What happened
On May 30, 2023, a pilot participating in a gliding competition in the 18-meter class was completing a 471 km cross-country flight. While approaching the target airfield in Bayreuth, the pilot was managing a sequence of arrivals following a group of other aircraft.
During the approach to runway 06, the pilot noted significant lee-side effects. To maintain spacing and avoid the other aircraft in the pattern, the pilot retracted the airbrake and adjusted the wing camber to level 4 to maximize glide performance. As the pilot progressed on the final approach, he realized the aircraft was losing altitude too rapidly. Although he briefly considered diverting to a valley to restart the engine, he chose to continue the approach at a speed of approximately 120–130 km/h.
During the final phase, the aircraft encountered massive lee-side turbulence, causing it to descend below the airfield elevation. The Alexander Schleicher ASH 31 Mi struck trees and bushes located just below the airfield level, approximately 100 meters from the threshold of runway S1, before impacting the ground. The impact caused the aircraft to rotate, ultimately coming to rest upside down with the cockpit facing downward.
The investigation
The BFU examined GPS data from the aircraft's LX 9000 navigation system, which allowed investigators to reconstruct the flight path. The investigation also reviewed witness video footage that captured the final five seconds of the flight, confirming the aircraft's descent below the airfield height.
Investigators also reviewed meteorological data and airfield communications. The wind at the time of the accident was reported as 17 knots from 030°, with gusts reaching 24 knots. While the daily briefing had noted the potential for lee-side effects on runway 06, the investigation focused on the aircraft's interaction with these conditions during the final approach.
Findings
- The pilot was flying an Alexander Schlelauncher ASH 31 Mi motor glider.
- The pilot sustained a stable fracture in the lumbar spine.
- The aircraft sustained heavy damage, including a crushed nose, a broken instrument panel, and a shattered canopy.
- The primary cause of the accident was the aircraft encountering severe lee-side turbulence during the final approach, which led to a loss of altitude below the terrain level.