Blanik L-13 Absturz während Kunstflugtraining auf dem Flugplatz Schaffhausen mit Todesopfern

Am 18. September 1976 war ein LET L-13 Blanik in einen tödlichen Unfall auf dem Flugplatz Schaffhausen in der Schweiz verwickelt. Das Segelflugzeug, gesteuert von einem Fluglehrer und einem Kunstflugschüler, verlor während eines Trainingsflugs die Kontrolle. Zeugen berichteten von einer Reihe von Kunstflugmanövern, gefolgt von einem steilen Spiralabstieg. Die Untersuchung bestätigte einen mechanischen Ausfall der Steuerverbindung des rechten Querruders, der zum Kontrollverlust beitrug. Beide Insassen kamen ums Leben, und das Flugzeug wurde beim Aufprall zerstört.

1. Aerotow aerobatics flight: The instructor and aerobatic student departed Schaffhausen on aerotow for an aerobatic training flight and released near the airfield at about 1000 m above ground.
2. Failed vertical manoeuvre: After several renversements, the pilot pulled the Blanik up to the vertical at about 500 m above ground, where it stopped, slid backwards 50–100 m, and then violently tumbled about the lateral axis.
3. Aileron linkage failure: Around the time the glider returned to normal attitude, witnesses heard a loud bang later determined to be the right aileron control linkage failing, leaving the right aileron inoperative.
4. High control loads: The extreme attitudes and airflow reversal during the botched vertical manoeuvre likely imposed unusually high loads on the flexible aileron control system, contributing to the fracture of the aileron linkage.
5. Attempted recovery actions: After the bang the glider flew straight for about two seconds with flaps and airbrakes partially extended, indicating the crew attempted to regain control and possibly configure for recovery or descent.
6. Uncontrolled right spiral: With the right aileron disabled, the glider entered an increasingly steep, irregular right spiral from about 300 m above ground, with turn rate and speed increasing despite control inputs.
7. Crash - fatal: After 4–5 turns in the steepening right spiral, the glider struck the ground with high speed and about 75–80° right bank, killing both occupants and destroying the aircraft.