Narrative:

We were put on a weather hold until xa:00. My student pilot asked me if we would fly and I said it depended on what happened when the sun mixed out. The last two mornings were similar and we had flown. At home; probably not; due to the temperature dew point being the same and typically when the sun rose and mixed with the dense atmosphere we would be socked in. However; having spoken to [event] organizers the two previous days; they said fog typically does not form in this area. At the xa:00 weather briefing winds were less than 8 mph and visibility was greater than 5 miles. I pulled [the latest] taf from the ballooncast internet site. Taf indicated mist and low visibilities for the area and light winds; with increasing speeds above single digits aloft. A fly in task was called by the organizers. I had student pilot call the AWOS; which reported 5 miles visibility - pressure rising. We loaded up and off we went. We spent about 20 minutes finding a launch site. A handful of balloons had chosen the same site. Once again; I had student pilot call the AWOS; which reported 4 miles visibility and mist. We began to unload. Several balloons were now in the air and all the balloons in the field were inflating as we were setting up our balloons. I was carrying two crew members who had flown previously several times just this week. I began approximately a 300 FPM ascent with a bearing of 270 degrees (away from target area). I wanted to attain altitude fairly quickly to find the layer of wind with a bearing of about 40 degrees or less. I knew this was around 400 ft based on previous pibal readings. After 2 minutes I reached an altitude of 400 ft AGL and forward movement had stopped. We began going 'backwards' with a bearing of 40 degrees. I used my turning vent to turn around or 'spin' the balloon and that is when I saw only about 4 balloons in the air and a thick blanket of fog heading toward me. I knew I had seen many more than 4 balloons flying when I was setting up. I vented to level out and assess the situation. I could not land as I was passing over the road. Looking down I noticed a balloon passing back over the road with a bearing perfect to land in the field I had just taken off from. I burned to increase altitude so I could line up to go back down and land in the field I took off from. Once lined up I vented to descend and hoped I would go down and get the same wind direction the previous balloon had. I instructed my passengers to help look for any obstacles. I also hooked up the drop line in case it could help. I prepared passengers for a possible hard landing; in case our direction changed. As I crossed over the road; I vented to continue descent into the same field I had launched in. Due to the close proximity of a fence line I chose to throw the drop line. I landed with one small bounce as crew had grabbed the drop line. Winds were 6 mph upon landing. Total flight duration 11 minutes.

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Original NASA ASRS Text

Title: Balloon pilot reports sighting fog moving in shortly after lift off requiring an immediate descent and return to the departure field.

Narrative: We were put on a weather hold until XA:00. My student pilot asked me if we would fly and I said it depended on what happened when the sun mixed out. The last two mornings were similar and we had flown. At home; probably not; due to the temperature dew point being the same and typically when the sun rose and mixed with the dense atmosphere we would be socked in. However; having spoken to [event] organizers the two previous days; they said fog typically does not form in this area. At the XA:00 weather briefing winds were less than 8 MPH and visibility was greater than 5 miles. I pulled [the latest] TAF from the Ballooncast Internet site. TAF indicated mist and low visibilities for the area and light winds; with increasing speeds above single digits aloft. A fly in task was called by the organizers. I had student pilot call the AWOS; which reported 5 miles visibility - pressure rising. We loaded up and off we went. We spent about 20 minutes finding a launch site. A handful of balloons had chosen the same site. Once again; I had student pilot call the AWOS; which reported 4 miles visibility and mist. We began to unload. Several balloons were now in the air and all the balloons in the field were inflating as we were setting up our balloons. I was carrying two crew members who had flown previously several times just this week. I began approximately a 300 FPM ascent with a bearing of 270 degrees (away from target area). I wanted to attain altitude fairly quickly to find the layer of wind with a bearing of about 40 degrees or less. I knew this was around 400 FT based on previous pibal readings. After 2 minutes I reached an altitude of 400 FT AGL and forward movement had stopped. We began going 'backwards' with a bearing of 40 degrees. I used my turning vent to turn around or 'spin' the balloon and that is when I saw only about 4 balloons in the air and a thick blanket of fog heading toward me. I knew I had seen many more than 4 balloons flying when I was setting up. I vented to level out and assess the situation. I could not land as I was passing over the road. Looking down I noticed a balloon passing back over the road with a bearing perfect to land in the field I had just taken off from. I burned to increase altitude so I could line up to go back down and land in the field I took off from. Once lined up I vented to descend and hoped I would go down and get the same wind direction the previous balloon had. I instructed my passengers to help look for any obstacles. I also hooked up the drop line in case it could help. I prepared passengers for a possible hard landing; in case our direction changed. As I crossed over the road; I vented to continue descent into the same field I had launched in. Due to the close proximity of a fence line I chose to throw the drop line. I landed with one small bounce as crew had grabbed the drop line. Winds were 6 MPH upon landing. Total flight duration 11 minutes.

Data retrieved from NASA's ASRS site as of April 2012 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.