On July 12, 2000, at 1845 hours Pacific daylight time, a Cessna 337G, N3273D, landed gear up at the Battle Mountain, Nevada, airport. The airplane was operated by the U.S. Department of Interior, Bureau of Land Management as a public-use flight, under 14 CFR Part 91, and sustained substantial damage. The commercial pilot and one passenger were not injured. Visual meteorological conditions existed for the cross-country flight that departed the Boise, Idaho airport at 1730, and was scheduled to terminate at Battle Mountain. A visual flight rules (VFR) flight plan had been filed. In an interview with a Federal Aviation Administration inspector, the pilot stated that he forgot to put the landing gear down. He indicated that because he had kept his airspeed up during the descent for a high altitude landing, the landing gear warning horn did not activate. He had flown the airplane earlier that day from Battle Mountain to Boise to exchange firefighting crews, and no discrepancies were noted with the landing gear system. In an interview with an Air Safety Investigator from the U.S. Department of the Interior, Office of Aircraft Services, the pilot stated that during the landing flare he did not hear the landing gear warning horn sound. He reported that he did not check that the landing gear green light was illuminated, or visually verify with the mirror located on the outside of the airplane to see if the landing gear was extended. He further stated that he did not verify that the landing gear handle was in the down position. The pilot indicated that he did not follow a mental or printed checklist for landing, and that there was not a printed checklist for putting the landing gear down.