What happened
On August 9, 2000, a training flight involving a Dutch glider crew was underway at the Rudolstadt airfield as part of a flying camp. The flight, conducted in a Schleicher ASK 21, began with a winch launch. After several previous training flights that day, the instructor and student pilot were unable to find thermal lift, leading the student to initiate a landing approach.
During the approach, the instructor assessed the aircraft's altitude as too high and took control of the glider to execute a side slip to lose altitude. Witnesses observed the side slip being initiated at an altitude of approximately 40 to 50 meters. However, the maneuver was leveled out at an extremely low altitude of only 8 to 10 meters. During the recovery, the nose of the aircraft pitched up significantly higher than normal flight attitude. The instructor noted a sharp drop in airspeed and attempted to correct the pitch by applying back pressure on the elevator, but the aircraft's momentum caused it to drop from roughly 5 meters above the ground.
The aircraft struck the ground heavily on its main landing gear while in a level attitude. Following this initial impact, the glider bounced and traveled approximately 100 meters before striking the ground a second time, leading with the nose wheel.
The investigation
The BFU investigation focused on the sequence of maneuvers performed by the instructor during the final stages of the landing approach. The investigation confirmed that the aircraft and the instructor's license were in compliance with Dutch regulations and that the instructor possessed sufficient experience and training. Investigators examined the flight path and the specific altitude at which the side slip was initiated and terminated.
Findings
- The primary cause of the accident was that the instructor induced an unrecoverable, stalled flight condition by attempting to level out of a side slip at an insufficient altitude.
- The instructor's decision to intervene to prevent a long landing resulted in a maneuver that could not be safely completed due to the proximity to the ground.
- The heavy impact resulted in two serious injuries and significant damage to the aircraft.