Narrative:

Forecasted surface and winds aloft information was obtained 2 hours prior to planned flight. This information was used for a flight plan/profile for hot air balloons. Prior to launch this information was confirmed by use of a pibal. The planned flight was to utilize the winds to keep the balloons in the green river valley near auburn, washington. The flight of 3 balloons launched from a large field in south auburn. After approximately 1 hour of flight the balloons, still in the vicinity of one another, attempted to utilize the forecasted northwest winds aloft to fly to large open area for final landing. While using the winds to navigation, the direction changed to a more easterly flow. This carried the balloons to an area with smaller potential landing sites. In my case, the change occurred while crossing a major pwrline which ran east/west. The new wind direction was to the east along the pwrline. Because of the class B airspace restr above, I was unable to attempt finding a more favorable wind at higher altitudes. With the pwrline below, it was unsafe to descend near them. Further, wind indicators on the ground did not show a different direction. After several mi and 30 mins of additional flight, the balloon flight path and the pwrline diverged allowing more maneuvering room below. By this time the balloon was over heavily wooded and residential areas. As the flight continued, the wind continued to slow. After a 2 hour and 15 min flight the balloon had approximately 30 mins of fuel remaining. The decision was made to land the balloon in a residential subdivision with assistance from the ground crew. The balloon landed on the edge of the subdivision, was walked to a nearby cul-de-sac and deflated. Inaccurate information of the winds aloft forecast for balloon activity can often be attributed to the age of the information. In this case, the readings for the forecast winds aloft were taken some 12 hours before the flight. It was the most current information available. Forecasted winds are often unreliable information for balloon flight. First, because of the age of the information relative to balloon activity which is conducted at sunrise and sunset. The information is often as much as 12 hours old. Second, the forecast does not consider the boundary layer in which most balloon flight occurs and which winds are essential for landing. Third, forecast surface winds are often not made if they are anticipated to be below 10 KTS. Although balloons would not fly into forecast surface stronger than this, it is helpful to know what the forecast wind direction will be on the surface. The balloonists are in a unique position to study the winds as they fly and to get current information as conditions change from indicators of speed and direction on the ground. Aloft they can test the speed and direction by going up and down in altitude. Still, planned flight profiles are based on information available at takeoff. The age and accuracy of forecasts of winds does not often provide a valuable service. Changing wind conditions do not happen suddenly. The dynamics of airflow develop over a course of time. That length of time will vary, but can still be predicted. More frequent readings with which to make forecast would be helpful. Perhaps the most beneficial tool in the future would be the wind profiler using doppler radar. This would allow for more current and accurate information in flight planning. In this case, meteorological conditions changed the planned course and resulted in terminating the flight in a residential area. Although the flight could have been continued, there was no assurance that a more suitable area to land was obtainable. Safety of those in the air and ground were considered in choosing the landing site.

Related reports:

Google
 

Original NASA ASRS Text

Title: A HOT AIR BALLOON LANDED IN A RESIDENTIAL AREA.

Narrative: FORECASTED SURFACE AND WINDS ALOFT INFO WAS OBTAINED 2 HRS PRIOR TO PLANNED FLT. THIS INFO WAS USED FOR A FLT PLAN/PROFILE FOR HOT AIR BALLOONS. PRIOR TO LAUNCH THIS INFO WAS CONFIRMED BY USE OF A PIBAL. THE PLANNED FLT WAS TO UTILIZE THE WINDS TO KEEP THE BALLOONS IN THE GREEN RIVER VALLEY NEAR AUBURN, WASHINGTON. THE FLT OF 3 BALLOONS LAUNCHED FROM A LARGE FIELD IN S AUBURN. AFTER APPROX 1 HR OF FLT THE BALLOONS, STILL IN THE VICINITY OF ONE ANOTHER, ATTEMPTED TO UTILIZE THE FORECASTED NW WINDS ALOFT TO FLY TO LARGE OPEN AREA FOR FINAL LNDG. WHILE USING THE WINDS TO NAV, THE DIRECTION CHANGED TO A MORE EASTERLY FLOW. THIS CARRIED THE BALLOONS TO AN AREA WITH SMALLER POTENTIAL LNDG SITES. IN MY CASE, THE CHANGE OCCURRED WHILE XING A MAJOR PWRLINE WHICH RAN E/W. THE NEW WIND DIRECTION WAS TO THE E ALONG THE PWRLINE. BECAUSE OF THE CLASS B AIRSPACE RESTR ABOVE, I WAS UNABLE TO ATTEMPT FINDING A MORE FAVORABLE WIND AT HIGHER ALTS. WITH THE PWRLINE BELOW, IT WAS UNSAFE TO DSND NEAR THEM. FURTHER, WIND INDICATORS ON THE GND DID NOT SHOW A DIFFERENT DIRECTION. AFTER SEVERAL MI AND 30 MINS OF ADDITIONAL FLT, THE BALLOON FLT PATH AND THE PWRLINE DIVERGED ALLOWING MORE MANEUVERING ROOM BELOW. BY THIS TIME THE BALLOON WAS OVER HEAVILY WOODED AND RESIDENTIAL AREAS. AS THE FLT CONTINUED, THE WIND CONTINUED TO SLOW. AFTER A 2 HR AND 15 MIN FLT THE BALLOON HAD APPROX 30 MINS OF FUEL REMAINING. THE DECISION WAS MADE TO LAND THE BALLOON IN A RESIDENTIAL SUBDIVISION WITH ASSISTANCE FROM THE GND CREW. THE BALLOON LANDED ON THE EDGE OF THE SUBDIVISION, WAS WALKED TO A NEARBY CUL-DE-SAC AND DEFLATED. INACCURATE INFO OF THE WINDS ALOFT FORECAST FOR BALLOON ACTIVITY CAN OFTEN BE ATTRIBUTED TO THE AGE OF THE INFO. IN THIS CASE, THE READINGS FOR THE FORECAST WINDS ALOFT WERE TAKEN SOME 12 HRS BEFORE THE FLT. IT WAS THE MOST CURRENT INFO AVAILABLE. FORECASTED WINDS ARE OFTEN UNRELIABLE INFO FOR BALLOON FLT. FIRST, BECAUSE OF THE AGE OF THE INFO RELATIVE TO BALLOON ACTIVITY WHICH IS CONDUCTED AT SUNRISE AND SUNSET. THE INFO IS OFTEN AS MUCH AS 12 HRS OLD. SECOND, THE FORECAST DOES NOT CONSIDER THE BOUNDARY LAYER IN WHICH MOST BALLOON FLT OCCURS AND WHICH WINDS ARE ESSENTIAL FOR LNDG. THIRD, FORECAST SURFACE WINDS ARE OFTEN NOT MADE IF THEY ARE ANTICIPATED TO BE BELOW 10 KTS. ALTHOUGH BALLOONS WOULD NOT FLY INTO FORECAST SURFACE STRONGER THAN THIS, IT IS HELPFUL TO KNOW WHAT THE FORECAST WIND DIRECTION WILL BE ON THE SURFACE. THE BALLOONISTS ARE IN A UNIQUE POS TO STUDY THE WINDS AS THEY FLY AND TO GET CURRENT INFO AS CONDITIONS CHANGE FROM INDICATORS OF SPD AND DIRECTION ON THE GND. ALOFT THEY CAN TEST THE SPD AND DIRECTION BY GOING UP AND DOWN IN ALT. STILL, PLANNED FLT PROFILES ARE BASED ON INFO AVAILABLE AT TKOF. THE AGE AND ACCURACY OF FORECASTS OF WINDS DOES NOT OFTEN PROVIDE A VALUABLE SVC. CHANGING WIND CONDITIONS DO NOT HAPPEN SUDDENLY. THE DYNAMICS OF AIRFLOW DEVELOP OVER A COURSE OF TIME. THAT LENGTH OF TIME WILL VARY, BUT CAN STILL BE PREDICTED. MORE FREQUENT READINGS WITH WHICH TO MAKE FORECAST WOULD BE HELPFUL. PERHAPS THE MOST BENEFICIAL TOOL IN THE FUTURE WOULD BE THE WIND PROFILER USING DOPPLER RADAR. THIS WOULD ALLOW FOR MORE CURRENT AND ACCURATE INFO IN FLT PLANNING. IN THIS CASE, METEOROLOGICAL CONDITIONS CHANGED THE PLANNED COURSE AND RESULTED IN TERMINATING THE FLT IN A RESIDENTIAL AREA. ALTHOUGH THE FLT COULD HAVE BEEN CONTINUED, THERE WAS NO ASSURANCE THAT A MORE SUITABLE AREA TO LAND WAS OBTAINABLE. SAFETY OF THOSE IN THE AIR AND GND WERE CONSIDERED IN CHOOSING THE LNDG SITE.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.