What happened
On April 22, 2006, a Piper J3 C 65, registration F-BFBO, was engaged in a flight from Colmar Houssen to Epinal. The pilot intended to fly over the Bonhomme ski area to show the scenery to a passenger. While flying over an ascending ski slope, the pilot spotted high-voltage power lines ahead.
Believing the aircraft was at too low an altitude to clear the lines, the pilot initiated a left-hand turn to reverse course while maintaining a climbing attitude. During this maneuver, the aircraft entered a stall. The landing gear struck the top of a tree, and the aircraft eventually came to rest ten meters away, lodged in another tree. The impact resulted in one injury and significant damage to the aircraft.
The investigation
The investigation focused on the pilot's flight preparation and the execution of the maneuver in mountainous terrain. The aircraft was operating at a high gross weight, carrying two occupants, baggage, and full fuel tanks. The investigation established that the pilot had flown the same route in the opposite direction the previous day without difficulty, as the terrain gradient was less steep in that direction. However, on this return leg, the pilot encountered much more abrupt terrain. While the pilot had noted the presence of high-voltage lines during pre-flight planning, the sudden appearance of the lines during the flight prompted the emergency maneuver.