HISTORY OF FLIGHT On February 11, 1999, about 0836 hours mountain standard time, an Aerostar International, Inc., RX-9 balloon, N91067, owned and operated by the pilot, collided with houses during a landing attempt in Peoria, Arizona. Visual meteorological conditions prevailed, and no flight plan was filed for the 14 CFR Part 91 aerial sightseeing passenger flight. The balloon was substantially damaged. The commercial pilot and one passenger were seriously injured, and the other four passengers sustained minor injures. The revenue flight commenced from an open field north of Phoenix, Arizona, about 0743. The pilot reported that at takeoff the surface wind speed was about 3 knots. After flying over mostly open fields for between 35 and 40 minutes the wind speed increased to 15 knots, and he began looking for a suitable landing site. As the balloon approached the desired site which was beyond residential homes, a wind gust was encountered. The pilot reported he initially planned to make a long, shallow approach. However, when the wind gust was encountered the envelope lost volume, and the balloon rapidly descended. The pilot stated that he attempted to arrest the descent by firing both burners, but the descent continued. The pilot further reported that he finally pulled the balloon's red line, the parachute top opened, and the envelope vented. No mechanical problems were experienced during the flight. A ground-based witness reported observing the balloon suddenly descend as it approached the residential neighborhood. The witness observed the balloon impact the tile roof of a house. Thereafter, the gondola tipped 90 degrees onto its side. None of the occupants were ejected. The balloon then impacted the roof of an adjacent house, and it came to rest upon touching down hard in an open field. METEOROLOGICAL INFORMATION The pilot estimated that during landing the prevailing wind was from 360 degrees at 15 knots, with gusts to 20 knots. Because of the wind, the gondola was dragged approximately 300 feet before coming to a stop on its side. A review of recorded computer communications between the pilot and a Direct User Access Terminal (DUAT) vendor indicated the pilot requested and received weather information for the Phoenix area on February 11, 1999, at 0442. The pilot indicated that he did not obtain any additional weather information from the DUAT vendor prior to his departure. The weather information received by the pilot indicated that after 0400 the surface wind at the Phoenix Sky Harbor International Airport (about 18 miles southeast of the accident site) was forecast to be variable at 3 knots. After 0800, the wind was forecast to be from 050 degrees at 10 knots. Between 0900 and 1300, the wind was forecast to be temporarily at 050 degrees, 12 knots with gusts to 20 knots. In addition, the winds aloft in the Phoenix area were forecast at 3,000 and 6,000 feet msl to be from 030 degrees at 27 and 40 knots, respectively. No weather forecast was available for the two airports closest to the pilot's route of flight. These airports are the Phoenix-Deer Valley Airport and the Luke Air Force Base. Deer Valley is located about 8 miles east-northeast of the accident site, and its elevation is 1,476 feet msl. Luke is located about 11 miles southwest of the accident site, and its elevation is 1,090 feet msl. At 0753, Deer Valley reported its surface wind was from 030 degrees at 9 knots. At 0755, Luke reported its surface wind was from 010 degrees at 16 knots. ADDITIONAL INFORMATION The pilot stated that he had a functioning radio on board the balloon. He did not carry a global positioning satellite (GPS) receiver. (GPS receivers can provide pilots with real-time ground speed information.) At the time of the accident, the passengers were not wearing protective helmets as required by the balloon manufacturer. According to the manufacturer's FAA Approved Flight Manual, helmet usage was required during an emergency, hard, or high wind landing. Three of the five passengers had made their balloon ride reservations by telephoning Adventures Out West, a Colorado-based booking agent. The agent had contracted with the accident pilot for the carriage of the three passengers. The pilot reported that of the $110 to $125, which each passenger was to pay him for the flight, he would retain $100 per passenger.