Mooney M20J N1149T accident near Bartow, Florida

Probable cause

The pilot’s exceedance of the airplane's critical angle of attack and subsequent aerodynamic stall and spin at low altitude due to a possible distraction in the cockpit for which the reason was undetermined.

NTSB analysis

The accident pilot and his wife were assigned the No. 4 position in a formation flight. Flight data indicate that, throughout the flight, the accident airplane’s path, altitude, and speed closely followed those of the lead airplane. Approaching the landing airport, the flight-lead instructed the other pilots in the formation to “Go extended trail,” and all complied and were in-trail behind the flight lead to enter the traffic pattern. Subsequently, the accident airplane’s flightpath became irregular when, about 1,500 ft past the lead airplane’s turn, the accident airplane began a turn from downwind to base leg during which the bank angle varied from 5° to 20°. It leveled off on the base leg, then turned sharply right toward the runway, passing through the runway heading before turning left and steeply descending. Witnesses at the airport reported seeing the accident airplane “closing in” on airplane No. 3 before making a sharp right turn. The airplane impacted the ground about .6 nautical mile from the runway threshold.

Examination of the airplane revealed that the landing gear was in the UP position and the flaps were extended to 10°, which is not consistent with normal landing configuration upon the completion of the landing checklist, which should be performed on the downwind leg of the traffic pattern. No preimpact anomalies or malfunctions were identified during the examination that would have prevented normal operation.

Airplane manufacturer lift data indicated that for a no-flaps configuration, lift dropped off just before 15° angle of attack. The airplane’s calculated angle of attack increased to more than 14° immediately before the airplane descended rapidly to the ground. Although the airplane’s flap setting was likely 10°, the final seconds of the airplane’s flightpath were consistent with an aerodynamic stall and an entry phase of a spin at an altitude too low to recover.

Review of six detailed flight notebooks maintained by the pilot’s wife showed a multi-year history of in-flight notations of the times for every radio call, configuration change, entry in the traffic pattern, and turns within the traffic pattern. Given the failure of the pilot’s wife to note the time of entry into the downwind leg of the traffic pattern and the irregularity of the flightpath that commenced on the downwind leg of the traffic pattern, it is likely that there was a distraction in the cockpit around this time; however, the reason for the distraction could not be determined. The distraction likely led to his failure to lower his landing gear and flight control inputs that allowed the airplane to exceed its critical angle of attack, leading to an aerodynamic stall at low altitude. Review of the pilot’s medical history and medications revealed that the upset was unlikely to have been an effect of any of his medical conditions or his use of fluoxetine.

Text from the NTSB. Open the NTSB docket for ERA20FA101 for the full record.