What happened
On September 1, 2019, a PZL-Koliber 150, registration SP-KYS, departed from EPOM airport for a scheduled flight training mission. The flight, intended to cover a route between EPOM, Turek, Uniejów, and the Warta river, initially proceeded as planned. However, after passing Uniejów, the crew deviated from the flight plan, choosing to fly along the Warta riverbed instead of the designated path.
During this unauthorized segment, the crew descended to altitudes as low as 20–30 m AGL to perform a simulated field landing exercise. At approximately 11:45 LMT, while flying at roughly 14 m AGL near the Jeziorsko dam, the aircraft struck a set of parallel power lines. The impact caused significant structural damage to the aircraft, including the destruction of the vertical stabilizer and the loss of the rudder. Despite the collision, the engine continued to operate, and the crew successfully navigated under a second, higher power line. After assessing the aircraft's stability and control, the crew returned to their original flight plan and landed safely at EPOM at 12:10 LMT. There were no injuries to the crew.
The investigation
The PKBWL investigation examined the flight logs from the Sky Demon navigation software, which revealed that the crew had significantly altered both their route and altitude. Investigators also inspected the aircraft's extensive damage, which included a broken vertical stabilizer spar, deformed fuselage frames, and damaged cockpit glazing. The investigation included a drone survey of the accident site, which showed that the power line pylons were painted a greenish-gray color and partially obscured by tall trees, making them extremely difficult to detect from a low altitude.
Findings
- The primary cause of the accident was the descent to an unsafely low altitude in close proximity to terrain obstacles.
- The crew changed the planned flight route during the mission.
- The crew was unaware of the location of power line obstacles on the newly chosen route.
- The visual identification of the power lines was severely hindered by the color of the pylons and surrounding vegetation.