What happened
On October 3, 2012, at 14:20 local time, a Grumlam G164 B, registration F-GVDJ, was performing agricultural spraying operations north of Aigues-Mortes. The pilot had departed from Montpellier Candillargues earlier that afternoon to treat a specific field oriented northeast/southwest.
During the mission, the pilot approached the target area from the southwest, passing over two distinct sets of power lines. The first set, consisting of pylons approximately 7 meters high, sat on the southwest edge of the field, perpendicular to the flight path. A second, larger, and more massive power line ran nearly parallel to the first, located about 300 meters to the southwest. While the pilot initially identified both lines during a preliminary reconnaissance, the aircraft subsequently collided with the cables at an altitude of approximately 6 meters.
The impact dragged the wires for roughly 140 meters, toppling two concrete pylons, before the aircraft crashed into a grove of trees. The aircraft was destroyed in the impact.
The investigation
The investigation focused on the flight path, the aircraft's condition, and the environmental factors present at the time of the accident. Examination of the wreckage revealed impact marks on both the left and right wing struts.
Investigators analyzed the solar position, noting that the sun was at an elevation of 41° and an azimuth of 196°. The pilot, who had extensive experience including 1,500 hours on this aircraft type, reported that the sun was positioned almost directly in his line of sight during the critical phase of the flight, causing significant glare. Additionally, the investigation reviewed the pilot's flight schedule, noting that he had already completed nearly five hours of spraying operations earlier that day.
Findings
- The primary cause of the accident was the pilot's confusion between the two sets of power lines.
- While the pilot had correctly identified the lower power lines during his initial reconnaissance, the glare from the sun caused him to focus his attention on the more massive, secondary power line instead of the obstacle directly in his path.
- The low altitude maintained during the spraying operation did not provide sufficient clearance to safely clear the obstacles.
- Fatigue resulting from the pilot's workload throughout the day may have contributed to a momentary lapse in vigilance.