What happened
On July 30, 2020, a training flight was conducted at the Świebodzice (EPWC) airfield as part of a basic glider training program. The flight, involving an instructor and a student pilot, was specifically designed to practice procedures for special and emergency situations. The flight operations were conducted using a winch launch method, with departures and arrivals utilizing runway 23. Meteorological conditions on the day were characterized by light to moderate turbulence and wind speeds of approximately 3 m/s along the runway axis.
As part of the training syllabus, the instructor and winch operator had agreed to terminate the winch pull once the SZD-9 bis 1E Bocian reached an altitude of approximately 50 meters. The launch proceeded as planned, and upon reaching the target altitude, the winch operator released the tension. The student pilot successfully managed the airspeed by transitioning the glider into level flight and releasing the winch cable. However, during the release, the drogue parachute attached to the cable drifted into the right wing of the glider. The instructor took control of the aircraft and continued a straight flight path. After approximately five seconds, the parachute slid along the leading edge and separated from the aircraft, allowing the glider to land safely at the airfield.
The investigation
The PKBWL examined the sequence of events, the equipment used during the winch launch, and the meteorological conditions present during the training maneuver. The investigation confirmed that the crew held the appropriate qualifications for the flight and that the aircraft was airworthy, properly documented, and adequately insured. The investigation focused on why the drogue parachute and cable intersected with the aircraft's wing following the release of the winch tension.
Findings
- The primary cause of the incident was the excessive surface area of the drogue parachute attached to the winch cable.
- A thermal gust likely caused the parachute to inflate more rapidly and lift upward, which led to the cable and parachute striking the glider's wing.
Safety action
- The training center operator has implemented a mandatory requirement to use drogue parachutes with a diameter no greater than 1–1.2 m².