The pilot of a tailwheel equipped airplane reported that he was landing on a backcountry airstrip. He reported that after touchdown, about two-thirds of the way down the runway during the landing roll, the wind shifted to a tailwind. He further reported that the airplane over ran the runway, impacted a hill, and nosed over. The airplane sustained substantial damage to the empennage. The pilot reported no preaccident mechanical malfunctions or failures with the airplane that would have precluded normal operation. According to the pilot the wind was variable at 7-8 knots prior to the accident. The Federal Aviation Administration has published the Advisory Circular (AC) 91-79A. This AC discusses the hazards associated with runway overruns and the effect of a tailwind on landing distance and states in part: The pilot must be aware of airspeed during the approach and of the targeted reference landing airspeed (VREF)/airspeed, plus wind gust adjustments, over the runway threshold. An excessive approach speed may result in an excessive speed over the runway's threshold, which may result in landing beyond the intended touchdown point as well as a higher speed from which the pilot must bring the airplane to a stop. The effect of a tailwind on landing distance is significant and is a factor in determining the landing distance required. Given the airplane will land at a particular airspeed, independent of the wind, the principal effect of a tailwind on operational landing distance is the change in the ground speed at which the airplane touches down.