DEN99FA004
DEN99FA004

HISTORY OF FLIGHT

On October 5, 1998, at 0911 mountain daylight time, a Cameron A-250 balloon, N4557W, was destroyed following impact with wires during approach to landing at Kirtland Air Force Base, near Albuquerque, New Mexico. The commercial pilot and 11 passengers were seriously injured; however, one passenger was fatally injured. The balloon, named the Wayfinder, was being operated by the pilot under Title 14 CFR Part 91. Visual meteorological conditions prevailed for the across town flight (estimated distance of 9.5 nautical miles [nm]) which originated at approximately 08000. No flight plan had been filed.

According to several passengers, they arrived at the launch site, near Coors Drive and Irving Blvd. NW, at approximately 0630, and they were each weighed for the flight. The pilot reported that the fatally injured passenger arrived in a wheel chair (she had recently broken her right ankle). He said that all the passengers were briefed on flight procedures (see attached documents). One of the passengers said that the whole departure operation "appeared well organized." At 0700, the pilot said that he and his ground crew inflated the balloon, but aborted the launch attempt due to excessive wind.

The pilot reported that at approximately 0745, the wind subsided, and a second launch was attempted. The balloon lifted off at 0800, and they drifted to the south-southeast. Several passengers reported that the first half of the ride went "smoothly," and soon after takeoff, they even touched down in the river. One passenger reported that the flight "seemed to be very low to the ground;" she said that she could see peoples faces in the cars below. The pilot reported that he intentionally stayed low (radar indicated that they stayed below 5,700 feet mean sea level [msl]) because of much faster wind above. A witness on the ground reported that the balloon was "flying very low across Interstate-25 and he could clearly see the passengers." FAA recorded transmission tapes indicate that the pilot radioed Albuquerque International Airport Air Traffic Control tower at 0844, and reported that he was "five miles south [of the airport] at 5,300 feet."

A witness (a pilot of another balloon) on the ground in the Kirtland Air Force Base (KAFB) housing area reported seeing the Wayfinder through the trees, and the balloon's envelope was swaying back and forth. He said that he believed that the balloon had landed. He reported that he was surprised to look back a moment later and saw that the balloon was flying again. The pilot reported that he was traveling towards the first set of wires at approximately 165 degrees at 11 knots, and he believed that he was 50 to 60 feet above them. A witness stated that "the balloon seemed to be just above tree level, maybe 20 feet above the trees, and as I was watching, it dipped down and seemed to hit something." The pilot stated that "the wind was knocked out of the balloon and it began to fall very fast." He fired 2 burners for 10 seconds, and then fired all 3 burners for an additional 5 seconds. He said that he did not rip his top out [for an emergency descent] because he was still over KAFB housing. When he realized that wire contact was imminent, he began turning off the fuel manifold valves (he managed to turn 2 of the 3 valves off).

The pilot said that he "heard a large bang," and he thought the stainless steel basket cables had contacted the transmission wires. He then became aware that one of the burners was firing, and he discovered that one of his control lines had become entangled in the blast valve handle. Subsequently, the balloon's Nomex scoop began to burn, and a 5 to 8 foot hole was made in the envelope approximately 4 feet above the envelope throat. Witnesses reported seeing sparking and a burst of flame near the balloon's burner. They said that the balloon slid horizontally along the wires for some distance, and was then pulled upward. The pilot reported that he did a quick examination of the balloon, and he believed that it was airworthy.

A witness reported that burnt fabric from the balloon was falling all around him. Another witness said that she could see a hole in the envelope, and she assumed that it (the balloon) was going to come down immediately. The pilot stated that after being released from the wires, the balloon rose very rapidly, and headed eastbound. Several witnesses said that they yelled to the pilot for him to land in the next big field. The pilot said that he did not immediately start venting hot air because he wanted the balloon to stabilize from the large heat input just before the wire contact. He reported checking his passengers, and that everyone was "ok."

The pilot reported that his temperature gauge and altimeter (both were electrical digital readouts) were inoperative. He said that as the balloon began to level off, he began to "puff-burn" to ensure a level flight. He then started a controlled step-down descent. He reported that as he descended, the balloon again turned back to the south (approximately 160 to 165 degrees). He stated that he selected a landing spot which had transmission wires on the approach edge of the field, but he believed that he would clear them by "about 20 feet." The pilot said that then they "encountered a rapid low level wind shear, and suddenly the balloon fell like a rock a second time." Several witnesses said that they saw the pilot fire his burners moments before contacting the wire. The pilot said that he fired his burners, and then proceeded to turn off his fuel valves. He stated that the Kevlar envelope cables impacted the lowest wire, and the basket was 15 to 25 feet above the ground.

One witness reported that the basket's longest rectangular side was heading due south. A witness reported that "the envelope cables hit the power lines with a good force first, jolting/rocking the basket and then severing those cables." The pilot said "I think the basket rotated 180 degrees and then fell to a 30 to 45 degree angle."

A witness reported that the balloon's Kevlar suspension cables impacted the lower transmission line, and the envelope swayed back and forth on the south side of the power lines. The witness further reported that 15 to 20 seconds went by when suddenly the east end of the basket dropped to a 30 to 45 degree angle as the Kevlar cables separated. He said that the "east side of the basket dropped (no one fell out at any time during the accident) and perhaps came back up a little." He said another 20 seconds passed and the basket began to fall in short jerks. Suddenly, he reported, the basket fell to the ground from approximately 15 to 20 feet, landing east end first with one of its longest sides facing south.

A witness reported that "I saw a series of ripples run through the envelope, similar to when a gondola touches down hard. Quickly afterward, the envelope catastrophically came apart, the lower parts rising high into the air before collapsing." A video taken of the accident revealed that the envelope inverted itself, allowing smoke filled hot air to be released, before falling back to the ground. A sergeant in the Air Force reported that he acquired a knife from a civilian, and cut some of the remaining envelope cables. The pilot reported that he also cut several envelope cables "to make sure that the basket was isolated from the transmission wires." Rescue personnel began removing the basket's occupants, and tending to their medical needs.

PERSONNEL INFORMATION

According to FAA records, the pilot received his commercial pilot certificate on September 7, 1994. The pilot reported on the NTSB's Pilot/Operator Aircraft Accident Report Form 6120.1/2 that he had completed his required FAA Part 61 flight review on September 14, 1997, and that he had accumulated 402 hours of flight experience by the time of the accident. He further documented that he had flown 18 hours during the last 90 days, and had two commercial flights at or near maximum gross weight in the previous 48 hours.

BALLOON INFORMATION

The balloon was a 250,000 cubic foot (known as an A-250), propane heated, hot-air balloon, which was manufactured by Cameron Balloons US, in 1993. It was certificated for a maximum gross takeoff weight of 4,200 pounds (Cameron Balloons US, in 1995, certificated the A-250 model for 5,000 pounds). The envelope's weight was 491 pounds; the three burners weighed 98 pounds; the basket weighed 584 pounds; the six tanks weighed 342 pounds; the 90 gallons of fuel weighed 381 pounds. These components added up to 1,896 pounds, which allowed 2,304 for the pilot, passengers, and miscellaneous baggage.

The balloon was equipped with a mode-C transponder, which permitted FAA air traffic control personnel to track its movement. The pilot also had a global positioning system (GPS) receiver on board which provided him with airspeed and direction of flight. The basket was connected to the burner unit by 4 stainless steel suspension cables, and the burner unit was connected to the envelope by 20 Kevlar envelope cables.

The balloon was equipped with an air temperature sensing unit, located approximately 2/3 of the way up inside the envelope. A pyrometer wire (thermistor cable) ran down the front interior of the envelope, and connected to an envelope temperature gauge in the pilot's section of the basket.

METEROROLOGICAL CONDITIONS

At 0856, the weather conditions at the Albuquerque International Airport (elevtion 5,352 feet), Albuquerque, New Mexico, were as follows: wind 330 degrees for 10 knots; visibility 10 statue miles; clear of clouds; temperature 48 degrees F.; dew point 19 degrees F.; altimeter 30.07 inches of mercury. An upper air sounding plot taken at 0600 on October 4, 1999, indicated that the surface wind was 350 degrees for 12 knots, and at approximately 10,000 msl the wind was 300 degrees for 27 knots. Another balloon pilot, who landed about 100 yards from the accident balloon approximately 10 to 15 minutes after the accident, said that his GPS had indicated wind gusts to 22 knots just minutes before landing. This pilot could not remember how high above the ground that he made the observation.

A pilot of another commercial flight reported departing Balloon Fiesta Park at 0800 with 5 to 6 knot winds. He said that after 45 minutes of flight and traveling approximately 120 degrees at 10 to 12 knots, he began to descend for a landing. At approximately 150 feet above ground level (agl) he experienced a severe wind shear forcing him south and into the ground. He estimated the wind to be 175 degrees at 20 to 25 knots. He reported making three attempts to land, and aborted each of them. At 0900, he made an uneventful landing near Interstate-40 and Tramway Blvd (elevation 5,700 feet, 080 degrees at 4.75 statute miles from the accident site).

WRECKAGE AND IMPACT INFORMATION

The balloon came to rest between Wyoming Blvd. and Pennsylvania St. approximately 55 feet north of Ordnance Rd. on KAFB (N35 degrees 02.432 minutes, W106 degrees 33.205 minutes - see attached location maps). Part of the balloon's envelope was found draped over an east-west transmission wire, and the remainder of the envelope was found on the south side of the wires. The basket was found with its front side facing approximately north (the reverse direction of travel), and oriented upright. There was no identifiable ground scar, suggesting that the basket had fallen vertically down.

The basket's left front padded corner had approximately two feet of material and foam missing. The wicker below this corner had been cut in two places to form a hatch like door (it was determined that the rescue personnel had cut this). The right front stainless steel suspension cable had material missing from it (approximately 1/3 of the way through the steel cable) which suggested that it had been heavily abraded. Approximately 12 of the Kevlar envelope cables were separated in a frayed appearance (see photograph). The remaining approximate 8 Kevlar envelope cables had separated in a clean cut appearing manner, which suggested that a knife had cut them.

A circuit board in the pilot's instrument gauges (temperature and altimeter) was found blackened and melted from what appeared to be a short circuit. The pyrometer wire had an estimated 10 foot section which was melted and burned. The temperature sensor unit in the upper part of the envelope had one transistor melted and fragmented. The envelope temperature safety/maintenance tab (four dots which blacken at 225 degrees, 250 degrees, 275 degrees, and 300 degrees) located 3/4 of the way up the envelope were blackened through 275 degrees Fahrenheit (the pilot reported that a normal flight started with an envelope temperature of 195 degrees, and finishing at 200 degrees).

MEDICAL AND PATHOLOGICAL INFORMATION

Toxicology tests were performed on the pilot by the FAA's Civil Aeromedical Institute (CAMI) in Oklahoma City, Oklahoma. According to CAMI's report (#9800278001), the pilot's blood was tested, and the tests for carbon monoxide, cyanide, volatiles, and drugs were all negative.

TEST AND RESEARCH

The first transmission wire that the balloon impacted was located at N35 degrees 02.874 minutes, W106 degrees 33.863 minutes (see attached diagrams). The New Mexico Public Service Company reported that the circuit on this wire was broken at 0908. The wire was .666 inches in diameter, and located 30 feet above the ground. The upper most static line was 15 feet higher.

The distance from the first wire impact to second wire impact was 4,300 feet in a direct line. According to witness statements and the pilot's statement, the balloon traveled east immediately after the first wire impact, and then south for an estimated distance of 6,000 feet. The second wire was .666 inches in diameter and located 28 feet above the ground. The New Mexico Public Service Company reported that the power had been shut off in this wire prior to the balloon's impact.

Photographs taken prior to the second impact indicate that balloon's scoop was partially missing. One hole could be seen in the envelope, which was just above the envelope's throat and was approximately 5 to 8 feet in diameter.

Radar data and the New Mexico Public Service Company information suggests that 3 to 4 minutes elapsed between the first and second wire impacts. The radar data further indicates that the balloon lost approximately 550 feet during the last minute of flight. An active balloon flight instructor and a balloon FAA Designated Examiner both stated that during a landing approach where wires are present, the wires should be crossed in level flight or ascending flight.

The balloon's FAA approved Balloon Flight Manual, in Section 3 - Emergency Procedures, states "if contact with electric power lines becomes inevitable: Pull the parachute or rip line to ensure that the basket is as close to the ground as possible before contact."

According to three articles that are attached, a wind shear may effect the lifting capabilities of an envelope by four possible scenarios: False lift, diminished capacity of envelope from being "struck" by a force, low level jet stream pulling air out of the balloon, and false heavy. According to the articles, if a balloon descends through a wind shear to an air mass with a slower velocity, the faster moving air flowing over the spherical top will create lift (Bernoulli's Principal). The pilot who wants to descend through this wind shear will have to allow his envelope to cool an additional amount to maintain a descent. At the moment, the balloon fully transitions to the lower air mass, the wind generated lift ceases, and the balloon's rate of descent incrementally increases.

ADDITIONAL DATA

The balloon, including all components and logbooks, was released to the pilot's wife on October 5, 1998.

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