On January 11, 2004, about 1830 Pacific standard time, a Cessna 140, N77S, collided with a tree during a forced landing at Vacaville, California. The pilot/owner was operating the airplane under the provisions of 14 CFR Part 91. The non-instrument rated commercial pilot and one passenger sustained serious injuries; the airplane sustained substantial damage. Visual meteorological conditions prevailed, and a flight plan had not been filed. The personal 18-mile cross-country flight originated at Napa County Airport, Napa, California, about 1730, with a planned destination of Nut Tree Airport, Vacaville. In a written statement, the pilot reported that earlier in the day he had completed a trip from Vacaville to Napa. Prior to departure, he estimated that his total time en route for the short cross-country trip back would be about 15 minutes. With consideration of fuel on board the airplane, he estimated that he had enough fuel to complete the trip and meet the Federal Aviation Administration (FAA) required night-flight 45-minute reserve. After departing, the pilot received the weather information for Nut Tree Airport via the airport's automated weather observation station (AWOS), which revealed deteriorated conditions. As the airplane approached the vicinity of the airport in dark night conditions, the pilot noted that a fog layer had approached from the south, and he could not obtain visual contact with the airport or surrounding terrain. The pilot further stated that he exhausted the right fuel tank and switched to the left. With knowledge of the rough terrain on the flight back to Napa, the pilot opted to declare an emergency on frequency 121.5. He was instructed to contact Travis Approach control, who attempted to give him vectors back to Nut Tree Airport, despite his requests to be vectored to Travis Air Force Base. He exhausted the left fuel tank and the engine subsequently quit. The pilot established a gliding configuration, and the airplane descended into the fog about 700 feet above ground level (agl). The airplane collided with a small tree and then encountered a berm, coming to rest about 50 to 60 feet after the initial impact (around Highway 505 and Vacaville Parkway). The airplane incurred damage to the tail section and right wing. An FAA inspector examined the airplane at the accident site and reported finding the left fuel tank empty; he drained 3 quarts of fuel from the right tank. He stated that the fuel had an odor consistent with that of automobile gasoline. At 1753, the weather observation facility at the Nut Tree Airport reported the wind from 130 degrees at 4 knots; fog; vertical visibility 100 feet; temperature 09 degrees Celsius; dew point 09 degrees Celsius; and the altimeter was 30.00 inHg. At 1853, the facility reported the wind from 110 degrees at 5 knots; fog; vertical visibility 100 feet; temperature 09 degrees Celsius; dew point 09 degrees Celsius; and the altimeter was 30.01 inHg.