Off-axis winch cable veers an SZD-51-1 off a mountain strip
An experimental trial of winch-launching gliders from the Croix-de-Coeur mountain airstrip above Verbier left the pilot of an SZD-51-1 seriously injured and the glider substantially damaged. The French slope-launch winch had its return pulley set right of the runway axis, so the cable pulled the glider off-axis. Accelerating over a storm-rutted strip into a ~20 km/h tailwind, it drifted left, then swung sharply right at a change of slope as the off-axis pull took over. Below flying speed and violently shaken, the pilot could not reach the release; the glider struck rough ground and stopped off the runway.
- Winch launch ground roll: During a test winch launch from the Croix-de-Coeur mountain site, the SZD-51-1 began its ground roll on a short, uneven, slightly downhill strip with a significant tailwind.
- Glider yaws off axis: As the glider accelerated over a bump where the slope changed, the off-axis winch cable, routed via a pulley right of the runway, caused it to yaw suddenly 20–25° to the right.
- High tailwind component: A tailwind of about 20 km/h reduced the effective airspeed gained during the limited usable ground run, making it harder to reach takeoff speed.
- Degraded short runway: Only about the first 100 m of the 200 m natural strip were marginally usable, with the remainder increasingly rough and eroded, limiting acceleration and increasing drag and shocks.
- Right-side pulley position: The winch cable ran through a pulley 13 m right of the runway axis, against the flight manual's requirement that it not pass right of the center hook, creating a lateral pull.
- Pilot continues launch: Believing liftoff was imminent, the pilot did not release the cable, then, shaken violently on the rough ground, was unable to operate the release and lost directional control.
- Crash - serious injury: Still below flying speed, the glider was deflected off the strip, braked hard by rough terrain; the cable broke and it stopped badly damaged in grass, the pilot seriously injured.