What happened
On May 25, 2019, an Aeropro Spol/Eurofox ultralight aircraft departed from Bonn-Hangelar and proceeded to the Elz landing field. During the initial climb phase following takeoff from Elz, the aircraft entered an uncontrolled flight state. Witnesses observed the aircraft drifting slightly to the left of the departure centerline while experiencing a light crosswind from the right. As the aircraft climbed, the angle of attack increased significantly. At an altitude of approximately 50 to 60 meters, the aircraft banked sharply over its left wing, collided with trees at the edge of the airfield, and struck the ground. The impact caused a fire in the engine compartment. Both the pilot and the passenger sustained fatal injuries.
The investigation
The BFU examined the aircraft's weight and balance, the pilot's experience, and the mechanical condition of the wreckage. The investigation found that the aircraft was significantly overloaded. The takeoff weight was calculated at 509.1 kg, which exceeded the maximum allowable takeoff mass of 472.5 kg. Furthermore, the investigation determined that the aircraft's center of gravity was well behind the aft limit. Technical examination of the wreckage showed that the flight controls were functional, and the engine components, including the spark plugs, showed no signs of malfunction. The pilot had a valid license but had relatively limited experience, having flown only about 53 hours on ultralight aircraft in the preceding 36 months, with very little experience on this specific model.
Findings
- The pilot attempted to gain altitude rapidly to clear the tree line, which led to an excessive angle of attack and a subsequent aerodynamic stall.
- The aircraft was operating outside of its permitted weight and balance limits, with a center of gravity positioned significantly behind the allowable aft limit.
- A light leeward effect caused by the trees likely contributed to the loss of control during the climb.
- The high payload, consisting of the pilot and passenger, pushed the aircraft beyond its operational boundaries.