The pilot had driven from his home along Highway 199 on the afternoon of the accident. The highway traverses the Coastal Mountain Range through a narrow winding valley and is the most direct route from Gasquet to Yreka. The pilot was going to fly the aircraft to Yreka for an annual inspection. The pilot did not obtain a preflight weather briefing. A pilot witness at the airport said the aircraft departed on runway 6 then maintained about 200 feet AGL as it flew eastbound over the highway. The weather was 600 ft overcast, with good visibility beneath. Another witness was driving on the highway when the aircraft overflew him just below the clouds at 700 ft AGL. The bases of the clouds were below the tops of the surrounding mountain peaks. The accident site is on the western slopes of a 2,800 ft tall coastal mountain, located adjacent to and south of the highway. The elevation of the site is about 1,900 ft MSL. Impact marks and damage to trees indicated the aircraft struck the trees and the steep mountain slope in a level to slight climb attitude with little bank angle. The last entry recorded in the pilot's logbook was dated January 2, 1990. On the pilot's application for his medical certificate on May 1, 1991, he reported that he had not flown for the preceding six months.