On October 28, 1997, at 0941 hours mountain standard time, a Cessna 152, N49788, veered off runway 21R during landing, collided with a ditch and nosed over at the Prescott, Arizona, airport. The aircraft sustained substantial damage. The flight instructor and the dual student were not injured. The local area instructional flight originated at Prescott at 0900. The instructor reported that the student flared abruptly and the aircraft ballooned. As the aircraft touched down, it immediately turned violently to the left. The instructor said he got on the controls and applied right rudder to stop the turn; however, the aircraft left the paved surface, encountered a drainage swale in the grassy area between the runways, and nosed over. The instructor stated that there was no mechanical malfunction of the aircraft prior to the accident.