CAVE CREEK, AZ, USA
N7021U
Balloon Works FIREFLY 11
While attempting a high wind landing, the balloon hit hard and one passenger sustained serious injuries. The pilot checked weather prior to departure, and said that at 0610, the weather was mostly cloudy with surface winds from the south at 3 to 5 mph. About 0635, the nearby Deer Valley airport ATCT told the pilot that surface winds were 12 knots from 220 degrees. In addition, another company pilot told him by radio that surface winds in his location were now 25 mph. The pilot's ground crew also confirmed that surface winds had increased substantially. The pilot said that he was 3,000 feet msl when the change in wind velocity was reported, and he selected an alternate landing site and briefed his passengers on high wind landing procedures. The approach was initiated at a descent rate of 700 fpm. During this time he told the two standing passengers to sit down because they would be experiencing a very rough landing. After descending through 500 feet agl at 700 fpm, the balloon's vertical sink rate suddenly increased substantially. He said this encounter had caused distortion in the envelope that resulted in the envelope losing hot air (lift), and increasing his rate of descent. His attempt to slow the descent in the time remaining was unsuccessful and the balloon landed short of the intended site, rebounded into the air, and then skidded about 100 yards before coming to a stop with the carriage lying on its side. Another balloon pilot, who saw the landing, said that the balloon appeared to have encountered a sudden microburst that resulted in an inadvertent hard landing. Other witnesses described the final descent as rapid, and noted that the envelope was distorted (flattened) downward as if the balloon was being pushed down. According to the FAA approved performance data sheet, terminal velocity (Vt) of the balloon under maximum gross weight conditions is 1,200 fpm with a recovery time to equilibrium 90 seconds, and altitude lost during recovery (from application of burner to equilibrium) to be 1,000 feet. The POH states that should weather conditions deteriorate while in flight, the pilot should land immediately, and "to risk damage if necessary to land while the flight is still under control." The manufacturer reported that the maximum demonstrated wind speed at landing during certification testing was 7 knots.
HISTORY OF FLIGHT On August 19, 1999, at 0710 hours mountain standard time, a Balloon Works Firefly 11 balloon, N7021U, landed hard in open desert terrain north of East Carefree Highway and North 48th Street in Cave Creek, Arizona. The balloon received minor damage. One passenger sustained serious injuries, four sustained minor injuries, and the pilot and remaining seven passengers were reported as not injured. Hot Air Balloon Expeditions, Inc., was operating the balloon as a for-hire sightseeing flight under the provisions of 14 CFR Part 91 when the accident occurred. The flight originated from open desert terrain west of North 40th Street and East Lone Mountain Road in Cave Creek about 0610. Visual meteorological conditions prevailed at the time and a company flight plan was filed. The pilot reported that prior to departure he obtained the 0300 and 0400 weather reports for Phoenix, Arizona, from the National Weather Service. He watched the Weather Channel on television from 0345 until 0430. At the departure site several pilot balloons were launched and observed to determine local winds aloft patterns. The pilot of N70535, another company balloon, relayed a weather briefing that had been obtained from Prescott Flight Service Station (FSS). At the time of departure, he reported that the weather was mostly cloudy with surface winds from the south at 3 to 5 mph. About 0635, the pilot of N70535 called the tower at Deer Valley airport for a wind check. He was told that surface winds had increased to 12 knots from 220 degrees. At the time, the pilot reported that he was en route to the targeted landing site at 3,000 feet msl when the change in wind velocity was relayed to him. Immediately after that radio transmission, the pilot of a third company balloon reported that surface winds in his location were now 25 mph. The pilot's ground crew also confirmed via radio that surface winds had increased substantially. Because of the increase in velocity, the pilot selected an alternate landing site and briefed his passengers on high wind landing procedures. Beginning his descent near Carefree Highway and 49th Street, he said that of the 12 passengers, 10 sat on the floor of the carriage and grasped handholds. The approach was initiated at a descent rate of 700 fpm. During this time he told the two standing passengers to sit down because they would be experiencing a very rough landing. After descending through 500 feet agl at 700 fpm, the balloon's vertical sink rate suddenly increased and the pilot turned his attention to the task of landing the balloon. He said this encounter had distorted the envelope, which resulted in the envelope losing hot air (lift), and increasing his rate of descent. His attempt to slow the descent in the time remaining was unsuccessful. Prior to touchdown, the pilot shutoff the fuel to the burner and prepared to pull the envelope valve line upon contact with the ground. With the unplanned increase in the rate of descent, the balloon landed short of the intended site, rebounded into the air, and then skidded about 100 yards before coming to a stop with the carriage lying on its side. When asked by investigators, he did not report any discrepancies or malfunctions relating to the performance of the balloon or its equipment. A company pilot in another balloon, who was watching the approach, reported that the balloon appeared to have encountered a sudden microburst that resulted in an inadvertent hard landing. Other witnesses described the final descent as rapid, and noted that the envelope was distorted (flattened) downward as if the balloon was being pushed down. The pilot reported that soon after landing the surface winds calmed. The seriously injured passenger stated that she was too frightened to sit as the pilot had directed. Her husband, who received minor injuries, reported that he had remained standing during the descent because he was trying to push his wife down to a seated position. PERSONNEL INFORMATION The pilot was a full-time employee of the operator. The operator does not maintain, nor is he required to maintain, training records for his employees. According to Federal Aviation Administration (FAA) records, the pilot was issued his commercial lighter-than-air free balloon certificate on February 6, 1984. He had previously logged 57 hours in this make and model, with a total of 4,011 flight hours in lighter-than-air free balloons. He is not rated in any other aircraft categories. Although a medical certificate was not required for this flight, he previously held a class II medical certificate that had been issued on November 21, 1980. He also reported logging 11 hours of flight in single engine airplanes. He had no previously reported accident history. AIRCRAFT INFORMATION According to the FAA approved maximum gross weights and performance data sheet, at the time of the accident the balloon was within the prescribed maximum gross weight limitations. The chart shows that terminal velocity (Vt) of the balloon under maximum gross weight conditions to be 1,200 fpm; the time to recover (Tr) from Vt to equilibrium to be 90 seconds; and altitude lost during recovery (application of burner to equilibrium) to be 1,000 feet. The pilot's operating handbook (POH) states that should weather conditions deteriorate while in flight, the pilot should land immediately rather than to fly into severe atmospheric turmoil. Risk damage if necessary to land while the flight is still under control. If caught in turbulence . . . Be very cautious about using the envelope valve of a cooled envelope. Over-valving may cause rapid descent into turbulence or wind shear and tend to collapse the envelope. The manufacturer defines a hard landing as any landing in which the rate of descent exceeds 500 fpm. The POH cautions pilots by stating "Do not fly if turbulence, strong wind shears, or thermic or thunderstorm activity exist or are likely to be encountered during the flight." The manufacturer reported that the maximum demonstrated wind speed at landing during certification testing was 7 knots. A review of the balloon logbook by a Safety Board investigator revealed that the airworthiness certificate had been issued on March 7, 1999, and the last annual inspection, which was also the last inspection, had been performed on August 17, 1999. The balloon had flown 1.1 hours since the annual inspection, and there were no open entries for discrepancies or entries for unscheduled maintenance. COMMUNICATIONS The pilot was in two-way radio communication with other pilots and his support crew on the ground. There were no reported communication problems. WRECKAGE AND IMPACT INFORMQATION The operator had recovered the balloon to The Balloon Ranch, Phoenix, Arizona, a repair and inspection facility, before the arrival of the Safety Board investigator. When the investigator arrived, inspection and repair work had already commenced. The only visible damage to the balloon was to the wicker carriage, which exhibited scrapes along the bottom edge, and to one of the burners, which was dented. Photographs of the accident site showed evidence of several rebounds and scrape marks over a distance of approximately 100 yards. MEDICAL AND PATHOLOGICAL INFORMATION A toxicological examination was not performed. Deputies from the Maricopa County Sheriff's Office and firemen from the Rural Metro Fire Department responded to the scene. According to their report, the seriously injured passenger was transported by helicopter to John C. Lincoln Hospital, Phoenix. Two other passengers with minor injuries were also transported by ambulance to John C. Lincoln Hospital. The remaining passengers refused medical attention and remained at the scene. The operator later transported them from the scene. Another passenger, who was initially listed as not injured, was taken to the Grand Canyon Health Center, Grand Canyon, Arizona, later in the day. She was diagnosed with a fractured metatarsal. SURVIVAL ASPECTS The carriage does not provide seats or passive restraints. According to the POH, during hard landings, passengers are instructed to sit on the floor and to grasp onto handholds that are secured to the carriage. ADDITIONAL INFORMATION Maricopa County Sheriff's Deputies provided the photographs included with this report. An emergency locator transmitter is not required for balloons. The Safety Board did not take physical custody of the balloon after the accident; therefore, no wreckage release was issued.
An unforecast encounter with a low level microburst that resulted in a distortion of the balloon envelope, an excessive outflow of hot air (loss of lift), creating an excessive rate of descent that was beyond the performance capability of the balloon to recover in the altitude available. The failure of a passenger to follow the emergency procedures directives of the pilot was a factor in this accident.
Source: NTSB Aviation Accident Database
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