Incident avec Ka 4 Rhönlerche II lors d'un vol d'entraînement à l'aérodrome de Fricktal Schupfart

Le 6 juin 1970, un Ka 4 Rhönlerche II a connu un incident lors d'un vol d'entraînement à l'aérodrome de Fricktal Schupfart, en Suisse. Le planeur, transportant un instructeur de vol et un élève, était remorqué par un avion à moteur lorsque le câble de remorquage s'est détaché de manière inattendue à environ 50 mètres d'altitude. L'instructeur a tenté une manœuvre de demi-tour, entraînant un atterrissage non contrôlé entre un hangar et des avions stationnés. Les deux occupants sont restés indemnes, mais le planeur a subi des dommages importants. La cause du détachement du câble de remorquage n'a pas été déterminée.

1. Aerotow initial climb: During an instructional aerotow from runway 08, the Rhönlerche II with student in front and instructor in the rear climbed normally after takeoff in gusty Bise conditions.
2. Turbulence and crosswind: At about 30 m above ground the glider was hit by a gust causing a strong right bank, requiring instructor intervention after the student’s inadequate correction.
3. Student currency gap: The student’s last glider flight had been almost a year earlier, reducing recency for handling and emergency response.
4. Towline releases low: At about 50 m above ground and roughly 100 m before the runway end, the towline unexpectedly released from the glider’s nose hook for undetermined reasons.
5. Attempted turn back: Instead of landing ahead or slightly to the right on available fields, the crew initiated a right turn to attempt a downwind landing back on the airfield, with the instructor allowing or joining this maneuver after a brief wait for student reaction.
6. Low-altitude downwind turn: During the low-altitude turn into downwind over the restaurant terrace, the glider experienced a sudden height loss and drift toward the restaurant and hangar, with airspeed decaying to about 50–60 km/h.
7. Crash - no injury: The instructor attempted to land between the hangar and parked aircraft, the glider contacted the ground at the start of the hangar, slid between the hangar and two parked airplanes, and came to rest against a winch, heavily damaging the glider but leaving both occupants uninjured.