On February 9, 2005, about 1645 mountain standard time, a passenger fell and fractured her collarbone while boarding a Cameron Balloon A-250, N3037V, near Cave Creek Arizona. Hot Air Expeditions was operating the balloon under the provisions of 14 CFR Part 91. The commercial pilot and two passengers were not injured; one passenger sustained serious injuries. The balloon was not damaged. The local sightseeing flight was boarding prior to departure, and was to land elsewhere in Cave Creek. Day visual meteorological conditions prevailed, and a visual flight rules (VFR) flight plan had not been filed. The pilot submitted a Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1/2). He stated that, prior to the envelope's hot air inflation, he had two of the passengers preboard the balloon due to one of the female passenger's physical limitations and speed of the surface wind. He stated that the estimated surface wind was 4-5 mph. As he started hot air inflation of the balloon, the envelope started to stand upright. At that time, he instructed the third passenger to board. As she started to climb up using the footholds, the side of the basket that she was on lifted off the ground causing her to lose her balance and fall to the floor of the basket. A medical examination revealed that she had a broken collarbone. The pilot stated that the balloon and heater had no mechanical failures or malfunctions during the flight.