What happened
On June 15, 2014, a pilot operating a Schempp-Hirth Ventus 2B glider departed from Tulln airfield (LOXT) for a cross-country flight. While flying near Herzogenburg, the pilot encountered deteriorating thermal conditions, causing the aircraft to lose altitude. After consulting with other pilots via radio, the pilot decided to divert to Völtendorf airfield (LOAD), which was geographically closer.
As the flight progressed, the aircraft continued to descend. While flying parallel to a highway, the pilot identified overhead power lines positioned across the flight path. To avoid a collision with these lines, the pilot executed a sharp 90-degree right turn. This maneuver forced an immediate decision to perform an emergency landing on a cultivated field located within a residential area.
During the low-altitude approach over the housing estate, the aircraft entered an uncontrolled stall. Due to the insufficient altitude, the pilot was unable to recover. The glider struck the ground nearly vertically with its right wing between two houses, causing significant damage to the aircraft and a residential building. The pilot sustained one minor injury.
The investigation
The Austrian Federal Safety Investigation Board (SUB) reconstructed the flight sequence using pilot statements and FLARM data. The investigation examined the aircraft's configuration, the pilot's decision-making process, and the environmental conditions. The investigators analyzed the aircraft's flight manual, maintenance records, and the pilot's flight experience and authorizations. The investigation also reviewed the pilot's use of the "decision funnel" concept regarding landing site selection and altitude management.
Findings
- The primary cause of the accident was an uncontrolled stall at a low altitude that could not be recovered due to insufficient height.
- The aircraft was not in the proper landing configuration; the landing gear was not extended, and the camber flaps remained in the "S1" high-speed setting, which increased the stall speed.
- The pilot's decision to perform an emergency landing was significantly delayed.
- There was a failure to consider several suitable alternative landing sites earlier in the flight.
- The pilot's decision-making was influenced by a misjudgment of distances and an oversight of available landing options.
- The pilot attempted to fly directly over a residential area to reach the chosen field, which left no margin for error.