Cessna 172 N8620B accident near Lakeway, Texas

Probable cause

A partial loss of engine power for reasons that could not be determined, and the flight instructor's exceedance of the airplane's critical angle of attack while maneuvering for a forced landing, which resulted in an aerodynamic stall and subsequent loss of control.

NTSB analysis

The flight instructor and student pilot were conducting takeoffs and landings in the airport traffic pattern. A flight instructor and pilot on the ground reported that the accident airplane's engine was "cutting in and out" or "sputtering" following an aborted landing. Both witnesses reported that the airplane appeared to be maneuvering to return to the runway when the airplane entered a left turn, then descended in a steep, nose-down attitude consistent with an aerodynamic stall. The common traffic advisory frequency recording captured a transmission that indicated the flight instructor might attempt to return to the airport. The airplane impacted a tree and then a road sign in a mostly residential area.

A postaccident examination of the airframe and engine revealed no mechanical malfunctions that would have precluded normal operation. The propeller exhibited signs of rotation and propeller strike marks were found on the ground at the accident site. Although the witness reports indicated a possible loss of power, the reason for the partial loss of engine power could not be determined based on the postaccident examination. After the partial loss of engine power, the flight instructor attempted a turn at low altitude, during which he failed to maintain proper airspeed and exceeded the airplane's critical angle of attack, which resulted in an aerodynamic stall and a loss of control at an altitude too low for recovery.

Text from the NTSB. Open the NTSB docket for CEN19FA099 for the full record.