Background
On the day of the accident, a pilot undertaking training toward a Grade 2 Agricultural Pilot Rating began work at approximately 0625 hours. The pilot and his instructor, who was flying a separate topdressing aircraft, initially flew to a block of land southeast of Rotorua, where the pilot completed 15 sowing runs while the instructor worked nearby. After a break, they transited to Waikite Valley, arriving at about 0945 hours.
Sequence of Events
After refuelling at 1045 hours, the pilot commenced sowing a “special mix” fertiliser in alternating patterns with the instructor, allowing the instructor to observe takeoffs and landings while maintaining operational efficiency. They stopped for lunch after an hour, refuelled once more, and continued. The fertiliser load was progressively increased from 900 kg to 1100 kg in 50 kg increments, with the last five loads each weighing 1100 kg. Nothing unusual was noted except the pilot aborted one landing attempt due to wake turbulence from the instructor’s aircraft during takeoff.
At the time of the accident, the pilot was performing “clearing runs” on remaining areas. Shortly before the accident, the pilot radioed the instructor to ask his location. The instructor replied, “directly behind you on the other side of the woolshed.” As the instructor approached to land, he observed the pilot’s aircraft flying westward at approximately 400 ft AGL. He then saw the aircraft make a slight left turn and begin to climb; the instructor described it as: “he started to climb and turn slightly to the left, then the plane was in a left hand spin.” The instructor believed the aircraft spun one and a half rotations left before being obscured by a ridge adjacent to the airstrip. The accident occurred in daylight at approximately 1315 hours at Waikite Valley, Rotorua, elevation 1460 ft (coordinates S 38° 18.5', E 176° 17.42').
Probable Cause
According to the official conclusions, the pilot was appropriately licensed and held a valid medical certificate; the aircraft was properly maintained with no technical discrepancies found. It is likely that during a climbing turn, the pilot inadvertently allowed an aerodynamic stall to occur, at which point the aircraft suddenly departed controlled flight. No emergency jettison of the hopper contents was attempted, and the height above ground was insufficient for a successful recovery once the departure from controlled flight had fully developed. The pilot’s lack of experience with agricultural operations and relative unfamiliarity with the aircraft type could not be eliminated as having a bearing on the accident.