What happened
On June 17, 2000, a Grob G 109 B motor glider departed from Schweighofen for a flight to Freiburg i. Br., later continuing toward Konstanz. The aircraft was carrying two occupants. At approximately 13:40, a witness reported hearing a loud engine noise followed by a heavy impact in a forested area. A search conducted by a rescue helicopter located the wreckage in a steep valley near Kirchzarten.
The aircraft struck the terrain at the end of a steep valley with a significant lateral tilt and a heavy longitudinal pitch toward the rising slope. Both the pilot and the passenger sustained fatal injuries at the scene.
The investigation
The BFU investigation reconstructed the flight path using witness statements and wreckage analysis. The investigation was complicated by the high degree of destruction at the crash site and the difficulties encountered during the recovery of the passenger.
The pilot held a valid private pilot license with an endorsement for self-starting motor gliders, though he had relatively limited flight experience, with only 105 total hours and very few hours specifically on the Grob G 109 B. Notably, this flight was the pilot's first time operating in the Black Forest region.
Technical examination of the aircraft revealed no mechanical failures or defects that contributed to the accident. The aircraft was properly maintained and registered. While the exact takeoff weight could not be determined due to fuel leakage at the site, it was estimated to be near the maximum allowable takeoff mass. Weather conditions at the time were favorable, with clear skies and visibility exceeding 10 km.
Findings
- The pilot misjudged the distance, altitude, and speed relative to the rising terrain ahead.
- The pilot failed to initiate a turn or climb sufficiently early to clear the ridge.
- During an attempt to climb, the aircraft's airspeed dropped below the stall speed, causing the aircraft to bank sharply to the right and descend into the trees.
- The pilot's limited flight experience and lack of familiarity with the mountainous terrain contributed to the error.