On August 23, 1993, at 1115 hours Pacific daylight time, a Cessna A150M, N9861J, exited runway 16 at Natomas Field, Sacramento, California, and nosed over. The pilots were conducting a local visual flight rules instructional flight. The airplane, registered to Sacramento Aero Services, Inc., and operated by American Aero Club, Inc., Natomas, California, sustained substantial damage. Neither the certificated commercial pilot/flight instructor (CFI) nor the noncertificated student pilot was injured. Visual meteorological conditions prevailed. The flight originated at Natomas Field at 0945 hours. Neither the CFI nor the operator informed the Safety Board of this accident. An anonymous person informed the Federal Aviation Administration (FAA), Sacramento Flight Standards District Office of this accident on August 26, 1993. A FAA flight standards inspector examined the airplane and determined that the airplane had sustained structural damage. Both the CFI and the operator submitted an unsigned Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1/2. The CFI reported that after completing airwork at the practice area the flight returned to Natomas Field for traffic pattern instruction. On the first approach the CFI instructed the student to execute a go-around. The student satisfactorily completed the go-around and re-entered the traffic pattern for a second approach to a landing. During the landing roll the student pilot began to instinctively control the airplane as if he was driving an automobile by stepping on the right rudder pedal to slow the airplane. This action caused the airplane to veer to the right. The student panicked during the sudden departure from the centerline. The CFI advised the student that he assumed the controls, but the student froze on the controls and continued to operate the controls as if he were driving an automobile to arrest the right excursion. The CFI was unable to regain control of the airplane. The airplane exited the asphalt surface runway and entered the soft dirt. The airplane continued its landing roll until the nose gear collapsed and the airplane nosed over onto its back.