What happened
On August 1, 2009, a Schempp-Hirth Cirrus glider was performing a winch launch from the grass runway at the Bischofsberg glider field near Mellrichstadt, Germany. During the takeoff roll, the aircraft accelerated with such high intensity that the wing walker reported being unable to complete the standard hand signals, as the wing was pulled from her grasp.
Shortly after liftoff, witnesses observed the glider enter an extremely steep climb. At a very low altitude, the aircraft began a right-hand turn involving both pitch and roll axes. The glider eventually entered a nearly vertical dive, striking the ground with the nose and left wing. The impact destroyed the cockpit area and the fuselage, resulting in the fatal injury of the pilot.
The investigation
The BFU investigation examined the aircraft, the winch operations, and the cockpit configuration. Technical inspections of the Schem_Hirth Cirrus and the winch motor revealed no mechanical failures. The flight data recorder indicated the aircraft reached an altitude of 21 meters within five seconds of the start of the flight.
The investigation also focused on the cockpit environment. It was discovered that the pilot was using a loose Styrofoam cushion as a backrest instead of a proper seatback. Additionally, the investigation looked into the training status of the winch operator, a 15-year-old trainee, who was operating the winch without an instructor present. While the pilot had requested a "gentle" launch, the trainee relied on experience from other aircraft types to set the throttle position, which led to the high acceleration observed.
Findings
- The primary cause of the accident was the glider entering a flight regime where the airspeed fell below the stall speed due to an excessive pitch angle.
- High acceleration during the takeoff roll and inadequate cockpit seating contributed to the loss of control.
- The use of a loose Styrofoam cushion meant the pilot lacked sufficient physical support; it is believed the high acceleration pushed the pilot backward, preventing him from effectively using the elevator to counteract the aircraft's tendency to pitch up.
- The absence of an instructor during the winch operation meant there was no oversight of the trainee's use of throttle settings for a new aircraft type.