What happened
On August 11, 2015, at Płock Aerodrome (EPPL), an SZD-50-3 Puchacz glider, registration SP-3350, was performing a simulated emergency procedure. The flight, operated by Aeroklub Ziemi Mazowieckiej, was intended to train a student pilot and an instructor on how to handle a winch release at a specific altitude.
During the maneuver, the winch operator reduced power to minimum levels at an altitude of approximately 100–150 meters. Following the reduction in tension, the pilot released the towline. However, immediately after the release, the glider began a sharp right-hand turn. The glider entered a tightening spiral dive, descending rapidly toward the ground. At a very low altitude, a small fragment of an aileron was torn away, which momentarily released the line and broke the spiral, but the aircraft struck the ground with its left wing and nose at an estimated speed of 140 km/ and resulting in two fatalities.
The investigation
The PKBWL investigation focused on the flight dynamics during the speed stabilization phase and the physical configuration of the towline end (the "pendant"). Investigators examined the construction of the pendant, which included a braking parachute and a section of line. The investigation analyzed the interaction between the trailing line and the glider's surfaces, specifically looking for evidence of entanglement. Physical traces left on the wing surface confirmed that the towline had been dragged across the right wing.
Findings
- The primary cause of the accident was the excessive nose-down pitch applied by the pilot while attempting to stabilize airspeed after the winch release. This aggressive control input caused the braking parachute and the trailing line to be thrown onto the right wing.
- The specific dimensions and construction of the pendant contributed to the accident; the large diameter of the parachute (2.2 meters) and the short length of the weighted section increased the likelihood of the line contacting the aircraft.
- The towline became lodged in the gap between the aileron and the wing, creating aerodynamic drag on the right wing that induced the fatal spiral dive.
- The aircraft was technically airworthy and all necessary documentation was in order at the time of the accident.