Narrative:

I called 1-800-WX-brief and received a standard briefing at about XA30. The briefer stated that the WX would be MVFR through my intended course; with a bit of IFR near ZZZ2 and then MVFR after that. The WX at ZZZ1 appeared better than the information that the briefer had; and ZZZ2 is located on top of a mountain 3700+ ft MSL; so I figured that IMC at ZZZ2 meant that the cloud bases were about the same as they were at ZZZ1. This was a mistake. I departed from ZZZ1 and climbed through the broken cloud layer. The cloud bases were around 4000 ft and the tops were around 6500 ft. I climbed to 6500 ft and then up to 7500 ft. The broken cloud layer soon turned to an undercast; but since the WX was supposed to get worse and then get better; I continued to fly my course. After I passed ZZZ2; the undercast started to rise. I climbed to 9500 ft MSL as the undercast was rising; and soon I was in the clouds. I should have turned back; but I started flying the aircraft as per the private pilot instrument training and the IFR flying I've done as a pilot rated passenger. Since I expected the WX to get better; I pressed on thinking that the undercast would descend back to the broken undercast. I flew this way for 10 or 15 mins. This was another mistake. Soon; it became clear that this was here to stay. I had been monitoring the CTAF frequencys for nearby airports; and there was quite a bit of traffic at ZZZ3. So; I descended from 9500 ft down to about 4800 ft; which was at the ht of the highest obstacle on the section of the chart that I was using. No ground contact; so I started climbing and executed a 180 degree turn. A few holes allowed me to see some wooded mountaintops below me; but the holes were too small and the terrain too rugged to risk a descent into the VFR conditions below. The mountaintops were closer than I would have preferred -- maybe 1000 ft below. I started climbing back up with 8500 ft MSL as my goal. Descending that low was yet another mistake. As I flew back and climbed; the WX gradually got better until I was VFR on top. Looking ahead; it appeared that the WX didn't get much better toward ZZZ1; so I elected to fly to ZZZ3 instead and; if worse came to worst; have them talk me through one of the instrument approachs. On the way to ZZZ3; I found a hole in the clouds; and made a spiraling VFR descent through the hole. When I popped out of the bottom (about 3000 ft MSL); I proceeded to ZZZ3. I called ZZZ3 and they allowed me to land VFR. They directed me to runway 6; but after I mentioned that I'd been in an inadvertent IMC; they had me fly straight-in to runway 24. I thanked them for the priority. I sat at the FBO at ZZZ3 for about 3 hours. I called a friend to have her come and pick me up; but canceled after the WX started improving. About XF15; the WX had improved and the ZZZ1 AWOS was reporting visibility of 7 mi and with a broken cloud layer of 4000 ft AGL. I departed for ZZZ1 after bumbling my way through ZZZ3's ATC. Part of it was due to my not having the airport information for ZZZ3; and part of it was that I had an out-of-date chart. My GPS was up-to-date (legal for VFR); but it's easier to get radio frequencys by looking at the sectional -- and I got the out-of-date ATIS frequency. The flight to ZZZ1 was uneventful -- at least compared to the departing flight. I flew lower than I would have normally; and below the mountaintops. The controller wanted me to fly northwest to make his job easier; but I was low enough that flying northwest would have put me into conflict with the mountain. I flew along the mountain as best I could; and followed the railroad tracks home. I did a nice short-field landing at ZZZ1; too. Lessons learned/corrective actions taken: 1) the WX is unpredictable and I've really learned my limits on this one. Corrective action: don't do this again! 2) the WX situation changed slowly enough that I could get used to each change; one at a time. Before today; when I thought about VFR into IMC; I always thought about flying into a vertical wall of cloud; and I figured I was smart enough that such a thing wouldn't happen to me. But; that wasn't how it happened -- the transition happened over a span of several mins and happened gradually enough that there wasn't any surprises big enough to startle me into turning back; and so I delayed my 180 degree turn much longer than I should have. 3) GPS -- I had a garmin 295 handheld GPS. It was a lifesaver; provided great situational awareness; and a great check for the gyro instruments in the aircraft. However; I would have turned back much earlier if I hadn't had it. 4) I didn't call center because I didn't have their frequency handy. I should have. In the future; I will look this up before I depart. 5) I've been a little overconfident lately -- I'm close to taking my IFR written and I've flown aircraft in IMC; but not as PIC. I've also successfully pushed the WX envelope in VFR conditions lately; and it was easier than expected. Today; I pushed too far. 6) throw away out-of-date charts. Just because the database in the GPS is up-to-date doesn't mean that the old chart will be correct. The main difference that I noticed was the ATIS frequency at ZZZ3. The out-of-date chart that I had with me is now in a trash can at ZZZ1. 7) an instrument rating is necessary for the environment in which I fly. I've contacted my favorite CFI to see if he's ready to start instructing me on the art of instrument flying; and I will be very eager to attend the instrument ground school that I had scheduled to attend. 8) I wouldn't have attempted this flight if I'd had a passenger. That should have given me pause. Maybe I should consider myself as a passenger in addition to considering myself to be PIC? 9) the mode C in the aircraft I was flying has been an intermittent problem for other members of the club. It was off by 600 ft when I approached ZZZ3 (when I advised them of a potential problem) and wasn't reporting during my departure. Just because the flight I planned didn't require a mode C doesn't mean that the actual conditions didn't require it. All in all; I'm happy to be back on the ground today. I'm going to go to a picnic this evening and enjoy the company of my friends and neighbors. I've read this chain of events in many accident reports; and always thought that I was too smart for it to happen to me -- but I wasn't prepared for the gradual nature of the developing emergency. When I descended to the level of the highest obstacle on the chart (below the MEA for the area); I was probably one mistake away from being a statistic. This is quite sobering; and I plan to be more cautious and better prepared (instrument rated) in the future.

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Original NASA ASRS Text

Title: A VFR C150 PLT ENCOUNTERS IMC AND COMPLETES AN UNSCHEDULED LNDG.

Narrative: I CALLED 1-800-WX-BRIEF AND RECEIVED A STANDARD BRIEFING AT ABOUT XA30. THE BRIEFER STATED THAT THE WX WOULD BE MVFR THROUGH MY INTENDED COURSE; WITH A BIT OF IFR NEAR ZZZ2 AND THEN MVFR AFTER THAT. THE WX AT ZZZ1 APPEARED BETTER THAN THE INFO THAT THE BRIEFER HAD; AND ZZZ2 IS LOCATED ON TOP OF A MOUNTAIN 3700+ FT MSL; SO I FIGURED THAT IMC AT ZZZ2 MEANT THAT THE CLOUD BASES WERE ABOUT THE SAME AS THEY WERE AT ZZZ1. THIS WAS A MISTAKE. I DEPARTED FROM ZZZ1 AND CLBED THROUGH THE BROKEN CLOUD LAYER. THE CLOUD BASES WERE AROUND 4000 FT AND THE TOPS WERE AROUND 6500 FT. I CLBED TO 6500 FT AND THEN UP TO 7500 FT. THE BROKEN CLOUD LAYER SOON TURNED TO AN UNDERCAST; BUT SINCE THE WX WAS SUPPOSED TO GET WORSE AND THEN GET BETTER; I CONTINUED TO FLY MY COURSE. AFTER I PASSED ZZZ2; THE UNDERCAST STARTED TO RISE. I CLBED TO 9500 FT MSL AS THE UNDERCAST WAS RISING; AND SOON I WAS IN THE CLOUDS. I SHOULD HAVE TURNED BACK; BUT I STARTED FLYING THE ACFT AS PER THE PVT PLT INST TRAINING AND THE IFR FLYING I'VE DONE AS A PLT RATED PAX. SINCE I EXPECTED THE WX TO GET BETTER; I PRESSED ON THINKING THAT THE UNDERCAST WOULD DSND BACK TO THE BROKEN UNDERCAST. I FLEW THIS WAY FOR 10 OR 15 MINS. THIS WAS ANOTHER MISTAKE. SOON; IT BECAME CLR THAT THIS WAS HERE TO STAY. I HAD BEEN MONITORING THE CTAF FREQS FOR NEARBY ARPTS; AND THERE WAS QUITE A BIT OF TFC AT ZZZ3. SO; I DSNDED FROM 9500 FT DOWN TO ABOUT 4800 FT; WHICH WAS AT THE HT OF THE HIGHEST OBSTACLE ON THE SECTION OF THE CHART THAT I WAS USING. NO GND CONTACT; SO I STARTED CLBING AND EXECUTED A 180 DEG TURN. A FEW HOLES ALLOWED ME TO SEE SOME WOODED MOUNTAINTOPS BELOW ME; BUT THE HOLES WERE TOO SMALL AND THE TERRAIN TOO RUGGED TO RISK A DSCNT INTO THE VFR CONDITIONS BELOW. THE MOUNTAINTOPS WERE CLOSER THAN I WOULD HAVE PREFERRED -- MAYBE 1000 FT BELOW. I STARTED CLBING BACK UP WITH 8500 FT MSL AS MY GOAL. DSNDING THAT LOW WAS YET ANOTHER MISTAKE. AS I FLEW BACK AND CLBED; THE WX GRADUALLY GOT BETTER UNTIL I WAS VFR ON TOP. LOOKING AHEAD; IT APPEARED THAT THE WX DIDN'T GET MUCH BETTER TOWARD ZZZ1; SO I ELECTED TO FLY TO ZZZ3 INSTEAD AND; IF WORSE CAME TO WORST; HAVE THEM TALK ME THROUGH ONE OF THE INST APCHS. ON THE WAY TO ZZZ3; I FOUND A HOLE IN THE CLOUDS; AND MADE A SPIRALING VFR DSCNT THROUGH THE HOLE. WHEN I POPPED OUT OF THE BOTTOM (ABOUT 3000 FT MSL); I PROCEEDED TO ZZZ3. I CALLED ZZZ3 AND THEY ALLOWED ME TO LAND VFR. THEY DIRECTED ME TO RWY 6; BUT AFTER I MENTIONED THAT I'D BEEN IN AN INADVERTENT IMC; THEY HAD ME FLY STRAIGHT-IN TO RWY 24. I THANKED THEM FOR THE PRIORITY. I SAT AT THE FBO AT ZZZ3 FOR ABOUT 3 HRS. I CALLED A FRIEND TO HAVE HER COME AND PICK ME UP; BUT CANCELED AFTER THE WX STARTED IMPROVING. ABOUT XF15; THE WX HAD IMPROVED AND THE ZZZ1 AWOS WAS RPTING VISIBILITY OF 7 MI AND WITH A BROKEN CLOUD LAYER OF 4000 FT AGL. I DEPARTED FOR ZZZ1 AFTER BUMBLING MY WAY THROUGH ZZZ3'S ATC. PART OF IT WAS DUE TO MY NOT HAVING THE ARPT INFO FOR ZZZ3; AND PART OF IT WAS THAT I HAD AN OUT-OF-DATE CHART. MY GPS WAS UP-TO-DATE (LEGAL FOR VFR); BUT IT'S EASIER TO GET RADIO FREQS BY LOOKING AT THE SECTIONAL -- AND I GOT THE OUT-OF-DATE ATIS FREQ. THE FLT TO ZZZ1 WAS UNEVENTFUL -- AT LEAST COMPARED TO THE DEPARTING FLT. I FLEW LOWER THAN I WOULD HAVE NORMALLY; AND BELOW THE MOUNTAINTOPS. THE CTLR WANTED ME TO FLY NW TO MAKE HIS JOB EASIER; BUT I WAS LOW ENOUGH THAT FLYING NW WOULD HAVE PUT ME INTO CONFLICT WITH THE MOUNTAIN. I FLEW ALONG THE MOUNTAIN AS BEST I COULD; AND FOLLOWED THE RAILROAD TRACKS HOME. I DID A NICE SHORT-FIELD LNDG AT ZZZ1; TOO. LESSONS LEARNED/CORRECTIVE ACTIONS TAKEN: 1) THE WX IS UNPREDICTABLE AND I'VE REALLY LEARNED MY LIMITS ON THIS ONE. CORRECTIVE ACTION: DON'T DO THIS AGAIN! 2) THE WX SIT CHANGED SLOWLY ENOUGH THAT I COULD GET USED TO EACH CHANGE; ONE AT A TIME. BEFORE TODAY; WHEN I THOUGHT ABOUT VFR INTO IMC; I ALWAYS THOUGHT ABOUT FLYING INTO A VERTICAL WALL OF CLOUD; AND I FIGURED I WAS SMART ENOUGH THAT SUCH A THING WOULDN'T HAPPEN TO ME. BUT; THAT WASN'T HOW IT HAPPENED -- THE TRANSITION HAPPENED OVER A SPAN OF SEVERAL MINS AND HAPPENED GRADUALLY ENOUGH THAT THERE WASN'T ANY SURPRISES BIG ENOUGH TO STARTLE ME INTO TURNING BACK; AND SO I DELAYED MY 180 DEG TURN MUCH LONGER THAN I SHOULD HAVE. 3) GPS -- I HAD A GARMIN 295 HANDHELD GPS. IT WAS A LIFESAVER; PROVIDED GREAT SITUATIONAL AWARENESS; AND A GREAT CHK FOR THE GYRO INSTS IN THE ACFT. HOWEVER; I WOULD HAVE TURNED BACK MUCH EARLIER IF I HADN'T HAD IT. 4) I DIDN'T CALL CTR BECAUSE I DIDN'T HAVE THEIR FREQ HANDY. I SHOULD HAVE. IN THE FUTURE; I WILL LOOK THIS UP BEFORE I DEPART. 5) I'VE BEEN A LITTLE OVERCONFIDENT LATELY -- I'M CLOSE TO TAKING MY IFR WRITTEN AND I'VE FLOWN ACFT IN IMC; BUT NOT AS PIC. I'VE ALSO SUCCESSFULLY PUSHED THE WX ENVELOPE IN VFR CONDITIONS LATELY; AND IT WAS EASIER THAN EXPECTED. TODAY; I PUSHED TOO FAR. 6) THROW AWAY OUT-OF-DATE CHARTS. JUST BECAUSE THE DATABASE IN THE GPS IS UP-TO-DATE DOESN'T MEAN THAT THE OLD CHART WILL BE CORRECT. THE MAIN DIFFERENCE THAT I NOTICED WAS THE ATIS FREQ AT ZZZ3. THE OUT-OF-DATE CHART THAT I HAD WITH ME IS NOW IN A TRASH CAN AT ZZZ1. 7) AN INST RATING IS NECESSARY FOR THE ENVIRONMENT IN WHICH I FLY. I'VE CONTACTED MY FAVORITE CFI TO SEE IF HE'S READY TO START INSTRUCTING ME ON THE ART OF INST FLYING; AND I WILL BE VERY EAGER TO ATTEND THE INST GND SCHOOL THAT I HAD SCHEDULED TO ATTEND. 8) I WOULDN'T HAVE ATTEMPTED THIS FLT IF I'D HAD A PAX. THAT SHOULD HAVE GIVEN ME PAUSE. MAYBE I SHOULD CONSIDER MYSELF AS A PAX IN ADDITION TO CONSIDERING MYSELF TO BE PIC? 9) THE MODE C IN THE ACFT I WAS FLYING HAS BEEN AN INTERMITTENT PROB FOR OTHER MEMBERS OF THE CLUB. IT WAS OFF BY 600 FT WHEN I APCHED ZZZ3 (WHEN I ADVISED THEM OF A POTENTIAL PROB) AND WASN'T RPTING DURING MY DEP. JUST BECAUSE THE FLT I PLANNED DIDN'T REQUIRE A MODE C DOESN'T MEAN THAT THE ACTUAL CONDITIONS DIDN'T REQUIRE IT. ALL IN ALL; I'M HAPPY TO BE BACK ON THE GND TODAY. I'M GOING TO GO TO A PICNIC THIS EVENING AND ENJOY THE COMPANY OF MY FRIENDS AND NEIGHBORS. I'VE READ THIS CHAIN OF EVENTS IN MANY ACCIDENT RPTS; AND ALWAYS THOUGHT THAT I WAS TOO SMART FOR IT TO HAPPEN TO ME -- BUT I WASN'T PREPARED FOR THE GRADUAL NATURE OF THE DEVELOPING EMER. WHEN I DSNDED TO THE LEVEL OF THE HIGHEST OBSTACLE ON THE CHART (BELOW THE MEA FOR THE AREA); I WAS PROBABLY ONE MISTAKE AWAY FROM BEING A STATISTIC. THIS IS QUITE SOBERING; AND I PLAN TO BE MORE CAUTIOUS AND BETTER PREPARED (INST RATED) IN THE FUTURE.

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.