ASH 25 strikes a tree in a low turn along a rising mountain ridge

An ASH 25 was substantially damaged when it struck a tree in a low turn while ridge soaring on an instructional mountain flight. With a student under instruction aboard, the glider slipped to the lee of a ridge and met strong sink; the instructor took control, regained the windward side and soared the crest only 50 to 100 m above it in a 20-25 kt south-easterly. As the terrain rose the margin shrank, and rather than turn back he turned right toward a sunlit valley he expected to work. The climb did not come; the glider clipped an oak and hit the ground about 30 m on, stopping in broom. Both occupants were unhurt.

1. Ridge soaring, dual instruction: On an instructional mountain flight, a student under instruction with an instructor soared the ridges after an aerotow.
2. Lee-side sink; instructor takes over: The glider slipped to the lee of a ridge and met strong sink, and the instructor took control and regained the windward side.
3. Low margin as the crest rose: He soared north along the crest only 50 to 100 m above it in a 20-25 kt south-easterly, and the margin shrank as the terrain rose.
4. Turned toward a sunlit valley for lift: Rather than turn back into the known sink, he turned right toward a sunlit valley he expected to give lift.
5. Clipped a tree, hit the ground: The expected climb did not come; the glider clipped the top of an oak and hit the ground about 30 m on, stopping in broom; substantially damaged, both occupants were unhurt.