What happened
On July 16, 2011, an AutoGyro MTOsport gyroplane was performing the final leg of a series of five sightseeing flights at the Breits and Breitscheid airfield. During the approach to runway 25, the aircraft was flying at an altitude of approximately 60 meters, roughly 200 meters from the runway threshold. Witnesses observed the aircraft suddenly roll to the right on its longitudinal axis, followed by a half-turn around the vertical axis, before plunging nearly vertically into the ground.
The impact occurred in a grassy area near the runway. The crash resulted in two fatalities, involving both the pilot and the passenger. The aircraft was destroyed, and minor damage was sustained to the surrounding terrain.
The investigation
The BFU investigation focused on the aerodynamic state of the aircraft during the final approach and the meteorological conditions at the time. Investigators analyzed GPS data from a Garmin unit, which revealed that the aircraft was flying at ground speeds between 90 and 108 km/h with a descent rate of 2.7 to 5.4 m/s. Notably, this approach was flown higher than the previous four landings performed that day.
Environmental factors were also examined. At the time of the accident, the wind at a nearby station was reported as 12 knots, with gusts up and to 25 knots. Local knowledge indicated that approaches to runway 25 are susceptible to turbulence and lee-side vortices caused by a nearby spruce forest. The investigation also reviewed the pilot's background, noting significant military flight experience but relatively limited experience specifically with gyrocopters.
Findings
- The primary cause of the accident was rotor unloading (undershooting), where the airflow through the rotor blades shifted from below to above the rotor plane, leading to a sudden collapse of rotor RPM and a subsequent loss of control.
- This aerodynamic failure was likely triggered by turbulence and lee-side effects from the nearby forest during a sideslip maneuver.
- The pilot was performing a sideslip (slip) to descend more rapidly, a maneuver that can be highly unstable in gyrocopters if not managed with precise pedal inputs.
- Contributing factors included strong, gusty winds that exceeded the maximum allowable crosswind component for takeoff.
- The pilot's limited experience with the specific handling characteristics and flight envelopes of gyrocopters contributed to the loss of control.
Safety action
The BFU issued a safety recommendation suggesting that the Federal Ministry of Transport, Building and Urban Development (BMVBS) establish legal frameworks to ensure that commercial passenger transport using ultralight aircraft meets safety standards comparable to those required for traditional commercial aviation.