What happened
On May 13, 2021, a Bell 47 helicopter, registration F-GKTR, was performing aerial spraying of a larvicide product over a marshy area adjacent to the A43 motorway in Planaise, France. During a preliminary reconnaissance flight at approximately 200 feet, the pilot identified high-voltage power lines crossing the area perpendicularly to the highway.
To avoid the risk of spraying chemicals onto the motorway and potentially distracting motorists, the pilot decided to deviate from standard procedures. Instead of flying parallel to the power lines, the pilot chose a flight path parallel to the highway, which meant flying perpendicular to the cables. While focused on maintaining a precise trajectory to avoid the road, the pilot lost situational awareness regarding the lines. At an altitude of approximately 40 meters, the aircraft struck the high-voltage cables. The impact shattered the cockpit bubble and caused the helicopter to enter a rapid yaw rotation. Despite the loss of control, the pilot maintained a level longitudinal attitude until the aircraft impacted the marshy ground near the edge of the motorway. The crash resulted in one injury (the pilot) and the destruction of the aircraft.
The investigation
The investigation focused on the flight path, the wreckage, and the pilot's decision-making process. Examination of the wreckage revealed that the tail boom had separated from the fuselage, the forward section was destroyed, and the rear transmission unit was missing. While the three high-voltage cables were not severed, several were damaged by the impact and the friction of the main rotor blades. The investigation also noted that the attachment for one of the main rotor blades had broken.
The pilot, a 29-year-old commercial pilot with 450 total flight hours, provided testimony indicating that he had previously worked this specific plot. He confirmed that he intentionally chose the perpendicular flight path to prioritize the safety of motorists on the A43, though he admitted to overestimating the risk to drivers relative to the danger posed by the power lines.
Findings
- The pilot's decision to fly perpendicular to the power lines departed from standard spraying procedures, which dictate flying parallel to such obstacles to reduce the pilot's workload and environmental monitoring requirements.
- The pilot's focus on maintaining a precise spray pattern to avoid the motorway led to a loss of attention regarding the presence of the electrical lines.