What happened
On June 10, 2010, at 09:09 UTC, a Z-37A agricultural aircraft, registration OK-OJS, was performing aerial spraying operations from a working area in Polánka, Czech Republic. The aircraft was carrying approximately 530 kg of chemical granules and was operating at its maximum takeoff weight (MTOW).
During the takeoff roll, the aircraft failed to accelerate to a safe climb speed. While the engine was operating normally at takeoff power, the aircraft remained at an altitude of only 1.5 to 3 meters above the ground, traveling at approximately 80 km/h, significantly lower than the typical 110–120 km/h achieved in previous flights.
To avoid 22 kV overhead power lines located at the end of the takeoff area, the pilot attempted a right-hand turn with a 15-degree bank. Due to the low altitude and the immediate need to avoid the lines, the pilot did not have sufficient time to perform an emergency discharge of the chemical payload to lighten the aircraft. During this maneuver, the aircraft entered a stall, causing the landing gear to strike the ground. The aircraft subsequently struck bushes at the edge of the field, causing the aircraft to rotate and crash into a nearby grain field, where it was destroyed.
The investigation
The ÚZPLN investigation established that the pilot was fully qualified, medically fit, and highly experienced in agricultural flight operations. The aircraft was airworthy and had no recorded mechanical failures during the flight. The investigation focused on the aircraft's performance under specific environmental and loading conditions, noting that the aircraft was at its MTOW and operating in high ambient temperatures (30°C), which can affect engine and aerodynamic performance.
Findings
- The aircraft was operating at its maximum takeoff weight.
- High ambient temperatures and the potential for thermal turbulence over the heated field reduced the aircraft's overall flight performance.
- The aircraft failed to reach the required safe takeoff speed after liftoff.
- The pilot's attempt to maneuver around overhead power lines, combined with the low airspeed and high weight, led to an aerodynamic stall.