What happened
On October 18, 2000, at approximately 12:30 local time, an Aérospatiale SA 315B Lama, registered F-GECT, was engaged in utility flight operations near the Col de Maronne in the Auris-en-Ois/Alpe d'Huez region. The pilot had been performing approximately fifteen rotations over a three-hour period, transporting materials between a concrete plant and the foundations of a ski lift pylon.
Following a third refueling stop of the morning, the pilot began a descent back toward the concrete plant. During this maneuver, the pilot failed to identify the presence of high-voltage power lines supplying the Alpe d'Huez ski station. Although the pilot attempted an evasive maneuver upon late detection of the wires, the main rotor struck the cables, severing three electrical lines and causing heavy damage to one main rotor blade. Despite the impact, the pilot maintained control of the aircraft and performed a landing on level ground approximately 150 meters below the site of the collision.
The investigation
The investigation focused on the flight path and the pilot's awareness of obstacles during the descent following refueling. Investigators examined the aircraft's condition and the environmental factors present at the time of the accident. Meteorological conditions were reported as CAVOK (ceiling and visibility OK) with calm winds, providing clear visual conditions for flight.
Findings
- The primary cause of the collision was a decrease in vigilance by the pilot during the descent.
- The pilot failed to maintain adequate scanning for obstacles, specifically the high-voltage lines, after completing the refueling task.
- The impact resulted in the severing of three electrical cables and significant damage to the aircraft's main rotor blade.