Primary finding
Probable cause
the pilot's failure to plan to avoid wake turbulence.
Investigator assessment
Analysis narrative
The pilot was conducting an aerial application flight in a close area. During the procedure turn the pilot encountered the airplane's wake turbulence. During the recovery, the airplane stalled and collided with the terrain.
Source record
Factual narrative
On September 30, 1995 at 1838 hours mountain standard time, a Grumman G-164B, N6779K, crashed while executing an aerial application maneuver at Avondale, Arizona. The pilot was conducting a visual flight rules aerial application flight under the provisions of 14 CFR Part 137. The airplane, operated by Moseley Aviation, Inc., Avondale, Arizona, sustained substantial damage. The certificated commercial pilot, the sole occupant, was not injured. Visual meteorological conditions prevailed. The flight originated from the operator's airstrip at Avondale at 1815 hours. National Transportation Safety Board investigators interviewed the operator via the telephone on September 30, 1995. The operator said that the airplane stalled when the pilot was executing a procedure turn maneuver. The pilot submitted the required Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1/2. He said in the report that he elected to execute shorter radius turns while spraying a half section of a field. He normally sprays the field using a wide circling pattern. During the turn, the pilot encountered the airplane's wake turbulence. He pushed the control yoke forward to recover from the turbulence, but the airplane's altitude was insufficient to effect a normal recovery and the airplane struck the ground. The pilot also indicated in the report that the airplane did not experience any preexisting malfunctions or failures. -