What happened
On May 24, 2014, at 06:36 UTC, an L-13 Blaník glider, registration OK-8802, was involved in an accident at the Frýdlant nad Ostravicí airfield (LKFR). The flight was a training session involving a flight instructor and a student pilot, performing a circuit following a winch launch.
During the approach phase, the instructor took control of the aircraft after the student had deployed the flaps. The instructor, feeling that the aircraft's descent rate was insufficient despite the airspeed indicator showing 80 km/h, decided to execute a short landing slip at an altitude of approximately 30 to 40 meters AGL to increase the rate of descent. After applying the right rudder to initiate the slip, the aircraft drifted with the wind and transitioned into a slip via aileron input.
As the instructor attempted to recover from the slip, he noted that the controls felt soft and unresponsive. He delayed the recovery in an attempt to allow the glider to regain speed. Consequently, the aircraft touched down with a high vertical descent rate in a significant sideslip. The left wheel made side contact with the ground, causing the aircraft to skid laterally for several meters, during which the left wing struck the runway surface.
The investigation
The ÚZPLN investigation examined the flight sequence, the aircraft's maintenance history, and the pilot's actions. The investigation confirmed that the crew was qualified and the aircraft had a valid airworthiness certificate. The inspection of the aircraft following the accident revealed significant structural damage, including deformation of the left wing skin, a broken left aileron control, and a broken spar flange at a specific junction. The investigation also reviewed the technical procedures for performing slips as outlined in the L-13 flight manual.
Findings
- The instructor took control during the approach and decided to perform a landing slip to increase the descent steepness.
- The pilot waited for the aircraft to regain speed before attempting to level the wings.
- The recovery from the slip was likely not performed in a timely or coordinated manner.
- The aircraft landed with a high vertical descent rate in a significant sideslip, leading to the wing strike.
- There were no injuries to the crew.