What happened
On June 22, 2013, at 13:04 UTC, an L-33 Solo glider, registration OK-742 and 27, experienced a hard landing at the Plzeň-Letkov airport (LKPL). The pilot, who was performing solo training flights after several instructional sessions earlier that day, was executing a circuit with a landing into a restricted area.
After completing the fourth circuit turn at a speed of approximately 100–105 km/h, the pilot fully extended the airbrakes for the final approach to runway 26. During the flare maneuver, the aircraft struck the ground with significant force at an altitude of approximately 2 meters AGL. The impact resulted in structural damage to the metal tail cone where it transitions to the vertical stabilizer, wrinkling of the upper wing center section skin, and minor damage to the wingtips. No injuries were reported, and the pilot was not under the influence of alcohol.
The investigation
The ÚZPLN examined the flight sequence, the aircraft's maintenance history, and the pilot's actions. The investigation established that the aircraft had a valid airworthiness certificate, with its last annual inspection completed in August 2012. The pilot held a valid Class 2 medical certificate and had a total flight time of 214 hours and 48 minutes on various gliders.
The investigation focused on the pilot's management of the airbrakes during the final stages of the approach. The flight manual for the L-33 Solo specifies that airbrakes should be opened gradually due to their high effectiveness. The investigation analyzed whether the pilot's handling of these surfaces contributed to the loss of airspeed and subsequent descent rate.
Findings
- The pilot misjudged the height of the flare.
- Improper manipulation of the airbrakes led to a sudden loss of airspeed during the flare phase.
- The sudden loss of airspeed caused the glider to sink abruptly, resulting in the hard impact.
- All structural damage to the L-33 Solo was a direct result of the impact with the ground.