Twin Astir multiple ground impacts after pilot impaired in winch abort

A Grob G103 Twin Astir II on a solo winch launch at Seighford was substantially damaged; the pilot was seriously injured. At ~60 m AGL a loud bang was heard and, assuming a weak-link break, the pilot pitched down aggressively to abandon (dust rose under negative g). The cable then back-released from the belly hook. The pilot then became briefly impaired — conscious but unable to control pitch or airbrakes; the cause was not established. The glider oscillated in pitch, struck the ground, bounced and impacted twice more; the fin and tailplane broke away. AAIB cited the brief impairment of unknown origin.

1. Solo winch launch from front seat: Grob G103 Twin Astir II (G-CKRH, built 1981, SN 3596) on a solo winch launch from Seighford Airfield. Pilot 60 yo, SPL, 181 h total / 45 h on type, 9 h in last 90 days, 1 h in last 28 days. Flying from the front seat. Glider had been recently refurbished with new energy-absorbing seat cushions and seat harnesses.
2. Loud bang at ~200 ft AGL: Launch began normally with the glider pitching into a nose-up attitude. At ~200 ft AGL the pilot heard a 'loud bang' and assumed the winch cable's weak link had broken. AAIB analysis: the noise may have been the cable's ring moving under load within the jaw of the hook as the glider climbed through the wind gradient (no abnormality identified in the cable assembly).
3. Pitch-down to abandon (judged excessive): The pilot lowered the nose to abandon the winch launch. He observed dust from the cockpit floor rising into his vision due to negative g and judged that his pitch-down input was excessive.
4. Cable back-released from belly hook: The winch cable released from the belly hook. Post-accident inspection found the weak link intact and the cable in good condition — consistent with a back-release (the safety mechanism on glider winch hooks that releases the cable without pilot command when a rearward load acts on it; in an abandoned launch, aerodynamic drag on the cable can produce this).
5. Pilot briefly impaired, cause unknown: Shortly after the abandonment the pilot became briefly impaired — he remained conscious throughout but was unable to control the glider's pitch attitude or open the airbrakes. CAA Medical Department: brief negative g was insufficient to cause incapacitation; vestibular system unlikely affected by recent flu-like illness (the pilot had been ill 7-11 October, accident flight was his first since). Paramedics noted low blood O2 at site; oxygen administered for 2 days in hospital. Cause of impairment not established by AAIB.
6. Pitch oscillation, airbrakes retracted: With the pilot impaired and unable to operate controls, the glider was observed to oscillate in pitch with airbrakes retracted.
7. Multiple heavy impacts, fin detached: The glider struck the ground in a level attitude, bounced back into the air, and impacted the ground twice more. During the final impacts the fin and tailplane broke away from the fuselage at the base of the fin. Pilot seriously injured. Aircraft substantially damaged (fin detached, damage to nose and forward cockpit). AAIB conclusion: accident occurred because the pilot became briefly impaired following his decision to abandon the winch launch; the impairment prevented him from controlling the pitch attitude and airbrakes; reason for the impairment was not established.