What happened
On November 12, 2013, an Airbus Helicopters AS350B3, registration F-HTOM, departed from the Mont-Dauphin Saint-Crépin aerodrome to perform external sling load operations. The flight, consisting of a pilot and a passenger, proceeded toward the Serre-Ratier site in the commune of Saint-Chally. While maneuvering over the intended cargo, the pilot initiated a right-hand turn. During this maneuver, the aircraft struck the cables of a cable car, leading to a crash that resulted in two fatalities and the destruction of the helicopter.
The investigation
Investigators examined the wreckage and found no mechanical anomalies in the airframe or engine prior to the impact. The engine was operational at the time of the collision. The investigation established that the main rotor blades, the skids, and the tail boom were all struck by the cables. At the time of the accident, the sling was not attached to the aircraft.
Regarding the site conditions, the cargo—consisting of white construction bags—was difficult to identify due to snow cover and a lack of additional marking. The cable car lines were not marked with any aviation warning lights or markers, as current regulations do not require marking for cables at that specific height. Furthermore, the cables were positioned such that they could have blended into the surrounding vegetation from the aircraft's approach path.
Data from the aircraft's flight recorders, including the VEMD and FADEC, showed no engine or system failures prior to the collision. However, the onboard video recorder (Appareo Vision 1000) failed to provide flight data because it had not recorded any information since August 2013 due to a software error that went undetected by the operator.
Findings
- The pilot likely failed to detect the cables or spotted them too late, despite being aware of their presence in the area.
- The pilot's familiarity with the site may have contributed to the decision to fly at a low altitude during this phase of the mission.
- The lack of visibility of the cables was exacerbated by the fact that they could blend into the vegetation and were not specifically marked.
- The white color of the cargo, combined with snow on the ground, made the load difficult to identify from the air.