Incident Overview
On July 2, 2016, at approximately 9:55 local time, a training flight involving a SZD 9 Bis 1E Bocian glider (registration SP-2762) was conducted at the Pobiednik Wielki airfield (EPKP) near Krakow. The glider was being launched by a winch, with a student pilot and an instructor on board. The student had logged 4 hours and 30 minutes of flight time across 58 previous flights.
Sequence of Events
Before the incident, the instructor had briefed the student after two practice landings. During the next launch, the instructor radioed the winch operator to tighten the line. The winch operator acknowledged. After the line was taut, the glider began to roll. Noting that the speed was building too slowly, the instructor instructed the winch operator to pull faster. The glider lifted off to about 0.5 meters, at which point the winch tension was completely lost. The winch line parachute deployed and approached the left wing of the glider. The instructor released the line and opened the airbrakes, but the parachute and a section of line became draped over the wing at approximately one-third of its span, causing damage to the leading edge—a hole of about 5 centimeters in diameter. The flights were terminated, and a corresponding entry was made in the glider's technical log.
Contributing Circumstances
It was later determined that the winch operator had removed his headphones, making radio communication from the glider barely audible through the winch cabin speaker. The instructor's commands, including the request for faster winching, were poorly understood.
Probable Cause
The investigation concluded that the incident resulted from the winch operator's failure to follow procedures.
Post-Incident Actions
On July 4, 2016, additional training was conducted for the winch operator covering procedures and winch operation.
Commentary from the Commission
The commission noted that the segment of the winch line between the parachute and the metal ring was approximately 12 meters long and was not protected by a garden hose sleeve. The commission opined that if that segment had been about 20 meters long and protected by a garden hose sleeve, the likelihood of glider damage would have been reduced. The sleeve stiffens and weights the end of the line, causing it to swing away from the glider after release, increasing separation, particularly for lightweight synthetic lines. Additionally, if the line did get thrown over the wing, the sleeve would reduce the risk of jamming in the gap between the aileron and the wing.