What happened
On July 30, 2018, a training flight was being conducted at Warsaw Babice (EPBC) involving an instructor and a student pilot in an SZD-9 bis Bocian 1E glider. The mission, coordinated with the winch operator, was designed to simulate an emergency situation involving a loss of tension and a 180-degree turn for landing.
During the maneuver, the winch operator released the tension as planned. However, due to a lack of response from the student pilot, the instructor took control of the aircraft to stabilize the airspeed and transition to a glide. During this transition, the open streamer from the towline passed over the cockpit. The end of the towline and its attachment became entangled around the canopy of the second cockpit, causing it to become stuck. Despite the instructor pulling the release handle three times, the line remained attached to the glider.
The instructor continued the landing approach while still connected to the line. During a left-hand turn, the instructor received radio confirmation that the winch operator had cut the line. Following this information, the instructor altered the landing plan and successfully landed on runway 2/8 without further incident. The crew sustained no injuries and exited the aircraft independently.
The investigation
The PKBWL examined the sequence of events, the mechanical state of the SZD-9 bis Bocian 1E, and the actions of both the flight crew and the winch operator. The investigation focused on why the release mechanism failed to function and the subsequent entanglement of the towline with the aircraft's structure. The investigation also reviewed proposed safety changes suggested by the operator, such as replacing the release mechanism and modifying winch procedures.
Findings
- The primary cause of the incident was the lack of reaction by the student pilot to the winch tension release.
- A contributing factor was the delayed release of the towline by the instructor-pilot.
- The entanglement was caused by the towline streamer passing over the cockpit, which allowed the end of the line to wrap around the second cockpit'oviewka (canopy).
- The aircraft sustained damage to the rudder (cracked plywood on the lower left side) and scratches to the fuselage and second cockpit canopy.