Covering form of preliminary or final report
| Date of event : | 2022-07-31 |
| Incident number : | CZ-22-0792 |
| Report : | Final report |
| Place of event : | near Vlastislav village |
| Registration mark : | Accident |
| Weight category MTOM: : | <2250 kg |
| Type of operation : | Recreational and sport aviation |
| Plane / SFM : | Gliders |
| Type of plane / SFM : | Ventus C |
| Health effects of event : | Without injury |
| PDF document : | 
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Description:
SUMMARY
Overview
On 31 July 2022, the AAII was notified of an air accident of the Ventus C glider. After forced field landing due to failure to find a suitable thermal lift, the glider touched down and rotated during landing run. Due to the impact of forces in rotation, the rear part of the fuselage was damaged. The pilot was not hurt.
Factual Information
It was a competition flight during the Ransky Cup 2022. There was a common briefing for all competitors. The preparation for flight and of the glider was standard. The take-off was carried out by aerotow. A racing high-speed flight followed, according to the declaration, at a distance of 339.5 km with three turning points. After the first two turning points were passed, weather and thermal conditions deteriorated at the third leg in the area of Litoměřice. It was almost cloudy in combination with fresh western with. The pilot decided to resolve the decreasing altitude at the northern declared leg on a sunny windward slope near the village of Vlastislav where he was trying to make use of a thermal lift. Because the wind was increasing in strength, he failed to do so, and therefore after a few minutes spent at the altitude of 250–300 m above the ground, he decided to land into the terrain in a freshly cut stubble field. He had already pre-selected the field while he was circling. He carried out the landing manoeuvre from the base leg position. He performed approach to landing with flaps in position 2. He maintained the speed and landing calculation with regard to the turbulent environment at about 110–120 km·h-1 using brake flaps. He also observed a safe altitude above the road he was flying over. The touchdown was normal. After a straight landing run approx. 50 m long, the right half of the wing came into contact with a slightly ascending terrain and the glider then started rotating. After stopping, the pilot detected damage (breaking) of the tail part due to lateral strain caused by rotation when the right half of the wing came into contact with the ground. After stopping, the final position of the longitudinal axis of the glider formed an angle of approximately 120 degrees with the direction of the landing run. No injury or damage to third-party property occurred.
Analysis
The pilot held the necessary qualification and was medically fit for performing the given flight. He had sufficient flying experience with the aircraft type. The glider had a valid airworthiness certificate and was fit to fly.
The pilot was conducting a high-speed competition flight when he was continuously flying into thermal lifts. After approx. 3.5 hours, the thermal conditions deteriorated and the pilot failed to find any other thermal lifts with his glider and that is why he decided to land into the terrain. He inspected the area before landing. It was a low-cut stubble grain field. He was landing via the left circle, into wind, approximately in the western direction. After touch down, the right half of the wing came into contact with a slightly ascending terrain after approximately 50m landing run and the glider rotated by 120 degrees, and then stopped approximately after further 20 m. The pilot was not aware of the decline of the right half of the wing due to the impaired lateral controllability when decelerating the glider. He rather attributed the contact of the right half of the wing with the terrain to the oscillation of the wing with a span of 17.6 m during the landing run on a not perfectly even, ascending terrain. The rear part of the fuselage was damaged. The pilot was not hurt.
During the air accident, the rear part of the fuselage was damaged with transversal and longitudinal cracks and it was also broken off approx. 30 cm in front of the keel area.
Causes
The cause of the incident was a contact of the end of the right half of the wing with a slightly ascending profile of the cut grain field (low stubble) caused, most likely, by wing oscillation during landing run after the glider’s forced landing into terrain.
Attached final report in PDF file is in original Czech language.