Accident Overview
On June 8, 2013, at 0854 mountain daylight time, an Ultramagic T210 hot air balloon, registration N201FW, impacted open terrain during a high wind landing near Boulder, Colorado. Two passengers sustained minor injuries; the commercial pilot and the other nine passengers were uninjured. The balloon received minor damage. The balloon was registered to Fair Winds, Incorporated and operated under 14 CFR Part 91 as a business flight. Visual meteorological conditions prevailed, and the flight operated without a flight plan. The flight had originated from Gunbarrel, Colorado, at approximately 0715.
Flight and Weather Conditions
The pilot reported checking the weather forecast and receiving a briefing from Flight Service before the flight. He consulted with other balloon pilots flying that day, and they collectively determined conditions were suitable. Weather was good at takeoff. About 45 minutes into the flight, at 3,000 feet above ground level, the pilot noticed other balloons in the vicinity were "screaming up and down." Within five minutes, the wind, previously easterly at 6 to 8 knots, shifted to southwesterly at 30 knots or more. The balloon began bouncing, and the wind did not abate, prompting the pilot to land immediately.
The pilot briefed passengers for a high wind landing and directed them to the bottom of the basket. He descended to find a suitable landing area, leveled over a lake, and flew over a swell. Observing that he was heading toward a windmill farm, he pulled the vent line and touched down in a conservation area. Wind speed was approximately 31 to 32 miles per hour. The basket tipped and began dragging for about 50 to 60 yards. A gust then lifted the balloon about five feet, but the pilot continued pulling the top vent, returning the balloon to the ground where it stopped.
Weather Analysis
The National Weather Service Surface Analysis Chart at 0600 MDT showed a low pressure system over North Dakota with an associated occluded front extending to another low over South Dakota, where the front split into a warm front to the southeast and a cold front to the southwest across Nebraska and northern Colorado. Two high pressure systems were over western Colorado, and two lows over eastern Colorado with a trough extending into New Mexico. This pattern created a light westerly wind component with speeds 10 knots or less, with the cold front oriented east-to-west over northern Colorado.
Station models indicated variable conditions: Denver International Airport reported west-southwest winds at about 10 knots, while Cheyenne, Wyoming, reported northerly winds at about 25 knots. By 0900, the cold front extended south-southwest across Nebraska into central Colorado, with Denver reporting north winds at 15 knots and other stations in northeast Colorado reporting northerly winds of 15 to 35 knots. Stations south of the front reported westerly winds of 10 knots or less.
Surface observations at Erie, Colorado (KEIK), 12 miles east-northeast of the accident, showed wind at 0655 from 300 degrees at 4 knots, and at 0855 from 020 degrees at 14 knots gusting to 22 knots. The first indication of a frontal passage was at Cheyenne Regional Airport, Wyoming, where wind shifted from 270 degrees at 9 knots at 0453 to 350 degrees at 23 knots gusting to 38 knots at 0549. At Fort Collins-Loveland Municipal Airport, wind was calm at 0635, then shifted to 020 degrees at 13 knots gusting to 25 knots by 0655, with gusts to 35 knots by 0815. The front passed Denver International Airport at 0744 with a squall from 020 degrees at 24 knots gusting to 34 knots, with continued gusts. Upper air sounding at 0800 showed a surface-based temperature inversion, light winds below, and increasing westerly winds aloft, with a low-level wind maximum at 7,000 feet from 270 degrees at 30 knots. The sounding supported mountain wave conditions.
Terminal Aerodrome Forecasts (TAF) and amendments predicted wind shifts. The TAF issued at 0539 expected southwest winds shifting northwest, then north with gusts. An amended TAF at 0652 shifted the wind change to 0830 with north winds at 18 knots gusting to 30 knots. NWS forecast discussion at 0430 indicated the cold front was expected to drop across Colorado during the middle of the day, with wind gusts possible in the 20 to 30 knot range. No warnings or high wind advisories were in effect. The Salt Lake City regional forecast mentioned northwesterly winds of 20 knots gusting to 30 knots over Wyoming but did not specify winds for Colorado, contrary to NWS guidelines for winds of 20 knots or more. No SIGMETs or Center Weather Advisories for high winds were issued.
After the incident, the pilot met with other pilots who had been flying and learned that a frontal boundary wind from thunderstorms over Nebraska had brought 30-knot north-northeast winds into the area. The pilot remarked that his company prides itself on weather planning and that if conditions are marginal, they do not fly, adding that the National Weather Service "missed this one." The high winds continued for about an hour and a half after landing.