NTSB Factual Report

The certificated flight instructor (CFI) was providing flight instruction to a certificated commercial pilot for a tailwheel endorsement under Title 14, CFR Part 91. The CFI reported that while on final approach to land, he inadvertently allowed the commercial pilot to descend prior to reaching their intended touchdown point. He said that his verbal command to initiate a go-around was not followed by the commercial pilot, and that he was unable to move the commercial pilot's hand from the throttle in order to add full engine power. The airplane drifted to the right and struck a VASI light box. The airplane sustained substantial damage to the left wing, left wing lift strut, and fuselage. The CFI noted that there were no preaccident mechanical anomalies with the airplane.

NTSB Probable Cause

The flight instructor's inadequate supervision of the student while landing, which resulted in an undershoot and an in-flight collision with an object. Factors contributing to the accident are the dual student's misjudged altitude/distance and delayed response in relinquishing the flight controls.