What happened
On 25 June 2021, a Rolladen Schneider LS4-A glider, registration F-CLMF, was performing a local flight at Vinon-sur-Verdon, France. The flight began with a towed takeoff from runway 28. Upon reaching the release area at an altitude of approximately 850 m, the pilot released the tow cable.
Immediately following the release, the pilot attempted to retract the landing gear. However, during this maneuver, the aircraft's rate of descent increased sharply to approximately -6 m/s. Believing the aircraft had entered a descending air mass, the pilot turned south to clear a nearby hill and accelerated to 100 km/h in an attempt to find thermals.
As the pilot attempted to return to the aerodrome, the glider flew at a very low altitude over a wooded area. While passing over a residential area, the aircraft struck the treetops and came to a stop on private property. The impact caused the right wing to break near its root, resulting in substantial damage to the glider.
The investigation
The BEA examined the wreckage and the flight data provided by the Open Glider Network (OGN). Investigators found that the landing gear was extended and the air brakes were partially or fully extended at the time of the crash. The investigation confirmed that the air brake control linkage and the landing gear control systems were mechanically functional and that no anomalies were found in the flight control linkages.
Investigators also reviewed the cockpit configuration. While the flight manual for this specific aircraft contained an error regarding the direction of the landing gear lever, the cockpit had been updated with color-coded labels and pictograms to prevent confusion. The investigation also considered the pilot's recent flight history and the meteorological conditions, which were clear with light turbulence and no significant downdrafts.
Findings
- The primary cause of the accident was control confusion, where the pilot inadvertently operated the air brake lever instead of the landing gear lever.
- The deployment of the air brakes significantly increased the aircraft's rate of descent, which the pilot misidentified as a meteorological phenomenon (a descending air mass).
- The pilot failed to visually verify the position of the control levers or the physical state of the air brakes on the wing surfaces during the high-pressure descent.
- The sudden deterioration in performance left the pilot with insufficient time to recognize the error and correct the aircraft's configuration before the collision.