What happened
On May 14, 2011, at 14:40 local time, a Scheibe SF 28 motor glider, registration F-CFTU, was performing a local flight from the unpaved runway 35 at the Bédarich La Tour-sur-Orb aerodrome. The pilot, accompanied by a passenger, initiated takeoff using full engine power. The pilot reported no engine malfunctions during the initial climb.
As the aircraft reached an altitude of approximately 5 meters with an indicated airspeed of 90 km/h, it encountered a gust of wind from the left. This gust pushed the aircraft to an altitude of 10 meters and caused it to drift significantly to the right of the runway centerline. The aircraft subsequently entered a stall and collided with nearby trees. An eyewitness, a pilot flying another motor glider in the area, observed the aircraft depart from the runway axis with oscillations before stalling and falling into the trees.
The investigation
The investigation examined the aircraft's configuration, noting that the mass and center of gravity were within the manufacturer's specified limits. The pilot had approximately 880 total flight hours, including 37 hours on this specific type.
Meteorological conditions at the time included a north-westerly wind of 18 kt. While the flight manual does not specify a maximum crosswind limit for takeoff, the investigation reviewed manufacturer recommendations regarding turbulence. The importer of the aircraft in France suggests that while a climb speed of 90 km/h is recommended in calm conditions, pilots should add half the strength of any gusts to the indicated airspeed when turbulence is present.
An experienced instructor of the same aircraft type noted that the Scheibe SF 28 experiences a progressive stall, often feeling more like a sink, with a stall speed of approximately 60 km/h.