What happened
On September 20, 2019, during a flight examination at the Gdynia Chwarzno-Wiczlino model airfield, an accident occurred involving a T-34 unmanned aircraft (registration SP-YRBA). The flight was part of a practical exam intended to upgrade the operator's qualifications for BVLOS (Beyond Visual Line of Sight) operations in the multi-rotor category.
Prior to the incident, a different T-34 unit (SP-YRBB) had been used for an earlier flight but was taken out of service due to a propeller failure. The operator then prepared the SP-YRBA for flight. During the pre-flight phase, the operator moved the aircraft a few meters to avoid tall grass. Following this movement, the operator proceeded to arm the aircraft.
As the operator pressed the safety switch to arm the motors, the aircraft unexpectedly engaged its engines and performed a sudden, forceful takeoff. The operator, who was leaning over the aircraft, was struck by the drone, resulting in facial injuries that required 29 days of medical leave. The aircraft sustained minor damage.
The investigation
The PKBWL investigation examined the flight logs, the aircraft's manual, and witness statements from the examiner and instructors. The investigation focused on the arming procedure and the physical setup of the operator during the pre-flight sequence. Investigators also reviewed the technical instructions provided for the T-34 model and the regulatory compliance of the aircraft used during the examination.
Findings
- The operator failed to follow the specific safety protocol required by the manufacturer's manual, which mandates holding the aircraft's centerplate to prevent it from lifting during the arming process.
- The manufacturer's instructions for the T-34 were found to be contributing to the error; the manual requires the operator to wear the controller on a neck strap, which places the equipment directly above the aircraft, obstructing the view and making it difficult to hold the centerplate and the safety switch simultaneously.
- There was insufficient oversight by the examiner, who did not intervene when the operator performed the arming procedure incorrectly.
- The aircraft used for the exam, SP-YRBA, was not entered into the official aircraft register, which is a requirement for BVLOS operations.
- The manual contained imprecise descriptions regarding control modes, specifically misidentifying the function of the left stick in Mode 2 for multi-rotor electric propulsion.