What happened
On July 1, 2015, a Jodel D1-40C, registration F-BMFT, departed from Grenoble Le Versoud for a series of landings at various altisurfaces. After visiting Superdévoluy and Clamensane, the pilot proceeded toward the Banon altisurface.
The pilot performed several reconnaissance passes over the landing area, initially at 660 ft and later at approximately 300 ft. Following a low-level pass along the runway, the aircraft joined the base leg for runway 35. As the aircraft approached the runway threshold, approximately 200 meters from the surface, the pilot initiated a go-around. During the climb, the aircraft struck trees at the end of the runway and entered a left turn. The pilot was unable to maintain control, and the aircraft subsequently struck trees again before impacting the ground.
The investigation
The investigation utilized data from an ISEI Safety Plane flight recorder, which provided real-time tracking of the aircraft's trajectory, engine parameters, and airspeed/groundspeed. Analysis of the wreckage revealed that the engine was producing power at the time of impact, with the throttle forward, mixture pulled, and carburetor heat on. The electrical pump was active, and the fuel selector was set to the rear tank. The flaps were extended.
Investigators also examined the environmental conditions. At the time of the accident, surface winds were reported between 5 and 15 knots from the southeast, though local observations varied. The terrain features a ridge to the east of the final approach, and the runway itself has a significant 11% gradient.
Findings
- The approach was unstabilized, as evidenced by an increasing groundspeed during the final approach leg, likely caused by a tailwind component or thermal updrafts from the surrounding terrain.
- The initial reconnaissance maneuvers were insufficient for the pilot to accurately assess the wind conditions or identify all necessary elements for a stabilized approach.
- The primary cause of the accident was the pilot's decision to continue the approach rather than executing a go-around prior to the descent phase.