What happened
On May 1, 2010, a Robinson R44 helicopter, registration EI-SUB, was participating in a private flight near Moll’s Gap, Co. Kerry. The aircraft was positioned on an elevated crest in mountainous terrain, where the crew had been acting as officials for a car rally.
As the helicopter lifted off from the crest and initiated a right bank, the main rotor blades made contact with two disused overhead electrical cables. These cables, which crossed the road approximately 10 meters from the takeoff point, were positioned at a height of roughly 7 meters. The impact severed the cables. Following the strike, the pilot performed a controlled emergency landing approximately 80 meters from the cables. There were no injuries to the two occupants, though the aircraft sustained significant damage to its main rotor blades.
The investigation
The investigation focused on the sequence of events leading to the contact and the visibility of the hazard. Investigators examined the aircraft's condition and the environmental context of the takeoff. The inspection of the rotor blades by the manufacturer confirmed that the impact did not cause a sudden stoppage of the rotor system. The investigation also noted that the pilot had identified the cables prior to departure but failed to maintain visual contact with them during the maneuver.
Findings
- The primary cause of the accident was the pilot's loss of situational awareness regarding the cables' location during the takeoff and banking maneuver.
- The dark green and brown landscape of the mountainous terrain made the cables and their supporting poles extremely difficult to distinguish.
- The aircraft's main rotor blades suffered damage to the leading edges and lower surfaces, leading to the blades being written off.
Safety action
While this incident was part of a series of cable strikes in Ireland during a 13-month period, the investigation did not result in new safety recommendations, as the Irish Aviation Authority (IAA) had already implemented a safety awareness campaign and poster regarding wire strike hazards.