Pérdida de sustentación del Ka 4 Rhönlerche II tras fallo en el lanzamiento por torno en aeródromo militar suizo

El 21 de marzo de 1964, un Alexander Schleicher Ka 4 Rhönlerche II experimentó un fallo en el lanzamiento por torno en un aeródromo militar en Suiza. El planeador, pilotado por un instructor de vuelo y un estudiante, sufrió una rotura de cable durante el ascenso. A pesar de la disponibilidad de una pista larga por delante, el instructor intentó girar de regreso al punto de inicio. El planeador entró en pérdida y giró desde aproximadamente 15-20 metros, impactando la pista. Ambos ocupantes resultaron ilesos, pero la aeronave sufrió daños en el ala izquierda y el morro.

1. Winch launch climb: During a dual-instruction winch launch from a military airfield, the Rhönlerche began its initial climb with the student in front and the instructor in the rear seat.
2. Cable break in climb: After the glider had covered about 200–300 m and reached roughly 50–60 m height, the winch cable’s weak link failed and the cable broke.
3. Adequate landing area ahead: Despite approximately 800 m of hard-surface runway and a further 1000 m of flat grass available straight ahead, the crew did not plan for a straight-ahead landing after the cable break.
4. Student recovers, proposes turn: The student correctly lowered the nose to stabilize the glider after the cable break and then proposed a turn back toward the launch point, which the instructor accepted.
5. Instructor steepens low turn: When the student initiated a left turn that seemed too shallow, the instructor took over and increased the bank angle without increasing airspeed at low altitude.
6. Stall and wing drop: After about 100–120° of heading change, the glider became too slow and stalled, dropping over the left wing from an estimated 15–20 m height.
7. Crash - no injury: The glider struck the hard runway first with the left wingtip and then the nose, sustaining damage to the left wing and forward fuselage, while both occupants remained uninjured.