On March 12, 1994, at 1035 mountain standard time, an American Champion 8KCAB, N189AC, collided with terrain while engaged in aerobatic maneuvers near Marana, Arizona. Visual meteorological conditions prevailed at the time and no flight plan was filed. The aircraft was destroyed in the ground collision sequence and the airline transport pilot, the sole occupant, sustained fatal injuries. The flight originated from the Avra Valley airport on the day of the accident at 1015 hours for a local area aerobatic flight. The accident was witnessed by several International Aerobatic Club judges, who were grading the pilot's aerobatic routine. According to the witnesses, the pilot performed the 1994 Intermediate Known Sequence, which was to be followed by a hammerhead turn course reversal to include a 1/4 roll on the up line and a 1/4 roll on the down line. After the hammerhead turn, the aircraft was descending on the vertical line and the witnesses did not see the pilot attempt to pull out until very near the ground when a 10- to 15-degree attitude change was noted. The witnesses said the engine continued at near full power throughout the maneuver to ground impact. According to a Federal Aviation Administration (FAA) inspector, ground scars and the extensively fragmented aircraft wreckage debris were found distributed on the flat desert terrain on a southeast to northwest line. A median bearing line through the ground scars and debris measured about 500 feet in length. At the request of the National Transportation Safety Board, the aircraft was examined by the holder of an FAA airframe and powerplant mechanic's certificate, who also holds an inspection authorization. According to his written report of the examination, all of the aircraft components were accounted for in the wreckage path. The entire flight control system was documented, with no discrepancies noted. An autopsy was performed by the Pima County Medical Examiner's Office, with specimens retained for toxicological analysis. The analysis was performed by the FAA Civil Aeromedical Institute, who reported negative results for alcohol and all screened drug substances.