ASK 23B student enters inverted spin before pattern; possible low-g sensation push

A ~16 h student on his 16th solo was fatally injured when an ASK 23B departed controlled flight before the pattern at Buttwil and entered a sustained inverted spin; destroyed. Returning from a 2-h solo task, the glider was seen in a left slip-like attitude with the left wing dropping; the nose dropped fast and it pitched forward over nose and left wing, losing only 50-100 m before settling into an inverted spin with no recovery inputs. Bruising on both hands suggested stick injuries. The 'sub-gravity sensations' phenomenon — pushing the stick forward in low-g and panicking into more forward stick — may have played a role. No technical faults.

1. Solo 2-hour task; returning to field: Student on 16th solo (~16 h total, learner's permit) aerotowed at 13:13 from Buttwil for a 2-hour solo soaring task; returning to land after about 2 h.
2. Low-g (sub-gravity) sensation hypothesis: In low-g, inexperienced pilots can read the falling sensation as dangerous and push the stick forward — the trained stall/spin recovery — entering a cycle of panic and further forward stick.
3. Left slip-like attitude before pattern: At about 500-600 m AGL before the pattern, witnesses saw the glider enter a left side-slip, left wing dropping; airbrakes in a fast slip can pitch the ASK 23 down hard.
4. Forward pitch over nose + left wing: Nose dropped fast; the glider pitched forward over the nose and left wing, losing only 50-100 m of height; airspeed barely increased.
5. Sustained inverted spin develops: The forward pitching settled into a sustained inverted spin (Rückenvrille) with constant pitch attitude, rotation rate, and sink; no recovery inputs were observed.
6. Bruising on both hands: Both hands bruised between thumb and index; post-mortem interpretation: stick injuries.
7. Inverted impact in a field: The glider impacted a field still in the inverted spin attitude; the pilot was fatally injured and the airframe destroyed. The ASK 23 is not certified for inverted flight.