What happened
On 8 February 2004, a Rallye 100 ST, registration EI-BFP, was conducting a private flight near Clonlara, County Clare. The pilot, accompanied by one passenger, had planned to land in a local field after receiving permission from the landowner. Prior to the flight, the pilot had performed a ground reconnaissance of the site, during which two sets of ESB power cables were noted running across the field. However, the pilot did not observe any other cables during this initial inspection.
After departing from Coonagh Airfield, the pilot performed a low-level reconnaissance of the intended landing area at altitudes between 20 and 25 feet. During this maneuver, the pilot identified a set of power cables directly in the flight path. In an attempt to avoid the wires, the pilot pitched the aircraft downward. While the cables cleared the propeller and canopy, the aircraft experienced sudden, violent pitching movements. The pilot immediately applied full power and diverted the aircraft back to Coonagh Airfield, where it landed safely without further incident.
The investigation
The investigation focused on the physical damage to the aircraft and the circumstances surrounding the cable strike. Post-flight inspections of EI-BFP revealed that the leading edge cowling of the vertical tail fin had been struck by the cables. Additionally, the port mass balance horn of the elevator sustained impact damage, and the VHF antenna, positioned forward of the vertical fin, was severed at its base.
The investigation also examined the impact on local infrastructure. The strike severed two 10,000-volt cables, necessitating repairs by the ESB and resulting in a power outage for approximately 60 to 80 homes lasting 21 hours. The pilot identified several contributing factors, including the fact that the utility poles were obscured by trees and hedgerows, and that visibility was hampered by the low position of the sun. The pilot also acknowledged that the initial ground survey of the field was insufficient.
Findings
- The primary cause of the incident was the aircraft striking 10,000-volt power cables during a low-level approach.
- The pilot's ground reconnaissance failed to identify all hazards because the utility poles were hidden within vegetation.
- Low sun angles contributed to impaired visibility during the low-level reconnaissance.
- The pilot failed to conduct a comprehensive foot survey of the entire landing site.
- The aircraft avoided a more catastrophic outcome because the cables cleared the propeller and canopy and snapped upon hitting the vertical fin.