What happened
On June 19, 2012, an Air Corps EC135P2+ helicopter, operating as an air ambulance, was conducting an emergency medical mission to transport a patient near Borrisoleigh, Co. Tipperary. The flight had departed from Athlone to collect a patient from a road ambulance at a pre-arranged location near the Currabaha crossroads.
As the aircraft performed its final approach to a landing site in a nearby field, the main rotor blades struck two 20 kV overhead power lines. The impact severed the wires and triggered intense vibrations throughout the airframe. The pilot was forced to execute an immediate, heavy landing. Although the aircraft suffered substantial damage, the three crew members were able to exit the helicopter without injury.
The investigation
The AAIU investigation examined the flight sequence, the landing site selection, and the communication between the aircrew and ground personnel. Investigators looked into the reconnaissance patterns flown by the pilot and the visibility of the obstacles during the approach. The probe also reviewed the safety protocols regarding the coordination between the National Ambulance Service and the Air Corps during Emergency Aeromedical Support (EAS) missions.
Findings
- The primary cause of the accident was the rotor blades striking electrical wires crossing the approach path.
- The pilot and crewman identified the wires only 0.8 seconds before impact, leaving insufficient time for evasive maneuvers.
- Ground personnel, including an Advanced Paramedic, had observed the wires prior to the helicopter's arrival but lacked a direct method of communication to alert the flight crew.
- The wires were difficult to detect due to the light breeze and the rural background.
- One crew member was not properly secured in their seat with a four-point harness, resulting in them being thrown during the impact.
- The existing risk register for the mission had deficiencies regarding the analysis of wire strike hazards.
Safety action
Following the investigation, several safety recommendations were issued to prevent similar occurrences:
- Expanding the use of Tetra radios to paramedics to ensure direct communication with helicopter crews.
- Implementing aviation hazard awareness training for ground-based medical staff.
Reviewing Air Corps procedures for risk register compilation, mission training syllabi, and landing site reconnaissance patterns.