ASW 19 mid-air collision over La Para near Château-d'Oex, Switzerland
On July 2, 1999, two ASW 19 gliders collided mid-air over La Para near Château-d'Oex, Switzerland. Both pilots were participating in a local soaring event under favorable weather conditions. During a thermaling maneuver, the gliders lost visual contact and collided. Both pilots safely evacuated using parachutes and landed without injuries. The gliders were destroyed upon impact with the ground, but no additional damage or injuries occurred.
- Thermaling climb: During an informal soaring training flight, the HB-3172 was thermaling and climbing near the ridge between Pic Chaussy and La Para after about two hours of independent soaring.
- Low pilot experience: Both glider pilots were recently licensed with relatively low total and type hours, reducing their experience in close-proximity thermaling.
- Shared thermal use: HB-1573 joined the same thermal as HB-3172, turning to the right in a good climb below and near the other glider, with both aircraft flying different orbits that could intersect.
- Loss of mutual visual: After initially sighting each other, the pilots lost visual contact and, following a brief radio position exchange, had no further visual or radio coordination while continuing to circle in the same thermal.
- Inadequate lookout above/below: The lower pilot primarily looked upward while climbing and the upper pilot, limited by cockpit blind spots and not adjusting his orbit sufficiently, had a restricted view of the glider below.
- Converging orbits: While HB-3172 had reached its ceiling altitude and HB-1573 continued climbing at about 3 m/s, their differing right-hand orbits gradually converged without either pilot fully aware of their relative positions.
- Mid-air collision: HB-1573’s left wing struck the left side of HB-3172’s cockpit in a mid-air collision over the north side of La Para, both pilots bailed out by parachute uninjured, and both gliders crashed and were destroyed on the mountainside.