What happened
On October 23, 2010, a VSO 10 glider, registration OM-5607, was participating in the "Wave Camp 2010" international soaring competition near Jeseník. During the flight, the pilot experienced significant turbulence at approximately 1,300 m AMSL while being towed by a Z 42 aircraft. During the separation process, the pilot experienced difficulty releasing the towline due to high tension, and initially miscommunicated to the tow plane that the cable had broken.
Following separation, the pilot attempted to establish contact with thermal lift but was unable to gain sufficient altitude. Unable to return to the Mikulovice airfield (LKMI), the pilot decided to perform an emergency landing at a field near Bukovice. After surveying the landing area, the pilot began the final approach. During the maneuver, the aircraft encountered turbulence while flying at a low altitude near the edge of the field. The left wing struck 22 kV overhead power lines, causing the glider to lose speed and impact the ground, where it overturned on its back.
The investigation
The ÚZPLN investigation examined the flight data from the onboard GNSS recorder and analyzed the aircraft's condition. The investigation established that the pilot had performed a survey of the landing area and had calculated a landing budget that included flying low over the power lines. The investigation also reviewed the meteorological conditions, noting that mechanical turbulence was present in the area due to the terrain and local structures.
Findings
- The pilot was qualified and experienced, and the VSO 10 was airworthy.
- The pilot had sufficient altitude to reach the primary airfield but chose the emergency field due to the inability to find lift.
- The pilot's landing calculations and approach maneuver involved flying at a low altitude directly over the electrical infrastructure.
- Turbulence during the final approach caused the aircraft to bank unexpectedly, leading to the wing strike.
- The impact with the power lines caused significant structural damage, including the detachment of part of the left wing and electrical discharge marks on the wing surface.