Occurrence
On 9 May 2021 at 17:12 LMT, an EV-97 Eurostar SL ultralight aircraft, registration OK-YUA98, initiated a take-off run on runway 18 at Milewo aerodrome (EPMX) for a return flight to Płock aerodrome (EPPL). The aircraft was the last of three ultralight planes that had flown to EPMX earlier. During the take-off run, still below rotation speed, the aircraft encountered a large water puddle covering approximately one-third of the runway from the threshold. The puddle softened the surface. Upon entering the puddle, the aircraft experienced aquaplaning, losing directional control. It began to turn left toward a pond and adjacent buildings. The pilot did not abort the take-off. Rudder input was applied only nine seconds after the start of the take-off run, and subsequent control inputs relied on ailerons, which were ineffective. The aircraft continued accelerating at full take-off power. It bypassed the pond, and the right-wing tip struck the terrace balustrade of a building, while the wing torsion box hit a vertical roof support beam. The aircraft then performed a full vertical rotation and came to rest against a fence, damaging it. The engine stopped, and no fire occurred.
Injuries to Persons
The pilot and a bystander standing on the terrace of the building that was struck did not suffer any injuries.
Damage to Aircraft
The aircraft was substantially damaged. The right wing and its mounting, the propeller, the fuselage structure, horizontal stabilizer, elevator, and landing gear were seriously damaged. The engine was qualified for a maintenance check.
Meteorological Information
The weather was daylight, visual meteorological conditions with CAVOK, a clear summer day, and light to moderate wind from the southeast. The weather had no influence on the occurrence.
Analysis
The State Commission on Aircraft Accidents Investigation (PKBWL) analyzed CCTV recordings, pilot and aerodrome operator statements, and runway characteristics. The grassy runway had longitudinal unevenness and relied on gravity for rainwater drainage, which led to the formation of the puddle. The aircraft's wheels lost adhesion due to aquaplaning, and the propeller torque caused a strong left turn. The pilot did not abort the take-off despite the significant trajectory disturbance. The power control knob was reported by the pilot as stuck in the full position; the knob's design includes a brake mechanism that can impede rapid power reduction when overtightened. The investigation concluded that the loss of directional control and subsequent collision resulted from the combination of aquaplaning on the water-covered runway and the pilot's delayed and ineffective corrective actions.