What happened
On April 21, 2018, at 16:55 UTC, a Schepp-Hirth NIMBUS 2b glider, registration OK-6441, was performing a glide from its last waypoint back to Plasy Airport (LKPS). While the pilot had initially planned a long-distance thermal flight, increasing north winds near the airfield significantly reduced the glider's remaining altitude and range.
As the glider approached the village of Rybnice, the pilot realized that the remaining altitude was insufficient to reach the runway at LKPS. In an attempt to reach the airfield, the pilot utilized the descending terrain to gain speed and altitude. However, while maneuvering near the northern edge of the village, the pilot attempted to fly through a narrow gap between a line of trees and a large tree located near a residential property. During this maneuver, the right wing of the NIMBUS 2b struck the treetops at approximately 5 meters AGL. The impact caused a sudden change in the aircraft's trajectory, leading to an uncontrolled descent. The glider struck the ground with its tail, then impacted a wire fence and a wooden garden structure, finally coming to rest on its belly in a garden.
The investigation
The ÚZPLN investigation examined the flight data recorder, meteorological reports, and witness statements. Witnesses near the site reported hearing two heavy thuds and subsequently finding the heavily damaged aircraft. The pilot, an experienced instructor with over 3,000 flight hours, was uninjured but was taken to a hospital for a medical evaluation, which yielded negative results. The investigation also reviewed the aircraft's maintenance history, noting that the glider had undergone its annual inspection on April 2, 2018, and was found to be airworthy.
Findings
- The pilot failed to terminate the glide to the home airfield in a timely manner to perform a safe landing in suitable terrain.
- The pilot attempted a forced landing in close proximity to the airfield, flying at an extremely low altitude over obstacles.
- The pilot incorrectly estimated the distance to and clearance from the trees, leading to the collision with the tree canopy.
- Increasing headwinds reduced the glider's glide performance, making the original plan to reach LKPS impossible.
- The impact with the trees caused the aircraft to become uncontrollable, resulting in significant structural damage to the fuselage, wings, and tail section.