A report by the Department of Transport’s Air Accident Investigation Unit shows that the helicopter was flying well below the required altitude of 500ft in poor visibility at the time of the crash.
The accident occurred when the Robinson R44 Raven helicopter crashed in woodland in the Slieve Aughty mountains close to a windfarm site at Derrybrien, Co Galway, on July 9, 2005.
Two of the helicopter’s three occupants were killed in the crash. They were passenger Mark Reilly, a publican and father of three from Galway city and pilot, Damien Bergin from Castlerlakeney, Co Galway who both died from injuries sustained in the crash.
Another passenger, Mike Givens from Oranmore, Co Galway, received serious injuries but survived.
Mr Bergin managed to alert rescue services to the accident by mobile phone.
The three friends were on a flight between New Ross, Co Wexford and a base near Galway Airport on their return from a visit to the Tall Ships Race in Waterford.
People living near Derrybrien reported poor visibility and low cloud in the area at the time of the accident.
A witness on the ground told investigators that he saw the helicopter pass near the wind farm at around 10.43am before hearing“a loud bang followed bysilence.”
Mr Givens told AAIU inspectors that the helicopter had suddenly entered cloud shortly before the accident.
“We seemed to hit something and I saw Damien struggling with the controls. I remember that we went chopping through trees before coming to an abrupt halt,” said Mr Givens who became unconscious shortly after the crash.
Inspectors found no evidence that there had been any contact between the helicopter and the wind turbines at Derrybrien.
The report noted that the pilot was “not experienced”. It claimed a contributory factor in the accident was the pilot’s decision to continue on his chosen flight path below the recommended visibility limit.
Investigators believe he became spatially disoriented which resulted in an unintentional loss of height, leading to a collision with the ground.
Weather conditions were believed to a major contributory factor in all three fatal aviation accidents in the Republic during 2005.
The AAIU has recommended the Irish Aviation Authority revise its advice to pilots to emphasise the dangers of an over-reliance on GPS equipment in poor visibility conditions.