What happened
On August 13, 2017, a Paul Siebert KA 6 CR glider, registration F-CJJD, was preparing for a winch launch from runway 32 at the Florac Sainte-Énimie aerodrome. After the pilot requested the cable be tensioned, the winch operator began the launch. The glider accelerated and lifted off the ground at approximately 60 km/h.
While the pilot was attempting to level off to gain airspeed, the aircraft experienced a sudden decrease in acceleration. The pilot observed the cable parachute beginning to deploy, indicating a loss of tension. Having kept a hand on the release handle throughout the takeoff, the pilot immediately released the cable at an estimated altitude of only 2.5 meters. Due to the extremely low altitude and low airspeed, the pilot was unable to establish a nose-down attitude to accelerate. Consequently, the right wing dropped and struck the ground, causing the aircraft to perform a nose-over (pitch-over) before coming to rest approximately 200 meters from the launch point.
The investigation
The investigation focused on the sudden loss of tension in the winch cable. The pilot reported that the weather conditions were clear with light, variable winds. The investigation confirmed that the cable was properly attached to the glider's release hook. The winch used was a Skylaunch electric model, and no prior incidents with this specific equipment were reported. The investigation examined the sequence of the release and the aerodynamic state of the Paul-Siebert KA 6 CR at the moment of impact.
Findings
- The primary cause of the accident was a sudden decrease in winch cable tension, which triggered the deployment of the cable parachute.
- The low altitude at the time of the release prevented the pilot from maneuvering the aircraft into a dive to regain airspeed.
- The loss of lift caused the right wing to stall and strike the ground.
- A tailwind gust may have contributed to the reduction in cable tension, though the exact cause of the tension loss could not be definitively determined.