Pilot’s Failure To Maintain Adequate Airspeed And His Exceedance Of The Airplane’s Critical Angle Of Attack

Location: Oshkosh, Wisconsin Accident Number: CEN23FA320
Date & Time: July 25, 2023, 07:33 Local Registration: N9549
Aircraft: Heath V-Strut Aircraft Damage: Substantial
Defining Event: Loss of control in flight Injuries: 1 Minor
Flight Conducted Under: Part 91: General aviation - Personal

Analysis: Shortly after takeoff the pilot turned the airplane to avoid flying over the perpendicular runway. He reported that during the turn the airplane stopped climbing. The pilot aimed the airplane toward a field and attempted a forced landing. During the landing the airplane came to rest inverted, which resulted in substantial damage to the fuselage, empennage, and both wings.

One witness stated that the airplane “looked sluggish,” with the nose of the airplane high. Several witnesses observed the left wing dip before the airplane descended below the tree line. Security video showed the left wing dropped and the airplane impacted the ground in a leftwing-low attitude.

A postaccident examination of the engine, flight controls, and related systems revealed no mechanical failures or malfunctions that would have precluded normal operations. The splintered damage to the propeller blade was consistent with power and rotation at the time of impact. The pilot also reported that there was nothing mechanically wrong with the airplane at the time of the accident.

Weather conditions at the time of the accident were conducive for serious icing at glide power. However, investigators were not able to determine if a partial loss of engine power due to the accumulation of carburetor icing during the ground taxi may have resulted in the loss of climb performance after takeoff. Given the witness description and the footage captured by the security camera, it is likely that the pilot failed to maintain adequate airspeed during the initial climb and turn, which resulted in the exceedance of the airplane’s critical angle of attack and an aerodynamic stall and a subsequent loss of control.

Probable Cause and Findings: The National Transportation Safety Board determines the probable cause(s) of this accident to be -- The pilot’s failure to maintain adequate airspeed and his exceedance of the airplane’s critical angle of attack, which resulted in an aerodynamic stall. 

FMI: www.ntsb.gov