What happened
On November 2, 2014, a Nimbus-2 glider, registration OK-9918, was participating in a wave soaring event near Krnov (LKKR). After being towed to an altitude of 2,114 meters, the pilot released from the towplane but was unable to establish contact with the wave formation while flying along the Hrubý Jeseník ridge.
As the pilot attempted to return to LKKR, descending cloud layers closed in, reducing visibility of the ground. Finding it impossible to reach the aerodrome, the pilot identified an available meadow near Mnichov – Vrbno pod Pradědem for an emergency landing. The pilot approached the landing area across a slope with an approximate 10-degree incline.
Upon completing the landing roll, the pilot intentionally placed a wingtip on the ground to prevent the glider from sliding further down the slope. This action caused the wing to bounce, and the force of the wind pushed the rudder, resulting in the glider rotating approximately 180 degrees. The rotation caused the tail section of the fuselage to crack and damaged the T-tail structure.
The investigation
The ÚZPLN investigation examined the flight data from the LX Colibri II instrument, meteorological reports, and the pilot's testimony. The investigation established that the pilot was fully qualified for the flight, though not instrument-rated, and had significant experience in wave soaring. Meteorological analysis confirmed that while a wave was present, the pilot could not maintain visual contact with the terrain due to the thickening cloud layer during descent. The investigation also reviewed the landing site, noting it was a designated "Red" emergency area, which carries warnings of uphill landings and potential tailwinds.
Findings
- The pilot failed to establish contact with the wave formation after release.
- Descending cloud layers forced the pilot to descend through clouds using instrument references, losing visual contact with the terrain.
- The decision to land in the field was necessitated by the inability to reach LKKR.
- The glider rotated because the pilot placed a wing on the ground to prevent sliding down the slope during a cross-slope landing.
- The aircraft sustained significant damage to the rear fuselage and T-tail due to the rotational forces.