Blanik L-13 Zwischenfall in Cortebert: Strömungsabriss in niedriger Höhe während des Schleppausklinkens
Am 25. Juni 1989 erlebte ein LET L-13 Blanik in der Nähe von Cortebert, Schweiz, einen Strömungsabriss in niedriger Höhe während eines Flugzeugschlepps. Die Luftbremsen des Segelflugzeugs wurden kurz nach dem Start versehentlich aktiviert, was vom Piloten aufgrund von Funkproblemen nicht bemerkt wurde. Der Schlepppilot klinkte das Segelflugzeug aus, um Hindernissen auszuweichen, was zu einer Rechtskurve und anschließendem Strömungsabriss führte. Der Passagier wurde schwer verletzt, während der Pilot unverletzt blieb. Das Segelflugzeug wurde beim Aufprall zerstört.
- Aerotow takeoff: During an aerotow departure from Courtelary, the Blanik began its initial climb behind the Robin towplane.
- Airbrakes not locked: Because the pre-takeoff check of the airbrake locking was incomplete, the glider launched with the airbrakes not properly locked, leading to their inadvertent deployment shortly after liftoff.
- Low front seat weight: The load on the front seat, including passenger and parachute, was about 8 kg below the prescribed minimum, adversely affecting handling at low speed.
- Radio warnings missed: Multiple urgent radio calls from the tow pilot and ground personnel about the extended airbrakes were not recognized by the glider pilot due to a congested frequency and his focus on the poor climb.
- Towplane releases glider: Approaching Cortebert with obstacles ahead and unable to climb adequately with the glider’s airbrakes extended, the tow pilot performed an emergency release of the glider.
- Low-altitude turn stall: After release, the glider pilot initiated a right 180-degree turn at low height, during which airspeed decayed rapidly and the glider stalled instead of landing straight ahead in available fields.
- Crash - serious injury: The stalled glider descended into a field near Cortebert, seriously injuring the front-seat passenger, leaving the pilot uninjured, and destroying the aircraft.