What happened
Two witnesses observed a Super Cub 135 performing a banner tow operation at an airstrip located adjacent to a highway. During the operation, the aircraft released its banner aerial sign. Following the release, the airplane entered a steep pitch-up attitude and subsequently executed a steep left turn toward the highway. This maneuver occurred at an altitude lower than the surrounding treetops. One witness reported that the left wing reached a near-vertical position relative to the ground before the nose of the aircraft pitched down, resulting in a collision with the ground.
The investigation
An examination of the airframe, flight controls, engine assembly, and accessories was conducted. The inspection revealed no anomalies in the mechanical components of the aircraft.