On August 10, 1997, at 1855 central daylight time, a Balloon Works Firefly 7B-15, N90755, operated by a balloon pilot, experienced a hard landing near Columbia, Missouri. The passenger sustained serious injuries. The pilot was not injured and the balloon was not damaged. The personal flight was operating under 14 CFR Part 91. Visual meteorological conditions prevailed at the time of the accident and no flight plan was on file. The local flight departed the Boone County Fairgrounds, Columbia, Missouri at 1830 cdt. The pilot in command of the balloon was participating in the United States National Hot Air Balloon Championships. His only passenger had won a balloon ride in N90755. In a written statement, the pilot stated that prior to the flight, he attended three weather briefings. The first two briefings indicated a cold front approaching from the northwest, associated with rain and thunderstorms. The event was put on hold by the weather official, pending an improvement in the weather. According to the pilot, the third briefing, held at 6:15pm cdt, indicated that the "system had dissipated and that extremely calm winds should remain for the duration of the flight time." The event was then cancelled due to the near no-wind conditions. At this time, the pilot elected to fly. The pilot stated that he briefed his passenger "on his duties and on hard landing techniques." The balloon launched with approximately 10-15 other balloons. The pilot reported that approximately thirty minutes into the flight, the wind shifted 180 degrees and accelerated. He elected to descend for landing in a field. During the landing sequence, one corner of the basket contacted the ground, causing the basket to pirouette onto one side. The pilot stated that the passenger's foot got caught between the propane tank and the basket resulting in a fractured ankle.