What happened
On September 13, 2020, a Pipistrel Virus SW ultralight aircraft departed from Sawin for a recreational flight to Smolnik in the Bieszczady Mountains. The flight crew consisted of the pilot and one passenger. Prior to the flight, the pilot had contacted the local mountain shelter staff to confirm that the runway was mowed and weather conditions were favorable.
Upon arrival at Smolnik, the pilot performed a low pass to assess the runway. The pilot observed that while the edges of the strip were mowed, the grass in the center was taller. Due to the proximity of a forest on the left side of the runway, the pilot decided to land closer to the right edge. Additionally, based on an assessment of the runway length, the pilot opted to touchdown near the threshold to ensure enough space for the landing roll.
During the landing roll, the aircraft encountered significant surface irregularities. These bumps caused the aircraft to deviate approximately 10 degrees to the right, eventually exiting the designated runway boundaries. In an attempt to stop the aircraft, the pilot steered onto a dirt road crossing the runway. The aircraft sustained damage to the propeller and the nose gear/fairing, but there were no injuries to the occupants.
The investigation
The PKBWL investigation examined the pilot's experience, the runway conditions, and the accuracy of available aeronautical information. The investigation established that the pilot had approximately 70 hours of experience on ultralight aircraft and that this was his first landing at the Smolnik site.
Investigators found that the actual dimensions of the runway (approximately 20 x 390 m) differed from the information available on various websites, which suggested a wider and longer strip. Furthermore, the investigation noted that the aircraft's nose gear configuration, characterized by small wheels and aerodynamic fairings, is particularly susceptible to damage when operating on uneven or tall grass surfaces.
Findings
- The primary cause of the incident was the pilot's limited experience in landing at mountain airstrips.
- Contributing factors included inaccurate and ambiguous runway dimension information available online.
- The uneven surface of the landing strip reduced the effectiveness of the aircraft's braking.
- The aircraft's landing gear design was not ideal for the uneven terrain encountered.
- The pilot's analysis of the available runway information was superficial.