On December 4, 2003, about 2015 Pacific standard time, a Cessna 525, N15C, experienced a loss of control during landing and sheared the nose gear off in a collision with a taxiway pavement lip edge at Montgomery Field Airport, San Diego, California. Polestar Labs Inc., was operating the airplane under the provisions of 14 CFR Part 91. The private pilot and two passengers were not injured; the airplane sustained substantial damage. The flight departed the Mahlon Sweet Field Airport, Eugene, Oregon, about 1800, with a planned destination of San Diego. Instrument meteorological conditions prevailed, and an instrument flight rules (IFR) flight plan had been filed. In a telephone interview, the pilot stated he was able to see the field while intercepting the instrument approach course at 3,000 feet mean sea level (msl). Using instruments for the approach, he was still able to maintain visual contact through the 100-200 feet of fog, when he reached 200 feet above ground level (agl). After descending, he lost visual contact with the runway, and everything became black. He started to move the levers up for a go-around, but noticed two red lights to his left. He thought he was too close to the ground and too slow, so he decided to land. The airplane touched down on the runway a second or two later. The pilot did not maintain directional control and the airplane veered to the left. It crossed an unpaved area, then hit and crossed a taxiway. The pavement lip edge broke the nose wheel off. The airplane continued onto another unpaved area and came to rest. It was about 50 feet to the left of runway 28R, and about 100 feet to the right of runway 5. The airplane also incurred damage to the nose gear fork assembly, pressure vessel, and to frame members. A routine aviation weather report (METAR) for Montgomery Field Airport was issued at 2018. It stated: skies partially obscured with fog; vertical visibility of 100 feet; visibility less than 1/4 mile; winds from 350 degrees at 3 knots; temperature 52 degrees Fahrenheit; dew point 52 degrees Fahrenheit; and altimeter 30.06 inHg. The pilot stated that the accident could have been prevented had he initiated a go-around when he lost visual contact with the runway. He reported no preimpact mechanical malfunctions or failures with the airplane.