What happened
On July 16, 2011, a Diamond DA42, registration HB-LUL, departed from St. Gallen-Allevrhein airport for a flight initially heading west toward Lausanne. The flight path subsequently took the aircraft over the Gruyères region, the Haslital, and the Susten Pass, eventually moving toward eastern Switzerland and the Schaffhausen area.
At approximately 15:55 local time, the aircraft struck the eastern facade of a single-family residence located on Wiesengrundstrasse in Oberhallau. The impact caused an explosion, and both the aircraft and the building were destroyed by fire. The pilot, who was the sole occupant of the aircraft, sustained fatal injuries. A resident of the house was rescued from the building without injury.
The investigation
The investigation was conducted by the Swiss Transportation Safety Investigation Board (SUST). While the event involved an unlawful interference with aviation, the SUST performed a technical-scientific assessment to determine if any flight safety improvements could be identified. The investigation included a review of the flight path, the circumstances of the impact, and the findings from criminal authorities.
Findings
Evidence recovered from the pilot's residence, including a suicide note, led investigators to conclude that the pilot intentionally caused the collision. Following the conclusion of criminal proceedings by the relevant authorities and the determination that no further flight safety improvements could be derived from the event, the investigation was closed.