Narrative:

I flew from ZZZ1 to ZZZ2 with a fuel stop at ZZZ3. The WX reports showed beautiful WX in ZZZ1 and in ZZZ2 and the WX charts showed perfectly clear skies the entire way. When I got to ZZZ3 it was covered with a low layer of freezing fog. I had more than an hour and a half worth of fuel remaining; so I continued on to my alternate 50 mi away. When I got there it was also fogged in. The next closest airport was ZZZ; 70 mi away. The AWOS at ZZZ was reporting 200 ft ceilings and 2 mi visibility. I didn't have enough fuel left to make it; so I had to land. I'm currently working on my instrument rating; so I had the training to make it through the fog; but I've never flown in IMC and I was terrified to do so. However; there was nothing else I could do. The landing was smooth and uneventful thanks in great part to a moving map GPS system I have installed in my plane. When I realized that I had to land in IMC conditions; knowing that pilots with more training and experience than me; have been killed in similar sits; I was really kicking myself for getting into that situation. But I couldn't immediately think of anything I had done wrong. Since then I've had a lot of time to think about it and I've decided there were several factors that got me into that situation. By far the biggest thing factoring into it was simply lack of experience. When I got to bam and saw the fog; the idea that the fog might stretch on for hundreds of miles; never entered my mind. If I had thought there was even a chance the fog might cover the entire state; I could easily have turned around and fueled up in other airports. However; lack of experience wasn't the only problem. Another factor was my GPS system; which makes navigation a no brainer. If I didn't have the GPS system; I would have (and should have even with it) prepared and filed a very detailed flight plan and when FSS gave me the WX briefing I would have discovered the fog. So I learned that fog is something you have to take very seriously. It's not shown on a lot of WX charts; so it's easy to miss if you don't spend enough time flight planning. Also it's easy to get lax with today's advanced avionics. You might think that you have all the information you need; and there's no need to do a traditional detailed flight plan; and 99% of the time you'll get away with it. It's that 1% of the time that will get you. As GPS systems become more common in small aircraft; I think more and more pilots will make the same mistake I made.

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Original NASA ASRS Text

Title: NON-INSTRUMENT RATED Q200 PLT ENCOUNTERS UNEXPECTED FOG AND DESCENDS IN IMC TO A NON-TWRED ALTERNATE ARPT DUE TO FUEL CONSIDERATIONS.

Narrative: I FLEW FROM ZZZ1 TO ZZZ2 WITH A FUEL STOP AT ZZZ3. THE WX RPTS SHOWED BEAUTIFUL WX IN ZZZ1 AND IN ZZZ2 AND THE WX CHARTS SHOWED PERFECTLY CLR SKIES THE ENTIRE WAY. WHEN I GOT TO ZZZ3 IT WAS COVERED WITH A LOW LAYER OF FREEZING FOG. I HAD MORE THAN AN HOUR AND A HALF WORTH OF FUEL REMAINING; SO I CONTINUED ON TO MY ALTERNATE 50 MI AWAY. WHEN I GOT THERE IT WAS ALSO FOGGED IN. THE NEXT CLOSEST ARPT WAS ZZZ; 70 MI AWAY. THE AWOS AT ZZZ WAS RPTING 200 FT CEILINGS AND 2 MI VISIBILITY. I DIDN'T HAVE ENOUGH FUEL LEFT TO MAKE IT; SO I HAD TO LAND. I'M CURRENTLY WORKING ON MY INSTRUMENT RATING; SO I HAD THE TRAINING TO MAKE IT THROUGH THE FOG; BUT I'VE NEVER FLOWN IN IMC AND I WAS TERRIFIED TO DO SO. HOWEVER; THERE WAS NOTHING ELSE I COULD DO. THE LNDG WAS SMOOTH AND UNEVENTFUL THANKS IN GREAT PART TO A MOVING MAP GPS SYSTEM I HAVE INSTALLED IN MY PLANE. WHEN I REALIZED THAT I HAD TO LAND IN IMC CONDITIONS; KNOWING THAT PLTS WITH MORE TRAINING AND EXPERIENCE THAN ME; HAVE BEEN KILLED IN SIMILAR SITS; I WAS REALLY KICKING MYSELF FOR GETTING INTO THAT SIT. BUT I COULDN'T IMMEDIATELY THINK OF ANYTHING I HAD DONE WRONG. SINCE THEN I'VE HAD A LOT OF TIME TO THINK ABOUT IT AND I'VE DECIDED THERE WERE SEVERAL FACTORS THAT GOT ME INTO THAT SIT. BY FAR THE BIGGEST THING FACTORING INTO IT WAS SIMPLY LACK OF EXPERIENCE. WHEN I GOT TO BAM AND SAW THE FOG; THE IDEA THAT THE FOG MIGHT STRETCH ON FOR HUNDREDS OF MILES; NEVER ENTERED MY MIND. IF I HAD THOUGHT THERE WAS EVEN A CHANCE THE FOG MIGHT COVER THE ENTIRE STATE; I COULD EASILY HAVE TURNED AROUND AND FUELED UP IN OTHER ARPTS. HOWEVER; LACK OF EXPERIENCE WASN'T THE ONLY PROB. ANOTHER FACTOR WAS MY GPS SYSTEM; WHICH MAKES NAV A NO BRAINER. IF I DIDN'T HAVE THE GPS SYSTEM; I WOULD HAVE (AND SHOULD HAVE EVEN WITH IT) PREPARED AND FILED A VERY DETAILED FLT PLAN AND WHEN FSS GAVE ME THE WX BRIEFING I WOULD HAVE DISCOVERED THE FOG. SO I LEARNED THAT FOG IS SOMETHING YOU HAVE TO TAKE VERY SERIOUSLY. IT'S NOT SHOWN ON A LOT OF WX CHARTS; SO IT'S EASY TO MISS IF YOU DON'T SPEND ENOUGH TIME FLT PLANNING. ALSO IT'S EASY TO GET LAX WITH TODAY'S ADVANCED AVIONICS. YOU MIGHT THINK THAT YOU HAVE ALL THE INFO YOU NEED; AND THERE'S NO NEED TO DO A TRADITIONAL DETAILED FLT PLAN; AND 99% OF THE TIME YOU'LL GET AWAY WITH IT. IT'S THAT 1% OF THE TIME THAT WILL GET YOU. AS GPS SYSTEMS BECOME MORE COMMON IN SMALL ACFT; I THINK MORE AND MORE PLTS WILL MAKE THE SAME MISTAKE I MADE.

Data retrieved from NASA's ASRS site as of January 2009 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.