On February 24, 2002, about 1750 Pacific standard time, a Cessna 172N, N1977F, nosed over during a precautionary landing on the Fresno Radio Modelers airstrip about 11 miles east of Madera, California. The airplane was substantially damaged. The private pilot, who owned and operated the airplane, was not injured. Visual meteorological conditions prevailed, and no flight plan had been filed. The personal flight was performed under 14 CFR Part 91, and it originated from a private airstrip near Tranquillity, California, about 1630. The pilot reported to the National Transportation Safety Board investigator that during the flight he became concerned and uncertain regarding his location. It was foggy and was getting dark. The pilot stated that he had only planned to make a local area flight. He had departed from Tranquillity sometime after 1400, but he was not certain of the time. Being uncertain of his position, he made a precautionary landing. The pilot repeated that he landed because he was having difficulty flying due to the fog. A responding law enforcement officer from the Madera County Sheriff's Department reported to the Safety Board investigator that the length of the airstrip on which the pilot had landed was an estimated 650 to 700 feet, and it was principally intended for use by operators of radio controlled model airplanes. The officer indicated that during rollout, the airplane overran the end of the airstrip, impacted a berm, and nosed over. In addition, the officer reported that the pilot mentioned to him that during his flight he had become disoriented due to the presence of fog. The officer stated, however, that there was no fog in the area and the visibility was unrestricted. The two nearest facilities to the accident site that report aviation weather are located at the Madera and Fresno airports. They are about 15 miles west and 10 miles south, respectively, of the accident site. The elevations of the Madera and Fresno airports and the accident site are, respectively, 253 feet, 336 feet, and about 382 feet mean sea level. In pertinent part, no fog or obstructions to vision were reported at these airports during the time of the pilot's flight. Madera reported its visibility was 10 miles, and the sky condition was clear. Fresno reported its visibility was also 10 miles, and few clouds existed at 20,000 feet. Sunset occurred about 1750. Subsequently, members of the pilot's family completed the Safety Board's Aircraft Accident Report form for the pilot. The family members reported that several weeks after the mishap, the pilot was still confused regarding circumstances of the accident flight.