Amateur-built Acroduster II N787WM accident near Phoenix, Arizona

Probable cause

An exceedance of the airplane's critical angle of attack while maneuvering for landing, which resulted in an aerodynamic stall/spin at an altitude too low for recovery.

NTSB analysis

The two private pilots on board the experimental amateur-built airplane had purchased the airplane 2 days before the accident. On the day of the sale, the previous owner provided the rear-seat accident pilot with a 2.5-hour familiarization flight. He stated that he had no issues with the pilot's performance, but he did suggest that the accident pilot obtain some instruction from a flight instructor to become more familiar with the airplane, to which the accident pilot replied that he didn't have time and that he felt comfortable with the airplane.

On the morning of the accident, the pilots performed 4 takeoffs and landings in the airport traffic pattern, each of which was uneventful. During the 5th circuit in the traffic pattern, onboard video revealed that the airplane's nose pitched up slightly just before the airplane entered the left turn onto the base leg. As the airplane continued to turn left, it appeared to exhibit aerodynamic buffeting. The airplane rolled right, then immediately rolled left as the nose pitched down and the airplane began to rapidly descend. The airplane rolled from a 90° left bank to a 90° right bank and continued to descend in a nose-low attitude while rolling left and right before impacting terrain. Postaccident examination of the airplane and engine revealed no anomalies that would have precluded normal operation.

It could not be determined which of the two pilots was manipulating the flight controls at the time of the accident, and no personal logbooks for either pilot were available for review; therefore, the pilots' flight experience and recency of experience could not be determined. The onboard video of the flight was consistent with an exceedance of the airplane's critical angle of attack while maneuvering in the airport traffic pattern, which resulted in an aerodynamic stall/spin at an altitude too low for recovery.

Text from the NTSB. Open the NTSB docket for WPR18FA229 for the full record.