Duo Discus drifts into a ridge in lee-side sink on a mountain soaring flight

A Duo Discus was substantially damaged when it drifted into a mountainside on a discovery flight. After an aerotow release near a col at about 1,700 m, the pilot soared the ridges but found the air too turbulent in a gusty, strengthening south wind and turned back. Retracing his earlier route along the relief, he met lee-side sink and a strong crosswind; the glider drifted toward the rock face and did not respond to full opposite aileron. It struck the slope near 1,660 m, bounced and spun round before stopping against the mountain. The pilot knew to avoid the spot in strong south wind but had not realised how fast conditions changed.

1. Ridge soaring, discovery flight: On a discovery flight with a passenger, the pilot soared the slopes north of the col after an aerotow release at about 1,700 m.
2. Turbulent, strengthening south wind: The glider would not climb and the south wind became gusty and choppy; the pilot turned back for the passenger's comfort.
3. Lee-side sink on the return: Retracing his earlier route along the relief, he met lee-side sink and a strong crosswind.
4. Drifts toward the rock face: The glider suddenly drifted toward the rock face and did not respond to full opposite aileron.
5. Struck the slope: It struck the slope near 1,660 m, bounced and spun round before stopping against the mountain; substantially damaged, the two occupants were unhurt.