El Twin II Acro entra en pérdida en viraje bajo de ladera con descendencia

El pasajero de un Grob Twin II Acro resultó gravemente herido, el piloto levemente, cuando el planeador entró en pérdida en viraje bajo de ladera con fuerte descendencia cerca de Claro; planeador destruido. Tras casi 4 h de travesía, el piloto paró en la cresta de Parusciana por térmica débil. Siguiendo la cresta hacia el Pizzo di Molinera en amplio viraje izquierdo a 100 m AGL y 50–100 m del relieve, IAS ~90 km/h. La ascendencia débil dio paso a fuerte descendencia; ángulo de ataque y sustentación cayeron sin margen. Un boletín especial de cizalladura y turbulencia en los Alpes no fue visto; el tipo era poco manejable a baja velocidad.

1. Ridge soaring flight: After aerotow departure from Magadino and several hours of cross‑country soaring, the pilot was ridge and thermal soaring along the Parusciana area north of Castione at about 1100 m MSL.
2. Low height near slope: While following the ridge toward Pizzo di Molinera, the glider was flown at an estimated 100 m above ground and 50–100 m laterally from the slope, leaving little margin for recovery.
3. Inadequate speed margin: The pilot flew at about 90 km/h in conditions with forecast wind shear and turbulence, without increasing speed above normal minima despite the low altitude and mountain environment.
4. Encountered strong sink: During a wide left turn following the ridge, the glider transitioned from weak lift into a strong downdraft, abruptly reducing angle of attack and lift at an already low airspeed.
5. Stall and loss of control: At low speed and low height, the glider stalled and the pilot lost control, with insufficient altitude available for recovery.
6. Crash - serious injury: The stalled glider descended into the forested slope near Claro, destroying the aircraft, seriously injuring the front‑seat passenger and slightly injuring the pilot.