Accident Details
Two witnesses reported observing a banner tow airplane release its aerial sign at an airstrip adjacent to a highway. The aircraft subsequently entered a steep pitch-up attitude, followed by a steep left turn toward the highway at an altitude described as lower than the treetops. One witness noted that the left wing appeared nearly vertical before the nose pitched downward and the airplane struck the ground.
Aircraft Information
The owner's handbook for the Super Cub 135, referenced in the investigation, provides stalling speed data. According to Section II (Take-off, Climb, and Stalls), the gross weight power-off stalling speed with full flaps is 38 mph, and with flaps up, the stalling speed increases by approximately 4 mph.
Post-Accident Examination
A physical examination of the airframe, flight controls, engine assembly, and accessories revealed no anomalies that could have contributed to the accident. No mechanical or structural failures were identified during the inspection.