The pilot reported he was conducting stop-and-go-landings in a tailwheel-equipped airplane to a dry, gravel runway. During the third landing, he reported all three wheels from the landing gear were in contact with the runway and he slowed with normal braking application. He reported that he abruptly felt the tail of the airplane lift, the propeller impacted terrain, and the airplane nosed over. The airplane sustained substantial damage to the fuselage, the right wing struts, and the rudder. During a telephone conversation with the National Transportation Safety Board investigator-in-charge, the pilot stated that he was unsure if a tail wind or his braking application caused the airplane to nose over. The pilot reported there were no preimpact mechanical failures or malfunctions with the airframe or engine that would have precluded normal operation. The pilot wore a surplus U.S. Navy Flight Deck Crewman's helmet for the flight in addition to utilizing a four-point restraint system. He reported that if he was not wearing a helmet, the injuries sustained to his face, head, and brain would have been serious or fatal. The closest weather reporting facility was the Wasilla Airport, Wasilla, Alaska, about 20 miles southeast of the accident site. At 1556, an Aviation Routine Weather Report (METAR) was reporting in part: wind, calm. In the weather section of the National Transportation Safety Board Accident/Incident Reporting Form 6120.1, the pilot reported the wind direction was variable and the wind speed was light and variable at the accident site. The Federal Aviation Administration (FAA) has published the Airplane Flying Handbook FAA-H-8083-3A (2004). This handbook discusses braking application procedures for tailwheel-equipped airplanes and states in part: Some models of tailwheel airplanes are equipped with heel brakes rather than toe brakes. In either configuration the brakes are used primarily to stop the airplane at a desired point, to slow the airplane, or as an aid in making a sharp controlled turn. Whenever used, they must be applied smoothly, evenly, and cautiously at all times. The FAA and the Medallion Foundation has published the Alaska Flight Review Guide (2014). This guide discusses aviation life support equipment and states in part: Considering the type of aircraft and mission, a helmet may help survive an accident. The U.S. military and European community has established standards for flying helmets. Emphasize the importance of choosing a helmet which meets an appropriate standard for the type of operation, and which is kept in good repair. Fatal and serious injury data suggests that helmets are most useful in tandem seat aircraft. A three-point harness is the minimum installation recommended for both front and back seats. The four and five point harnesses are a great improvement to the security of the user due to the geometry of the belts installation. Any properly installed and worn shoulder harness is an improvement over no shoulder harness at all.