On March 26, 1998, at 0405 central standard time, a Cessna 310R, N3700G, U.S. Check flight 291, operated by Airnet Systems, Inc., collided with the terrain during a gear-up landing at the Joe Foss Field, Sioux Falls, South Dakota. The 14 CFR Part 135, cargo flight was operating in visual meteorological conditions. The pilot was not injured and the airplane received substantial damage. The flight originated from Des Moines, Iowa, at 0253 cst. The pilot reported he checked the weather conditions 15 to 20 minutes prior to reaching his destination airport. The winds at that time were being reported as gusty and variable, favoring runway 21. He continued to report that upon reaching the airport, he entered a left downwind for runway 21 at mid-field. He reported he adjusted for the crosswind condition, but his corrections were not enough. This resulted in him making a single 180 degree turn from downwind to final approach. He reported, "By making a single turn to final, I broke out of my usual habit of lowering the gear on the base leg. Once on final, I was occupied with correcting my flight path to attain runway centerline and the proper glide path (as per VASIs)." The airplane was landed with the landing gear in the retracted position. The pilot reported he did not recall hearing a landing gear warning horn when he retarded the throttles.