What happened
On July 6, 2011, a VT 116 Orlik II glider, registration OK-8429, was conducting a flight in the vicinity of Mladá Boleslav. During the flight, the pilot attempted to locate thermal updrafts to maintain altitude. However, the pilot encountered strong sinking air, measuring approximately -4 m/s, which prevented the aircraft from reaching a safe altitude to glide back to the aerodrome at Mladá Boleslav (LKMB).
As the aircraft descended to approximately 300 m AGL, the pilot identified a potential landing site near Dalešice. While the area initially appeared to be a suitable meadow, upon closer inspection, the pilot realized the site was a field of tall wheat. Due to the lack of other suitable landing options in the rugged terrain and the need to avoid power lines located near the Jizera river valley, the pilot proceeded with the landing.
To clear trees at the edge of the field, the pilot maintained a higher airspeed and applied full brakes just before touchdown. As the glider decelerated through the tall crop, the intense resistance exerted on the low-hanging horizontal stabilizer caused the rear section of the fuselage to detach from the tail cone.
The investigation
The ÚZPLN investigation examined the pilot's flight path, the meteorological conditions, and the structural failure of the aircraft. The investigation established that the pilot was fully qualified and medically fit, and that the aircraft was airworthy with a valid inspection record. The commission analyzed the sequence of events leading from the loss of lift to the structural separation of the tail unit.
Findings
- The pilot misjudged the availability of thermal updrafts and entered a strong area of sinking air while searching for lift.
- The loss of altitude left the pilot with insufficient energy to reach the home aerodrome, necessitating an emergency landing in the terrain.
- The pilot was forced to select a field of tall wheat as the only viable landing option.
- The physical resistance of the tall wheat against the low-positioned horizontal stabilizer caused the detachment of the tail section.
- There were no injuries to the pilot or any third parties.