On June 11, 2005, about 1700 Pacific daylight time, an Aviat Pitts S-1T experimental acrobatic airplane, N647J, impacted terrain near Fillmore, California, after the pilot was unable to recover from an intentional inverted flat spin. The owner was operating the airplane under the provisions of 14 CFR Part 91. The airline transport pilot, the sole occupant, sustained minor injuries; however, the airplane was destroyed. The local personal flight departed Camarillo Airport (CMA), Camarillo, California, about 1635, and flew to the Santa Paula acrobatic practice area. Visual meteorological conditions prevailed, and no flight plan had been filed. The approximate coordinates of the primary wreckage were 34 degrees 23 minutes north latitude and 118 degrees 59 minutes west longitude. The pilot submitted a written report in which he reported departing CMA and flying to the Santa Paula acrobatic practice area. After 20 minutes of practicing the International Aerobatics Club sportsman sequence, he climbed to 5,000 feet mean sea level (msl) to practice inverted flat spin entry and recovery. He raised the nose to a vertical position and then pulled the nose to about negative 20 degrees past vertical. He applied full left rudder and full forward elevator control. The airplane pitched above and below the horizon twice and then entered into a left turning inverted flat spin. After about one turn he reduced power to idle, and the nose lowered into a left turning inverted spin. The rotation of the spin rapidly increased and he applied full right rudder to stop the rotation. The airplane did approximately three fast rotations and did not respond to the pilot's control inputs. He then tried to recover by initiating the Gene Beggs method of recovery (power off, opposite rudder, let go of control stick). He had already done the first two steps of the recovery and so he only had to release the control stick. However, the airplane did not respond and the rotation appeared to increase. The pilot initiated a bailout about 1,000 feet above ground level (agl). His parachute canopy opened successfully and he landed after approximately 5 seconds. The airplane impacted the Santa Clara riverbed about 2 miles west of Fillmore, and about 50 feet from where the pilot landed. The pilot stated that the airplane and engine had no mechanical failures or malfunctions during the flight. The Flight Combat International Emergency Maneuver Training Program indicates that the following inverted spin recovery procedure is designed to achieve optimum anti-spin effect and is consistent with recommendations based on years of detailed spin research: power - idle, ailerons - neutral (if in doubt let go of aileron control), rudder - full opposite yaw direction, and elevator - aft through neutral. Hold these inputs until yaw rotation stops, then neutralize rudder, apply aft elevator to climb straight ahead, and add climb power.