What happened
On September 3, 2016, at the Aukrug glider airfield, a Sportflugzeugbau Jubi GmbH AS-K 13 was performing a winch launch. During the climb, at an altitude of approximately 30 to 65 meters, the flight instructor intentionally released the winch cable to simulate a cable break.
Following the release, the aircraft lost airspeed and entered a steep descent. The instructor attempted to initiate a recovery maneuver, but the glider struck the ground with a high vertical velocity. The aircraft slid approximately 40 meters across the grass before colliding with a fence and bushes. The flight instructor and the student sustained serious injuries, including spinal fractures.
The investigation
The BFU investigation examined the flight sequence, the training status of the occupants, and the nature of the maneuver. The instructor had planned an unannounced drill, intending to test the student's ability to handle a cable break and perform a straight-in landing. While the instructor had briefed the student on the procedures for cable breaks prior to the flight, the specific intention for this unannounced maneuver was not communicated during the takeoff phase.
The student reported being startled by the sound of the cable release at a very low altitude, which led to a state of temporary paralysis, preventing them from following the instructor's subsequent commands, such as extending the airbrakes.
Findings
- The primary cause of the accident was the execution of a high-risk training maneuver at an insufficient altitude.
- The instructor performed the cable break simulation at an altitude of less than 100 meters, leaving a very low safety margin for error.
- The student's reaction was delayed due to the suddenness of the unannounced maneuver and the low altitude.
- The training maneuver was conducted with high realism but lacked the necessary safety reserve required for such a high-risk scenario.