El LS 3 entra en espiral cerrada desde un viraje bajo con viento del noreste racheado
El piloto de un LS 3 murió cuando el planeador entró en espiral en un viraje bajo con nordeste racheado cerca de St-Imier y se estrelló en un vallón boscoso; planeador destruido. Volando bajo en turbulencia, sin ascendencia, el piloto inició un viraje a la derecha que pronto se cerró en espiral descendente; un testigo la siguió hasta bajo el horizonte. Una ráfaga del noreste (viento de cola que quitó sustentación cerca de los árboles) y el centrado trasero probablemente la desencadenaron. La autopsia reveló fuerte apoyo en el pedal izquierdo contra la rotación, sin altura para recuperarse. La pérdida de control quedó de causa indeterminada.
- Local soaring flight: After an aerotow launch from Courtelary and release near Tramelan, the pilot continued a local soaring flight in turbulent bise conditions in the St-Imier valley area.
- Turbulent bise winds: A bise wind regime over the Jura created locally turbulent and gusty conditions with abrupt changes in wind intensity near the terrain.
- Aft CG limit: The glider’s mass was within limits but the center of gravity was at the aft limit, making the aircraft more sensitive in pitch and potentially in stall and spin behavior.
- Low-altitude turn in sink: Unable to find sufficient lift and flying low in the St-Imier valley, the pilot initiated a right turn, likely to interrupt the flight, at a height where margins were limited.
- Uncontrolled spiral: A witness saw the glider suddenly roll until banked with its full wingspan visible, then enter a tight, descending turn, consistent with an inadvertent spiral or spin entry.
- Rudder input applied: Autopsy evidence of a hard left rudder pedal input indicates the pilot attempted to counter the rotation, but had insufficient height to complete a recovery.
- Crash - fatal: Still in a rotating descent, the glider struck treetops, inverted, and impacted the bottom of a wooded ravine, destroying the aircraft and fatally injuring the pilot.