What happened
On 4 December 2021, an agricultural aircraft with registration VH-ACQ was performing chemical spraying operations near Moree, New South Wales. After finishing the fifth spray run of its eleventh load, the aircraft climbed and entered a right procedure turn. During this maneuver, the aircraft descended rapidly and struck the terrain, immediately following the impact with an intense fire fueled by ruptured integral tanks.
Witnesses observed the aircraft performing a steep descent, which was consistent with an aerodynamic stall. GPS data indicated the pilot was executing a turn that involved a shallower leftward movement followed by a sharper rightward turn. The aircraft impacted the ground with a high vertical velocity and low forward speed, suggesting the pilot attempted a recovery but lacked sufficient altitude to succeed.
The investigation
Investigators examined the wreckage and flight data, finding no evidence of engine failure, control jams, or bird or tree strikes. The engine was producing power and driving the propeller at the moment of impact. The aircraft was within its approved maximum take-off weight and the center of gravity was within limits.
The investigation focused on the pilot's inputs during the turn. It was determined that the angle of attack became too high because the elevator control stick was moved too far aft while the bank angle was increased. While the pilot had previously demonstrated the ability to avoid this error in training, the specific conditions of this flight led to the loss of control.
Findings
- The pilot attempted to tighten the turn to avoid missing the target crop, placing the aircraft too close to the boundary.
- An aerodynamic stall occurred due to excessive aft elevator input during an increased bank angle.
- Environmental factors, including gusty south-westerly winds, pushed the aircraft closer to the crop area.
- The pilot was likely subject to high workload and fatigue resulting from long duty times and the complexity of the task.
- The lack of a crash-resistant fuel system contributed to the post-impact fire, which caused the one fatality.