What happened
On July 23, 2012, an instructor and a student pilot were conducting a mountain flying training flight in a Christen Industries A1 Husky, registration F-GRTJ. The flight crew arrived at the Clamonsane altisurface in the Alpes-de-Haute-Provence region for a scheduled stop. During the approach to the unpaved runway, the crew performed a reconnaissance and estimated the wind to be approximately 5 knots from 050°.
As the aircraft transitioned to the landing flare, a wind gust caused the aircraft to touch the runway and bounce. The instructor, seated in the rear, took control of the aircraft. Upon the second touchdown near the top of the runway's slope inversion, the instructor determined that the aircraft's speed was too high to stop before the end of the runway. Consequently, the instructor initiated a go-around. During the application of power, the acceleration felt less forceful than usual, though the engine power appeared normal. The aircraft drifted toward the right edge of the runway, and while the instructor corrected the trajectory, the aircraft lifted off near the end of the runway. The aircraft subsequently struck a fence and the left wing collided with the top of a tree, causing the aircraft to come to rest in the trees. The aircraft sustained heavy damage.
The investigation
Investigators examined the wind conditions reported by other pilots present at the airfield that day. One pilot reported experiencing sudden, strong updrafts during his approach, which forced him to perform two separate go-arounds. A second pilot noted observing a tailwind during his reconnaissance and experienced significant turbulence on final approach, requiring frequent power adjustments to maintain his target touchdown point. This pilot also noted that the windsock indicated an irregular tailwind of 5 to 10 knots.
Findings
- The crew underestimated the aerological effects (wind conditions) during the approach to the mountain landing strip.
- The aircraft experienced a bounce during the landing flare due to a wind gust.
- The decision to perform a go-around was prompted by excessive speed and the risk of overrunning the runway.
- Wind conditions at the airfield were more turbulent and included tailwind components than the crew had initially estimated.