Unlocked airbrakes deploy on winch launch, ASK 23 B porpoises

A student pilot lost control of an ASK 23 B during a winch launch at Amlikon; the glider was substantially damaged and the student uninjured. Distracted when the instructor signalled the cable was ready to hook, the student skipped the checklist item to check and lock the airbrakes. As the winch began pulling, the unlocked airbrakes self-deployed. The glider lifted to about 1 m AGL, dropped back, and porpoised four times against the grass runway, each bounce more pronounced, up to 3 m AGL. The student released the cable and the ASK 23 B came to rest on the left edge of RWY 27 with the fuselage broken ahead of the fin.

1. Solo winch launch RWY 27 in ASK 23 B: At 11:50 LT on 6 October 2012 a student pilot began a solo winch launch from RWY 27 at Flugfeld Amlikon in an ASK 23 B, his first flight in a single-seat glider.
2. Checklist skip: airbrakes not locked: While running the pre-launch checklist, the student paused to hook the winch cable and then resumed at 'Runway', inadvertently skipping the 'Brakes: checked and locked' item.
3. Airbrakes self-deploy on winch start: Once the winch began pulling, aerodynamic load on the unlocked airbrakes caused them to extend on their own; neither the student nor the instructor noticed during the launch.
4. Four porpoise bounces, up to 3 m AGL: Just after liftoff the glider bounced against the runway four times with increasing oscillation, the last reaching about 3 m AGL before it struck nose-down at roughly 30° pitch.
5. Student releases cable: Sensing the launch was abnormal after the first ground contact, the student released the winch cable; the winch driver stopped the motor once he saw the cable released.
6. Fuselage broken; no injury: The glider came to rest about 270 m from the launch point; the fuselage broke ahead of the fin, with damage to the wing root, elevator and canopy — the student was uninjured.