What happened
On April 14, 2004, a Jodel D 140 E F-POPN, operated by a flying club, was performing a mountain flight instruction mission. The crew, consisting of an instructor and a student pilot, had departed from the Méribel altiport to perform several landings on various glaciers in the Haute Tarentaise region. After completing two reconnaissance turns, the aircraft landed on the Grande Motte Glacier at approximately 11:50.
During the subsequent takeoff attempt, the student pilot followed existing tracks in the snow and applied maximum power. As the aircraft accelerated, the instructor noted that the amount of sliding felt less significant than during previous takeoffs. Approximately 150 meters after applying full power, the student requested guidance. Believing the surface friction was insufficient to ensure a safe takeoff, the instructor ordered the takeoff to be aborted. The student reduced power to idle, but the aircraft continued to accelerate along the existing tracks.
In an attempt to stop the aircraft, the instructor instructed the student to unbuckle and exit the cockpit. The instructor opened his canopy and jumped in front of the right wing, attempting to use his weight to pivot the aircraft, but the maneuver failed. The student exited behind the left wing after switching the magnetos to the OFF position. Despite both crew members attempting to physically restrain the aircraft, the F-POPN continued to slide down the glacier, eventually coming to a halt against rocks approximately 100 meters below the glacier's edge. The aircraft was destroyed.
The investigation
The investigation focused on the decision-making process during the takeoff roll and the physical conditions of the glacier surface. Investigators examined the slope of the Grande Motte Glacier, noting that while the upper section has a gentle gradient, the lower section increases significantly to a 30% slope. The investigation also looked into the instructor's recent flight history and the changing state of the snow surface.
Findings
- The primary cause of the accident was the inappropriate decision to evacuate the aircraft while it was still in motion during the takeoff roll.
- The instructor had misjudged the level of sliding friction available on the snow surface.
- The instructor's ability to perform flight instruction was likely degraded by end-of-season fatigue and the routine of high-frequency operations, having completed 689 landings in the preceding 90 days.
- The snow conditions had changed since earlier that morning, becoming less slippery, a phenomenon that is difficult to predict.