What happened
On November 7, 2011, an Eurocopter AS 350 B3, registration HB-ZGI, was engaged in a commercial filming operation near Ardez, Switzerland. The mission involved capturing high-quality, close-up footage of a convoy of vehicles, including a sports car and an off-road vehicle with a trailer, traveling along a winding mountain road.
To ensure optimal film quality, the mission plan called for the helicopter to fly at very close proximity to the vehicles, sometimes as close as 3 to 5 meters from the car roofs. During the final sequence, the pilot was attempting to maintain a tight formation with a sports car. During a maneuver, the pilot momentarily lost visual contact with the vehicle as it braked while passing behind several rock towers. As the car reappeared just below the helicopter's position, the pilot immediately attempted to close the gap to maintain the required filming distance. During this maneuver, the main rotor blades struck a rock face, causing the aircraft to lose control and impact the ground.
The investigation
The Swiss Transportation Safety Investigation Board (SUST) examined the flight sequence, the aircraft configuration, and the crew's actions. The investigation included an analysis of film footage from the mission, interviews with the crew and witnesses, and a review of the aircraft's technical state.
Investigators looked into the cockpit environment, noting that a specialized camera system and a monitor were installed on board. The investigation also reviewed the pilot's visual perception, specifically how the focus on the filming subject and the physical obstructions in the cockpit—such as the passenger's stature and the monitor setup—might have affected the pilot's ability to monitor terrain clearance.
Findings
- The primary cause of the accident was the failure to maintain sufficient distance from the terrain, leading to the main rotor striking a rock wall.
- The pilot's attention was heavily focused on the camera work and maintaining the desired distance from the vehicles, which led to a decrease in monitoring the proximity to obstacles.
- The pilot did not break off the filming sequence or increase altitude after losing visual contact with the lead vehicle.
- The physical configuration of the cabin, including the monitor and the passenger's position, restricted the pilot's peripheral vision on the left side.
- There were no technical failures or mechanical issues identified in the aircraft prior to the collision.
- The weather conditions were favorable for flight, with good visibility and no significant meteorological interference.