What happened
On May 4, 2023, a private paramotor flight took place in Knapy, Poland. The flight, which was intended as a charity event for WOŚP, commenced at approximately 19:33. Shortly after takeoff from a local meadow, the pilot initiated a left turn. During this maneuver, the Niviuk R-BUS 4/0 entered an intensifying spiral dive.
As the aircraft descended, the pilot increased engine power in an attempt to maintain altitude and avoid obstacles. However, the aircraft continued to spiral, striking a tree and a concrete fence before crashing onto a paved road. The impact caused the engine to be torn from its frame and destroyed the front section of the carriage. The pilot, seated in the front, died at the scene. The passenger sustained serious injuries and was evacuated by helicopter to a hospital.
The investigation
The PKBWL examined the aircraft's technical condition and the flight sequence using GPS data and witness video. Investigators found that the aircraft's takeoff mass was approximately 440 kg, which was near the upper limit of the manufacturer's specified range. This high mass increased the inertia of the aircraft and the physical forces required for control.
Technical inspections of the Niviuk R-BUS 4/0 revealed that the steering system had been modified with pulleys to reduce the physical effort required by the pilot. This modification effectively reduced the control range by approximately 50%. Furthermore, the investigators found that the right trimmer was released while the left remained engaged. The trimmers were secured using a maritime cleat located behind the pilot's head, making them invisible to the pilot during flight.
Findings
- The primary cause of the deepening turn was the asymmetric setting of the trimmers, where the right trimmer had become released.
- The release of the trimmer may have been caused by the passenger unintentionally disturbing the cleat, or by increasing structural tensions during the maneuver.
- The high takeoff mass of the aircraft contributed to increased control forces and faster aircraft response to asymmetric trim.
- The modification of the steering system reduced the overall effectiveness of the pilot's ability to correct the flight path.
- The placement of the trimmer locks behind the pilot's head prevented the pilot from identifying the loss of symmetry during the 7-second window before impact.