Accident Description
While turning onto the sowing run at approximately 300 feet above ground level, the aircraft encountered a significant downdraught and a loss of at least 5 knots airspeed. The pilot responded by aggressively pushing the control column forward and turning toward lower ground. At the same time, he activated the load jettison lever. The rate of load release and the aircraft's recovery from the downdraught were much slower than expected. The pilot found himself on a collision course with rocks in a paddock. He pulled back firmly on the controls, but the left wing struck the ground. The aircraft overturned and slid backward before coming to a halt.
An instructor pilot, operating a second Fletcher on the same job, witnessed the accident. He jettisoned his own load, landed nearby, and went to assist the pilot.
Meteorological Conditions
Weather conditions were favorable for topdressing, but katabatic winds were likely present in the valley following a clear, cool night. At the time of the flights, a light northwesterly wind was in place, which could have augmented the katabatic flow. Turbulence was very light. Shortly after the accident, light wind gusts were noted; a steadier, stronger down-valley wind developed by mid-morning.
Pilot Background and Response
The accident pilot had completed his training only the day before, and his primary concern was avoiding a stall. The combination of pushing the control column forward more than necessary and a turning flight path made the jettison ineffective. During the pull-up to avoid hitting the ground, the jettison rate increased, but approximately one-third of the load remained aboard after the accident.
Post-Accident Findings and Recommendations
A recommendation was made and accepted for the pilot to receive additional dual instruction on the aircraft's stall characteristics, with an emphasis on speed margins during low-speed maneuvering. The agricultural operators association was requested to remind its members about the effect of maneuvering on jettison system performance.