Hot air balloon pilot gets wrapped up in the mist.

Attributes
ACN	157049
Time
Date	199009
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : ca72
State Reference	CA
Altitude	agl bound lower : 0 agl bound upper : 1000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	general aviation : corporate
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	climbout : intermediate altitude cruise other descent other
Flight Plan	None
Person 1
Affiliation	Other
Function	flight crew : captain oversight : pic
Qualification	pilot : commercial
Experience	flight time last 90 days : 60 flight time total : 4040 flight time type : 200
ASRS Report	157049
Person 2
Affiliation	government : faa
Function	other personnel other
Qualification	other
Events
Anomaly	inflight encounter : vfr in imc inflight encounter : weather non adherence : far
Independent Detector	other flight crewa
Resolutory Action	flight crew : exited adverse environment
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

After a complete WX briefing from oak FSS, which did indicate the possibility of IFR conditions on the coast, I prepared for a XA00 am departure from the town of yountville. Conditions locally were clear, calm and approximately 20 mi visibility. After takeoff a fog bank could be seen at the south end of the napa valley at the san pablo bay (approximately 18 mi away). This is not unusual circumstance. By XA30 am PDT the fog bank had rapidly moved up the napa valley, forming underneath my aircraft in a layer from approximately 700-900' AGL (about 200' thick). I descended through a small hole in the fog, coming out at approximately 700' AGL (800' MSL). I could see the surface through the hole throughout my descent. After coming down through the cloud layer, I initiated a full stop, full deflation landing. At no time were my aircraft or passenger in danger (the airspace is uncontrolled and there are no IFR approachs at that part of napa valley). I feel the 1 mi visibility requirement may have been compromised as I descended through the hole in the fog for about 30 seconds. I feel it would be beneficial to have a dewpoint measuring INS available close to our flight area because the values obtained from the reporting stations available to us in the early morning are usually influenced by the san francisco/san pablo/richardson bay and are not always reflections of our more inland launch site.

Original NASA ASRS Text

Title: HOT AIR BALLOON PLT GETS WRAPPED UP IN THE MIST.

Narrative: AFTER A COMPLETE WX BRIEFING FROM OAK FSS, WHICH DID INDICATE THE POSSIBILITY OF IFR CONDITIONS ON THE COAST, I PREPARED FOR A XA00 AM DEP FROM THE TOWN OF YOUNTVILLE. CONDITIONS LOCALLY WERE CLR, CALM AND APPROX 20 MI VISIBILITY. AFTER TKOF A FOG BANK COULD BE SEEN AT THE S END OF THE NAPA VALLEY AT THE SAN PABLO BAY (APPROX 18 MI AWAY). THIS IS NOT UNUSUAL CIRCUMSTANCE. BY XA30 AM PDT THE FOG BANK HAD RAPIDLY MOVED UP THE NAPA VALLEY, FORMING UNDERNEATH MY ACFT IN A LAYER FROM APPROX 700-900' AGL (ABOUT 200' THICK). I DSNDED THROUGH A SMALL HOLE IN THE FOG, COMING OUT AT APPROX 700' AGL (800' MSL). I COULD SEE THE SURFACE THROUGH THE HOLE THROUGHOUT MY DSNT. AFTER COMING DOWN THROUGH THE CLOUD LAYER, I INITIATED A FULL STOP, FULL DEFLATION LNDG. AT NO TIME WERE MY ACFT OR PAX IN DANGER (THE AIRSPACE IS UNCONTROLLED AND THERE ARE NO IFR APCHS AT THAT PART OF NAPA VALLEY). I FEEL THE 1 MI VISIBILITY REQUIREMENT MAY HAVE BEEN COMPROMISED AS I DSNDED THROUGH THE HOLE IN THE FOG FOR ABOUT 30 SECS. I FEEL IT WOULD BE BENEFICIAL TO HAVE A DEWPOINT MEASURING INS AVAILABLE CLOSE TO OUR FLT AREA BECAUSE THE VALUES OBTAINED FROM THE RPTING STATIONS AVAILABLE TO US IN THE EARLY MORNING ARE USUALLY INFLUENCED BY THE SAN FRANCISCO/SAN PABLO/RICHARDSON BAY AND ARE NOT ALWAYS REFLECTIONS OF OUR MORE INLAND LAUNCH 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.