 days prior.
- 04Survivors used passenger suitcases as flotation aids because they could not access lifejackets.
- 05The crash was the worst British civil helicopter accident until the 1986 Chinook crash.
Safety Actions & Advisories
Mandatory Audible Height Warnings
The AIB recommended and the CAA implemented a requirement for audible height warnings on all passenger helicopters operating offshore.
VFR Weather Minima Review
The investigation led to a review of the minimum visibility and cloud ceiling requirements for helicopters operating under Visual Flight Rules.