ASK 13 wing strikes trees on low, slow final after misjudged circuit

An instructor and student in an ASK 13 were lightly and seriously injured when the right wing struck treetops on a low, slow final after the pattern altitude was misjudged; destroyed. After a winch launch in light easterly wind on a training flight (student up front, instructor in back), the circuit was uneventful. The instructor announced landing on RWY 29; witnesses then saw the glider on final over the trees east of the airfield strikingly low and slow. It banked right, the right wing struck treetops in a ~20 m stand and the glider fell almost vertically into the forest ~200 m east. No technical faults; mass and CG within limits.

1. Winch launch + uneventful circuit: Winch launch in direction 290° at Butzbach for a training flight; student in front, instructor in back. Light easterly wind; no anomalies up to the landing pattern.
2. Pattern altitude misjudged: In the landing pattern, available height was misjudged, putting the glider too low over the wooded area east of the field.
3. Low, slow final over trees: Witnesses observed the glider strikingly low and slow on final over the ~20 m tree stand east of the airfield.
4. Right wing strikes treetops: At insufficient airspeed close to the trees, the glider banked right; the right wing contacted the treetops.
5. Near-vertical fall, branches brake it: The glider pitched into a steep, almost vertical descent, decelerated partly by further contact with branches.
6. Vertical impact ~200 m east of field: The glider impacted the ground almost vertically in mixed forest about 200 m east of the airfield; the student (front) was seriously injured, the instructor (rear) lightly injured.