What happened
On August 28, 2011, at approximately 13:43 UTC, a mid-air collision occurred near runway 08 of the Zell am See aerodrome in Austria. The accident involved two aircraft: a Diamond HK 36R "Super Dimona" motor glider and a Cessna 150F.
The HK 36R had departed from Paterzell for a private VFR flight. Flight data recorder information indicates the aircraft performed a continuous descent from approximately 2,335 meters to 1,330 meters before initiating a final approach to runway 08 at an average speed of 65 knots. Simultaneously, the Cessna 150F was also on approach to the same runway.
At an altitude of roughly 30 to 50 meters above the ground, the two aircraft collided approximately 360 meters before the runway threshold. Following the impact, both aircraft plummeted into a meadow adjacent to the aerodrome. Emergency responders had to use specialized cutting equipment to extricate the occupants from the wreckage. The collision resulted in four fatalities: the pilot and passenger of the Cessna 150F, the passenger of the HK 36R, and the pilot of the HK 36R, who later succumbed to his injuries at a hospital.
The investigation
The SUB investigation reconstructed the flight paths using eyewitness accounts, wreckage analysis, and flight data from the HK 36R. The investigation examined the flight profiles of both aircraft, the cockpit environments, and the physical impact marks on the airframes. Investigators also performed toxicological analysis on the occupants and reviewed the visibility limitations inherent in the aircraft designs, specifically the view obstructions caused by the low-wing configuration of the Cessna 150F relative to the high-wing HK 36R.