NTSB Factual Report

On June 8, 2013 at 0750 mountain daylight time, an Ultramagic M-105 hot air balloon, N30018, impacted in an undeveloped industrial park during a high wind landing near Louisville, Colorado. The commercial pilot and 4 passengers on board were not uninjured, and the balloon sustained minor damage. The balloon was owned and operated by a private individual under the provisions of 14 CFR Part 91 as a business flight. Visual meteorological conditions prevailed at the time of the flight, which operated without a flight plan. The flight originated from Gunbarrel, Colorado, about 0700.

The pilot reported he took off around the same time several other ride balloons that were flying that day took off. He said that he received the same weather forecast the other pilots received. The weather was nice. There were no concerns. "It was a typical ride balloon day." The pilot said that about half an hour into the flight the wind began picking up. He got into the landing mode. He said at that point the first good field he could put down in he was taking it. He briefed the passengers that when they hit the ground the balloon would tip over and drag to a stop. Everyone was ready. The pilot said that at altitude, looking at the surface, he couldn't discern what the winds were doing. Where he was at, the balloon was heading northeasterly, which is the direction he wanted to go. However, as they got closer to the surface, the wind started taking them south, then southeast. The pilot said he took the balloon back up to 1,500 feet agl so that he could drift more toward the southeast. He then started hunting for a good spot to touchdown. "For me it was the direction. I could see where the others were going and I didn't want to go that way."

The pilot determined he'd land in a field on the north side of a highway. At first, he didn't think he'd make the field as it was a long way off, and the wind was actually now taking them around to the north. However as they reached the north end of the field, the wind caused the balloon's path to curve around bringing them right back to it. "We were going to take it." The pilot said on coming in to land he could feel cold air coming into his face. The balloon was accelerating. The pilot leveled off about 10 feet above the ground and then opened up the top of the envelope. He said they hit the ground pretty solid, stuck there, and dragged. He said they were dragged about 100 feet before stopping. After they were stopped, he got everyone out and checked them. Everyone was alright.

The National Weather Service (NWS) Surface Analysis Chart at 0600 MDT depicted a low pressure system over North Dakota with an associated occluded front al system extending from the low south-southeast to another low pressure system over South Dakota where the triple point of the front was located. There it split into a warn front to the southeast and a cold front to the southwest across Nebraska and northern Colorado, and then west-northwest back into Wyoming. Two high pressure systems were located over western Colorado and two low pressure systems were located over eastern Colorado with a trough of low pressure extending between the lows into New Mexico. The resultant pressure systems created a light westerly wind component over the region with wind speeds of 10 knots or less, with the cold front oriented in an east-to-west direction over northern Colorado south of the cold front.

The station model for Denver International Airport depicted a wind from the west-southwest at approximately 10 knots. The station model for Cheyenne, Wyoming, 78 miles north of Denver depicted a northerly wind sustained at approximately 25 knots. Several stations over Wyoming and Nebraska behind the cold front depicted northerly winds at 15 to 20 knots.

At 0900, the low pressure system over South Dakota became the primary system with the cold front extending south-southwestward across Nebraska and into central Colorado. The station model for Denver depicted a wind from the north at 15 knots. Several other stations in northeast Colorado depicted northerly winds sustained at 15 to 35 knots, with stations south of the front reporting westerly winds at 10 knots or less.

At 0655, the routine aviation weather report (METAR) for the Erie Airport (KEIK), 11 miles northeast of the accident site, was wind 300 degrees at 4 knots, clear skies, visibility 10 miles, temperature 68 degrees Fahrenheit (F), dew point 43 degrees F, and altimeter 29.81 inches.

At 0755, KEIK METAR reported wind 030 degrees at 16 knots, gusts to 24 knots, clear skies, visibility 10 miles, temperature 65 degrees F, dew point, 47 degrees F, and altimeter 29.89 inches.

The first weather observation for the area that indicated a frontal passage was at Cheyenne Regional Airport, Wyoming. At 0453, automated wind was reported as 270 degrees at 9 knots. At 0549 the automated wind was from 350 degrees at 23 knots gusting to 38 knots.

Wind conditions at Fort Collins-Loveland Municipal Airport, 38 miles north of Denver, at 0635 were calm. At 0655 when the front passed through, the wind was 020 degrees at 13 knots gusting to 25 knots. By 0815, the wind was gusting to 35 knots.

The front moved through Denver International Airport at 0744, when a squall or sudden increase in wind speed was reported from 020 degrees at 24 knots gusting to 34 knots. Wind gusts would continue for the next few hours with gusts of 36 knots reported at 0753 and gusts of 24 knots at 0853.

The front continues to south reaching Front Range Airport, 19 miles east of Denver, at 0755 and Centennial Airport, 15 miles southeast of Denver, at 0834 and producing gusts to 30 and 35 knots respectively.

The Denver upper air sounding or rawinsonde observation at 0800 depicted a surface-based temperature inversion due to radiational cooling from the surface to approximately 500 feet agl with light winds below and winds from the west immediately above the inversion through 10,000 feet and veering to the northwest with wind speeds increasing with height. A low-level wind maximum was identified at 7,000 feet from 270 degrees at 30 knots. A mean 18,000 feet wind was from 308 degrees at 31 knots, and the level of maximum wind at 35,000 feet was from 330 degrees at 80 knots. The sounding depicted a stable atmosphere with a Lifted Index of 5. The lifted condensation level wat identified at 5,055 feet agl with a convective condensation level at 12,226 feet agl. The equilibrium level or expected top of convective clouds was at 37,000 feet. The freezing level was identified at approximately 14,801 feet.

The sounding wind and temperature profile supported mountain wave conditions with waves at 12,000, 15,000, and 19,000 feet.

The NWS Terminal Aerodrome Forecast (TAF) was issued by the Denver/Boulder Weather Service Forecast Office located in Boulder, Colorado. The TAF for Denver International Airport during the period in which the accident took place were as follows:

Denver Terminal Area Forecast, July 8, 2013 at 1139 UTC (0539 MDT,) wind 210 degrees at 13 knots, visibility more than 6 statute miles, few clouds at 8,000 feet mean sea level (MSL), scattered clouds at 12,000 feet MSL

From 0800, wind 310 degrees at 11 knots, visibility more than 6 statute miles, few clouds at 8,000 feet MSL

From 1000, wind 020 degrees at 13 knots, gusts to 23 knots, visibility more than 6 statute miles, few clouds at 8,000 feet MSL

From 1700, wind 060 degrees at 13 knots, visibility more than 6 statute miles, few clouds at 8,000 feet MSL, broken ceiling at 15,000 feet MSL

From 2000, wind 140 degrees at 5 knots, visibility more than 6 statute miles, few clouds at 8,000 feet MSL

From 0000 on June 9, 2013, wind 200 degrees at 7 knots, visibility more than 6 statute miles, few clouds at 10,000 feet MSL

From 0700 on June 9, 2013, wind 270 degrees at 5 knots, visibility more than 6 statute miles, few clouds at 10,000 feet MSL

An amended TAF was issued for KDEN at 0652, with forecast wind 210 degrees at 13 knots, visibility more than 6 statute miles, few clouds at 8,000 feet MSL, scattered clouds at 12,000 feet MSL, and scattered clouds at 22,000 feet MSL

From 0830, wind 010 degrees at 18 knots, gusts to 30 knots, visibility more than 6 statute miles, scattered clouds at 8,000 feet MSL, scattered clouds at 12,000 feet MSL

From 1300, wind 020 degrees at 15 knots, gusts to 25 knots, visibility more than 6 statute miles, scattered clouds at 8,000 feet MSL, scattered clouds at 12,000 feet MSL

From 1600, wind 060 degrees at 13 knots, visibility more than 6 statute miles, scattered clouds at 8,000 feet MSL, and broken ceiling at 15,000 feet MSL

From 2000, wind 140 at 5 knots, visibility more than 6 statute miles, scattered clouds at 8,000 feet MSL

From 0000 on June 9, 2013, wind 200 degrees at 7 knots, visibility more than 6 statute miles, few clouds at 10,000 feet MSL

From 0700 on June 9, 2013, wind 270 degrees at 5 knots, visibility more than 6 statute miles, few clouds at 10,000 feet MSL

The TAF issued at 0539 expected VMC conditions to prevail with a wind from the southwest or 210 degrees at 13 knots shifting northwest or 310 degrees at 11 knots at 0800. After 1000 through 1700, the wind was expected from the north at 020 degrees at 13 knots with gusts to 23 knots.

The forecast was amended at 0652 with the primary change being the wind shift occurring at 0830 with the wind from the north or 010 degrees at 18 knots gusting to 30 knots, with gusts continuing through 1700.

According to NWS forecast directives, the decision to amend the TAF relies on the forecaster's assessment of existing conditions and expectations. If the conditions change earlier or later than forecast, but the TAF shows the expected trend and will soon recover, an amendment may not be needed. Small fluctuation in the observed conditions should not result in a minor adjustment to the TAF, unless an improving weather conditions occur sooner than forecast, then an amended TAF is necessary. The prevailing wind direction will be forecast for any speed greater than or equal to 7 knots. The TAF should be amended if the mean wind direction differs by 30 degrees or more with a mean wind speed greater than or equal to 12 knots, or the forecast/actual mean wind speed differ more than (or equal to) 10 knots and the mean wind is expected to be greater than or equal to 12 knots.

A review of the NWS forecast discussion issued 0430 indicated that the cold front was expected to drop across Colorado during the middle of the day and that the NWS aviation forecaster was expecting a wind shift to the west-northwest during the morning and then north to northeast with the passage of the front before 1200, with wind gusts possible in the 20 to 30 knot range for a couple of hours behind the front. No weather warnings or high wind advisories were in effect during the period.

The area forecast is a forecast of VFR clouds and weather conditions over an area the size of several states. The Salt Lake City regional forecast was issued at 0445 and was valid through 1700. The synoptic section discussed a moderately strong northwesterly jet stream over the region with a surface cold front moving eastward through the region. The forecast for the northern plains expected scattered high cirrus clouds with no obstructions to visibility. Northwesterly winds of 20 knots gusting to 30 knots were expected over Wyoming, but there was no mention of wind in the forecast for Colorado. NWS guidelines require a forecaster to include wind information whenever winds of 20 knots or more are expected.

During the period the NWS had no Severe Weather Forecast Alerts, Convective SIGMETs (Significant Meteorological Information), SIGMETs, or Center Weather Advisories for high winds over Colorado outside of thunderstorm activity. AIRMET (Airmen's Meteorological Information) TANGO was in effect for Montana, Wyoming, and Colorado, for moderate turbulence between flight levels 280 and 380, and an advisory for low-level turbulence over Wyoming. The Denver Center Weather Service Unit did not issue any Center Weather Advisories for high winds or squalls impacting the area.

The pilot stated that after the flight he got together with one of the other balloon pilots who flew that day to discuss what happened to them. He said they both agreed that something was missing in the forecast.

NTSB Probable Cause

The balloon's encounter with unforecast strong gusting wind, which resulted in a high-wind landing. Contributing to the accident was the National Weather Service's misjudgment of the timing and underestimation of the magnitude of the frontal boundary moving across the region.