On October 11, 1993, at 2050 eastern daylight time, a Cessna 172, N12657, ditched into Boone Lake about one-half mile short of the Tri-City Regional Airport, Blountville, Tennessee. The personal flight operated under 14 CFR Part 91 with a valid instrument flight clearance. Visual weather conditions prevailed at the time of the accident. The airplane sustained substantial damage and the private rated pilot was not injured. The flight departed Allentown, Pennsylvania, at approximately 1545. According to the pilot, after takeoff, the instrument flight was cleared to a cruise altitude of 10,000 feet. Weather conditions forced the flight to change altitude. As the flight approached the destination airport, the flight was cleared to descend to 3500 feet. Upon establishing radio contact with Tri-City Approach Control, the flight was issued radar vectors for the ILS Runway 5 approach. Approximately six miles from the runway, and five hours and ten minutes into the flight, the engine quit. The pilot selected a forced landing area at Boone Lake; he subsequently ditched the airplane into the lake. The pilot also stated that the maximum fuel endurance for this airplane is about five hours, and he failed to plan an additional fuel stop. No mechanical problems were reported by the pilot.