Narrative:

I was proceeding from visibility to oak VFR, with VFR services being supplied by stockton approach. I was heading towards mountainous terrain and the cloud cover was lowered over that area. I could see still 35-40 NM to the pass that I usually go through when I am flying this route. Stockton approach had me squawk xxxx. I continued on descending and I was easily maintaining cloud clearance and terrain clearance. The area that this was occurring is very sparsely populated. As I approached my pass conditions were changing dramatically to the worse. There was a small front that was approaching the area and a lot of other people were getting caught out. The oak ATIS had earlier reported 20 mi visibility, few clouds at 2500 ft and overcast at 6500 ft. I was monitoring bay approach, when there was a flood of requests for IFR clrncs and approachs going into oak and hwd. My pass was closing in fast, so I reversed course. Upon reversal I noted that conditions behind me had decayed. I was only marginally able to maintain VFR, and knew that my chances of getting a clearance expeditiously was not very likely unless I declared an emergency. I flew out of the area maintaining this marginal VFR by basically keeping the terrain in sight and glimpsing at the moving map display on the GPS. I did my best to avoid any controled airspace though I may have inadvertently strayed into some. I was pretty scared and tried to maintain a safe altitude above terrain. After flying wbound I was able to get into a clear area, and circumnav the WX till I got to tracy airport, where I contacted stockton approach and got an IFR clearance to oak. I would say that in the future I will request an IFR clearance when the potential of these kinds of conditions exist prior to getting into congested airspace. I probably should have attempted to contact bay approach anyway to see if they could assist me. If things would have gotten much worse I would have had to face my embarrassment for not having flown IFR, and declared an emergency. At no time was I really close to terrain, radar altimeter was set to 1000 ft and it never alerted. The situation is something I am embarrassed about, I should have never let myself get there. I guess we all have a lapse of reason at times.

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Original NASA ASRS Text

Title: C208B ACFT ON VFR FLT PLAN ENCOUNTERED DETERIORATING WX AND RPTR PLT HAD TO DIVERT WHILE HAVING DIFFICULTY MAINTAINING VFR CONDITIONS. AN IFR CLRNC WAS OBTAINED THROUGH A TRACON FACILITY AND RPTR CONTINUED IFR.

Narrative: I WAS PROCEEDING FROM VIS TO OAK VFR, WITH VFR SVCS BEING SUPPLIED BY STOCKTON APCH. I WAS HEADING TOWARDS MOUNTAINOUS TERRAIN AND THE CLOUD COVER WAS LOWERED OVER THAT AREA. I COULD SEE STILL 35-40 NM TO THE PASS THAT I USUALLY GO THROUGH WHEN I AM FLYING THIS RTE. STOCKTON APCH HAD ME SQUAWK xxxx. I CONTINUED ON DSNDING AND I WAS EASILY MAINTAINING CLOUD CLRNC AND TERRAIN CLRNC. THE AREA THAT THIS WAS OCCURRING IS VERY SPARSELY POPULATED. AS I APCHED MY PASS CONDITIONS WERE CHANGING DRAMATICALLY TO THE WORSE. THERE WAS A SMALL FRONT THAT WAS APCHING THE AREA AND A LOT OF OTHER PEOPLE WERE GETTING CAUGHT OUT. THE OAK ATIS HAD EARLIER RPTED 20 MI VISIBILITY, FEW CLOUDS AT 2500 FT AND OVCST AT 6500 FT. I WAS MONITORING BAY APCH, WHEN THERE WAS A FLOOD OF REQUESTS FOR IFR CLRNCS AND APCHS GOING INTO OAK AND HWD. MY PASS WAS CLOSING IN FAST, SO I REVERSED COURSE. UPON REVERSAL I NOTED THAT CONDITIONS BEHIND ME HAD DECAYED. I WAS ONLY MARGINALLY ABLE TO MAINTAIN VFR, AND KNEW THAT MY CHANCES OF GETTING A CLRNC EXPEDITIOUSLY WAS NOT VERY LIKELY UNLESS I DECLARED AN EMER. I FLEW OUT OF THE AREA MAINTAINING THIS MARGINAL VFR BY BASICALLY KEEPING THE TERRAIN IN SIGHT AND GLIMPSING AT THE MOVING MAP DISPLAY ON THE GPS. I DID MY BEST TO AVOID ANY CTLED AIRSPACE THOUGH I MAY HAVE INADVERTENTLY STRAYED INTO SOME. I WAS PRETTY SCARED AND TRIED TO MAINTAIN A SAFE ALT ABOVE TERRAIN. AFTER FLYING WBOUND I WAS ABLE TO GET INTO A CLR AREA, AND CIRCUMNAV THE WX TILL I GOT TO TRACY ARPT, WHERE I CONTACTED STOCKTON APCH AND GOT AN IFR CLRNC TO OAK. I WOULD SAY THAT IN THE FUTURE I WILL REQUEST AN IFR CLRNC WHEN THE POTENTIAL OF THESE KINDS OF CONDITIONS EXIST PRIOR TO GETTING INTO CONGESTED AIRSPACE. I PROBABLY SHOULD HAVE ATTEMPTED TO CONTACT BAY APCH ANYWAY TO SEE IF THEY COULD ASSIST ME. IF THINGS WOULD HAVE GOTTEN MUCH WORSE I WOULD HAVE HAD TO FACE MY EMBARRASSMENT FOR NOT HAVING FLOWN IFR, AND DECLARED AN EMER. AT NO TIME WAS I REALLY CLOSE TO TERRAIN, RADAR ALTIMETER WAS SET TO 1000 FT AND IT NEVER ALERTED. THE SIT IS SOMETHING I AM EMBARRASSED ABOUT, I SHOULD HAVE NEVER LET MYSELF GET THERE. I GUESS WE ALL HAVE A LAPSE OF REASON AT TIMES.

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.