What happened
On August 16, 2015, an L23 Super-Blaník, registration OK-0214, was performing a winch launch training exercise at Mikulodevice Airport (LKMI). The flight was part of a training syllabus designed to teach students how to handle an emergency scenario involving an early winch motor shutdown at an altitude of approximately 50 meters AGL. During the transition from the climb to the glide phase, the winch operator intentionally cut the power at an altitude of roughly 30 meters AGL.
While the student pilot initially reacted correctly by pushing the control column forward to maintain airspeed, the aircraft lacked sufficient energy to complete the maneuver. An unexpected tailwind gust further reduced the glider's airspeed. As the student attempted to level the aircraft, the left wing lost lift and struck the ground. The impact caused the aircraft to skid 90 degrees to the left, veering off the grass runway before swinging back onto the active surface. The aircraft sustained significant damage to the left wing, landing gear, and fuselage.
The investigation
The ÚZPLN investigation examined the flight sequence, the training objectives, and the meteorological conditions. The investigation established that the winch operator had decided to terminate the tow at a lower altitude than previous flights to minimize the distance required to recover the cable. The investigators also reviewed the wind conditions, noting that a shifting wind due to an approaching shower had resulted in the takeoff being performed with a tailwind.
Findings
- The primary cause of the accident was the loss of control over the glider during the practice of a winch launch abort.
- A contributing factor was the inappropriate takeoff direction, as the flight was conducted with a tailwind, which was contrary to established training syllabus guidelines.
- The student pilot's lack of experience in managing low-altitude, low-energy flight conditions contributed to the inability to prevent the wing strike.
- The instructor, while qualified, did not take over control in time to prevent the hard landing.
- The sudden presence of a tailwind gust significantly depleted the aircraft's remaining airspeed during the critical phase of the maneuver.