An Irish Coast Guard helicopter was involved in a potentially dangerous incident while flying over Northern Ireland earlier this year when it exceeded its maximum speed due to turbulence.
An investigation by the UK Air Accidents Investigation Branch (AAIB) claimed the helicopter had probably flown through mountain waves when passing the Sperrin Mountains which created the turbulence.
The incident occurred on February 5th when the Sligo-based Sikorsky S-92A helicopter was about five miles north-east of City of Derry Airport on a search and rescue training flight to rendezvous with a lifeboat at Portrush, Co Antrim.
No injuries were reported among the four crew on board and the flight made a precautionary diversion to the City of Derry airport without further incident.
An inspection of the helicopter found some damage with the need for some components to be replaced, but it was returned to service two days later.
However, it is believed that the damage to the helicopter, which was manufactured in 2006, may have pre-existed the actual incident.
Although there was a forecast of moderate turbulence in the region, the AAIB report said the Irish Coast Guard helicopter encountered unexpected severe turbulence which resulted in its indicated air speed reaching 175 knots or 324km/h which triggered an “airspeed” warning sound.
The crew described how the Sikorsky originally pitched up momentarily before pitching down and accelerating.
The commander of the helicopter reported that all crew felt a noticeable increase in vibrations of the aircraft’s frame.
The AAIB report noted the crew had reviewed the weather before the flight, and it found conditions were “more than adequate for the planned route.”
The report is one of the first relating to an Irish Coast Guard helicopter since an investigation into the fatal accident involving a similar model with call sign Rescue 116 which crashed off the Co Mayo coast on March 14th, 2017 with the loss of all four crew members on board.
The Irish Coast Guard has been contacted for comment.
