What happened
On July 10, 2005, a SZD-50-3 Puchacz glider, registration PH-1105, departed from the Lemelerveld glider airfield for a training flight. The flight was intended to assess whether the student pilot was ready to fly solo. The aircraft was being operated in a two-seat configuration with an instructor in the rear and a student in the front.
During the winch launch, the release link—a safety component designed to break under excessive load—failed at an altitude of approximately 70 to 80 meters. Following the break, the aircraft's nose was pushed down, and it initially maintained a straight flight path for about two seconds. However, a coordinated right turn was then initiated at a very low airspeed. This maneuver caused the aircraft to enter a stall, resulting in a crash into a nearby cornfield. The impact caused unrecoverable damage to the aircraft. The instructor sustained fatal injuries, while the student pilot suffered severe injuries.
The investigation
The investigation focused on the mechanical failure of the release link and the flight maneuvers following the cable break. Investigators found that a blue release link, which has a lower breaking strength intended for single-seat gliders, had been used instead of the required brown link designed for two-seat operations. This error was compounded by the fact that the combined weight of the instructor and student likely exceeded the maximum allowable weight for the aircraft, placing additional stress on the link.
While the person attaching the cable was responsible for verifying the link, the investigation noted that the instructor was also responsible for ensuring the correct link was used. Furthermore, the investigation examined the flight maneuvers, noting that standard procedures (the BOKS procedure) dictate that if a break occurs below 100 meters, the pilot should land straight ahead. In this instance, the aircraft entered a turn that led to a stall.
Findings
- The use of a blue release link with an insufficient breaking strength was the primary trigger for the accident.
- The combined weight of the occupants likely contributed to the premature failure of the release link during the winch launch.
- The pilot initiated a right-hand turn at a low altitude and low airspeed, which led to the aircraft entering a stall.
- The altitude at which the break occurred was too low to allow for the recovery of the aircraft after the improper maneuver was attempted.