On November 9, 2004, about 0420 mountain standard time, a Swearingen SA226TC, N162WA, sustained substantial damage after colliding with the runway 10R approach lighting system at the Boise Air Terminal (Gowen Field), Boise, Idaho. The airplane is registered to Western Airlines LC of Boise, Idaho, and was being operated by Western Air Express as a domestic non-scheduled cargo flight under the provisions of Title 14 CFR Part 135, when the accident occurred. The commercial pilot, the sole occupant of the airplane, was not injured. Instrument meteorological conditions were reported at Boise at 0353 and 0436. The flight originated at Salt Lake City, Utah, (SLC) on an instrument flight rules (IFR) flight plan at 0310. The pilot's flight planned destination was Boise, with Twin Falls, Idaho, as an alternate. In a written statement the pilot reported that while holding at the outer marker, the Boise tower advised him that the runway visual range (RVR) was 1800 and cleared him for the approach. The pilot stated that he "...picked up the glide slope, lowered the landing gear, and continued on normal descent. At approximately 250 AGL I picked up the glow of the rabbit, at 200 feet (3,036' [feet] on the altimeter) I looked outside and could see the rabbit and approach lights. I then continued to 100' [feet] where I could see the runway and continued to a normal landing. During my transition from instruments to visual at 2,936' [feet] I apparently went below the glide slope and took out two approach lights." The 0436 Boise SPECI METAR observation reported weather conditions, in part, as: visibility 1/4 statute mile in fog; scattered clouds at 100 feet AGL (above ground level); overcast skies at 600 feet AGL. The published decision height/altitude for the straight-in ILS runway 10R approach at Boise is 3,036 feet above mean sea level (200 feet AGL). The published minimum visibility for a straight-in ILS approach is 1/2 mile or an RVR of 1,800 feet.