What happened
On July 17, 2010, a Z-37A aircraft, registration OK-FJW, operated by AIR ŠUMAVA s.r.o., crashed near Vlčkovice during an agricultural spraying mission. The pilot had arrived at the working area from LKHS earlier that morning. During the refueling process at the field, the pilot and a maintenance technician inadvertently left two full auxiliary fuel tanks attached to the wings.
Upon takeoff from the field at 03:50 UTC, the pilot realized the aircraft was significantly overweight and that the auxiliary tanks were still installed. The aircraft's total weight was approximately 2163 kg, exceeding the maximum takeoff weight (MTOW) of 1850 kg by roughly 17%. Despite the heavy load and the aircraft flying at the edge of a stall during its climb, the pilot attempted to continue the mission to the target area.
While flying at an altitude of only 5 to 15 meters, the pilot encountered rising terrain and 22 kV overhead power lines. In an attempt to avoid the electrical lines, the pilot initiated a right-hand turn. During this maneuver, the aircraft lost lift and entered a descent. Although the pilot eventually performed an emergency jettison of the chemical payload, the aircraft's right wing struck a wheat field, leading to a ground impact and a subsequent roll. The aircraft was destroyed, and the pilot sustained light injuries.
The investigation
The ÚZPLN investigation focused on the sequence of events leading to the loss of control. Investigators established that the pilot was qualified and medically fit, but had been rushing during the pre-flight preparations. The investigation examined the aircraft's weight and balance, noting the significant exceedance of the MTOW. The commission also reviewed the pilot's decision-making process regarding the avoidance of obstacles and the timing of the emergency payload jettison.
Findings
- The primary cause of the accident was a loss of control during a turn while attempting to avoid an obstacle in an aircraft that was significantly exceeding its maximum takeoff weight.
- The pilot failed to remove the auxiliary fuel tanks due to haste during ground operations.
- The pilot delayed the decision to jettison the chemical payload to avoid spraying unintended areas, which prevented the aircraft from regaining sufficient altitude.
- The aircraft was operating in a near-stall condition due to the excessive weight of the fuel, chemicals, and auxiliary tanks.