What happened
On August 6, 2010, at approximately 13:00, a Bell 206 B helicopter, registration F-HASA, was involved in a collision with an electrical power line near Arles, France. The flight was being conducted as a ferry flight (convoyage) by the pilot, who was returning to his home after canceling a scheduled aerial spraying mission due to high winds.
During the flight, the pilot intended to inspect the results of a previous spraying operation on a rice field located along his route. To perform this inspection, the pilot descended to a very low altitude, executing a bayonet maneuver with the intent of passing approximately two meters above a power line that was situated at a height of roughly seven meters. While flying at an airspeed of approximately 100 km/h, the aircraft struck the line, severing it mid-span, and subsequently collided with the ground.
The investigation
The investigation focused on the flight conditions and the pilot's maneuvers near the obstacle. Investigators established that the weather at the site was characterized by strong winds, with sustained speeds between 22 and 28 knots and gusts reaching up to 42 knots. The pilot reported that a wind gust destabilized the aircraft as it approached the field.
Furthermore, the investigation examined the pilot's recent experience and flight preparation. While the pilot was highly experienced with over 11,400 total flight hours, he had only been operating this specific helicopter for three to four days. It was also noted that no vertical reconnaissance of the field had been performed prior to the low-altitude pass.
Findings
- The primary cause of the accident was insufficient altitude margin when overflying an obstacle during periods of strong wind.
- High wind gusts (up to 42 knots) contributed to the destabilization of the aircraft during the maneuver.
- The pilot's recent experience with this specific aircraft type was limited.
- The pilot did not conduct a vertical reconnaissance of the area before attempting the low-altitude pass.