What happened
On April 29, 2009, at 14:25, a Schleicher ASK 21 glider, registered F-CHIE, was performing a solo instructional flight at the Le Mazet-de-Romanin aerodrome. Due to crosswind conditions that prevented winch launching, the flight was conducted via aero-tow.
During the takeoff roll, witnesses observed the glider performing an early rotation, which led to a series of increasingly frequent bounces on the runway. The student pilot and the tow plane pilot released the cable almost simultaneously, after which the glider came to a stop on the runway. The impact caused significant damage to the forward section of the aircraft, and the pilot sustained minor injuries.
The investigation
The investigation focused on the flight dynamics during the takeoff roll and the aircraft's configuration. It was noted that the pilot's weight, including parachute equipment, was slightly above the minimum required weight for the forward seat. The aircraft's center of gravity was positioned near the rear limit of the manufacturer's allowable envelope.
Additionally, investigators examined the cockpit structure, noting that the seat attachment system used two threaded rods positioned vertically under the pilot's legs. One of these rods caused the pilot's injury during the impact. It was also noted that while Schleier had since developed an improved attachment system for newer models, the modification was not mandatory for this specific aircraft.
Findings
- The primary cause of the accident was an inappropriate application of elevator control by the pilot, who pushed the control stick forward forcefully after perceiving the glider was too high.
- The pilot failed to sufficiently account for the unusual takeoff conditions necessitated by the crosswind.
- The aircraft was operating with a center of gravity near the aft limit.