What happened
On July 23, 2019, a pilot was conducting a local flight near the Moravská Třebová airfield (LKMK) in a L 13A Blaník, registration OK-2708. After approximately one hour of soaring in thermal currents, the pilot decided to terminate the flight and perform a landing on runway 26.
During the third and fourth legs of the landing pattern, the aircraft encountered a severe gust of turbulence. This sudden impact caused the pilot to momentarily lose concentration. While attempting to manage the approach, the glider drifted off the runway centerline and impacted a field of tall corn approximately 40 meters from the edge of the airfield. The aircraft sustained extensive damage, including the detachment of the stabilizer from the fuselage and destruction of the vertical fin. The pilot was uninjured.
The investigation
The ÚZPLN investigation examined flight data from a Flarm IGC recorder, meteorological records from the Czech Hydrometeorological Institute, and testimonies from the pilot and instructors. The analysis focused on the aircraft's flight path, the wind conditions, and the pilot's configuration of the aircraft during the critical phase of flight. Investigators also reviewed the pilot's recent flight history, noting a previous landing accident in a different glider (VSO-10) only a month prior.
Findings
- The crosswind component during the approach was approximately 8.5 m/s, which significantly exceeded the L 13A Blaník flight manual limit of 5.5 m/s.
- The pilot likely deployed the air brakes unintentionally during the approach, which increased the descent rate and contributed to the loss of control.
- Turbulence encountered during the third and fourth legs of the pattern contributed to a partial loss of pilot concentration.
- The pilot's psychological state, influenced by the lingering stress of a previous accident, was a contributing factor to the loss of focus following the turbulence.
- Despite the loss of concentration, the pilot maintained a safe airspeed above the stall speed while flying over the cornfield, which prevented a more critical wing-drop stall.