What happened
Following a period of poor weather caused by a weakening frontal system, a topdressing flight resumed operations. As mist and low cloud had dissipated and winds had increased, the pilot began a sixth pass over a narrow, rising valley. This specific run followed an increase in the aircraft's payload.
During the maneuver, the pilot encountered initial lift followed by significant sinking air. While attempting to navigate the narrow terrain, the pilot was unable to reverse the flight path. Despite applying full power, deploying 20 degrees of flaps, and attempting to dump the payload, the aircraft failed to maintain a climb. The aircraft subsequently stalled during a left-hand turn and collided with the side of the valley.
Upon impact, the left wing struck the terrain first, which resulted in the loss of the outer wing section. The aircraft then hit the ground in a flat position while rotating anti-clockwise, eventually skidding to a stop tail-first. The impact caused the hopper mouth to be torn loose; this component, along with the nose landing gear, breached the cockpit floor. This structural failure trapped the pilot's legs, causing serious injuries. Although the pilot experienced post-impact disorientation, the use of a protective helmet and a full restraint harness prevented further trauma, and no fire occurred following the crash.
Findings
- The pilot encountered heavy sinking air while operating in a narrow valley.
- The aircraft stalled during a turn due to an inability to establish a climb despite maximum power and flap settings.