Accident Details
The aircraft, an FU24 registered as ZK-BOA, was operated by a pilot holding a Commercial Pilot Licence who had recently completed an agricultural flying training course at Wanganui. On July 6, 1964, the pilot was conducting further practice flying to increase experience in the FU24 before commencing agricultural work. The chief pilot had briefed the pilot to load the hopper with approximately 8 hundredweight (896 pounds or 407 kg) of sand and proceed to an approved low-flying practice area. The exercise was to familiarize with the aircraft at the threshold of a stall, but not to incur a full stall, at an altitude between 1,000 and 1,500 feet.
Multiple eyewitnesses in the Mosstown area, about five miles from the airport, observed the aircraft flying low and slow. One witness, a pilot with 150 hours of experience, reported being perturbed by the height, speed, and type of flying. He estimated the height at between 150 and 200 feet during low-speed runs and turns, and noted that at times the nose would pitch down followed by an increase in engine noise. No one observed the aircraft impact the ground, but one person who had seen it flying between 100 and 200 feet heard the sound of the crash two or three minutes later.
Investigation Findings
Examination of the crash site indicated that the aircraft struck the ground in a steep diving turn to the left, leading investigators to conclude that a stall had occurred during a turn and that the impact happened while it was gaining momentum in an uncontrolled left-hand spiral. The official investigation noted that normally an FU24 would recover from such a situation if sufficient altitude were available.
The aircraft, ZK-BOA, was totally wrecked, but no fire occurred. There was no evidence of structural or engine failure prior to impact. Weather conditions were CAVU (clear and visibility unrestricted) and calm. The crash investigator determined that the aircraft stalled at about 200 feet AGL, with the left wing dropping steeply, and the aircraft struck the ground before control could be regained.
Probable Cause
The probable cause, as determined by the investigation, was that the aircraft stalled during a turn at low altitude, leading to an uncontrolled descent. The pilot's relative inexperience, both in total flying hours and in the FU24 specifically, was considered a major factor in the accident.