What happened
On April 7, 2015, a Christen Husky A-1, registration F-GMGG, was performing a training flight from the Méribel Altiport in France. The crew, consisting of a pilot and an instructor, intended to fly to Tignes and around Mont Blanc.
The aircraft had been parked overnight on the snow with its skis in the downward position. On the morning of the flight, the skis had frozen to the ground, requiring assistance from a third party to manually lift the wings and break the ice adhesion.
During the takeoff roll, the pilot applied full power. However, the takeoff run was longer than expected, and the aircraft failed to accelerate or climb effectively. The aircraft drifted to the left of the runway centerline and struck trees at the end of the strip. The impact caused the aircraft to fall vertically and catch fire, though the crew managed to evacuate before the aircraft was destroyed. The pilot and instructor sustained serious injuries.
The investigation
The BEA examined the wreckage and found that the engine was functional, with the propeller blades showing evidence of power delivery at the time of impact. While a possible oil leak was noted, it did not affect engine performance.
Investigators determined that the aircraft was overweight, with a takeoff mass of approximately 930 kg, exceeding the maximum allowable takeoff mass of 1,980 lbs (898 kg) by about 30 kg. Additionally, the investigation focused on the condition of the skis and the takeoff performance on the snowy surface.
Findings
- The pilot failed to perform a weight and balance calculation prior to departure, which would have revealed the overweight condition and allowed for a reduction in fuel load.
- The skis were likely contaminated with ice from the overnight freezing, which increased friction and reduced acceleration during the takeoff roll.
- The combination of the excessive weight and the reduced acceleration caused by the contaminated skis resulted in an insufficient climb gradient to clear obstacles at the end of the runway.