What happened
On the evening of August 7, 2009, a pilot was conducting a second sightseeing flight in an AutoGyro MTOsport gyrocopter. After completing an initial flight from Northeim airfield, the pilot departed again at 19:32 with a passenger. The aircraft flew south, passing the Plesse Castle ruins at a low altitude.
While performing a left-hand turn toward rising terrain, the aircraft collided with the highest tree on a wooded ridge east of the castle ruins. The impact caused the aircraft to crash into the forest at a 240-degree heading. Both the pilot and the passenger sustained fatal injuries due to the high-speed, near-vertical impact.
The investigation
The BFU examined the wreckage and analyzed GPS data from a smartphone carried on board. The investigation focused on the aircraft's technical condition, the pilot's qualifications, and the environmental conditions at the time of the accident. While witnesses reported hearing loud, irregular noises similar to breaking wood or a woodchipper, a technical examination of the engine and fuel system showed no evidence of a mechanical failure.
Investigators also noted that the aircraft had recently undergone a conversion to the MTOsport model and had been issued a new airworthiness certificate just one day prior to the accident. Although impurities were later found in the carburetor float chambers of the engine, the BFU determined there was no evidence that a fuel system malfunction caused this specific accident.
Findings
Several contributing factors led to the collision with the trees:
- The aircraft was overloaded by approximately 54 kg, which likely degraded the expected flight performance.
- The high density altitude, caused by a temperature of 28°C, reduced the maximum engine power.
- The pilot was executing a tight turn toward rising terrain at a low altitude and low airspeed, which required increased power to maintain altitude.
- The low position of the evening sun may have caused visual impairment for the pilot during the final phase of the flight.
Ultimately, the combination of the high gross weight and the reduced engine performance prevented the aircraft from gaining sufficient altitude to clear the obstacle during the maneuver.