Narrative:

On a solo night flight to sns intended to be accomplished VFR; lower than forecasted ceilings were encountered east of the rom VOR about 30 mins into my flight. Because of terrain considerations I elected to go higher; seeing that there was room to fly VFR and climb between the stratus layers to a higher altitude and continue VFR with ground contact. Upon reaching the higher altitude; climbing from approximately 5000 ft to 6500 ft it became evident that approximately 15 NM ahead I would encounter IMC. I could still see between the layers above me; and I could see stars in between and other aircraft clearly; indicating to me VFR conditions on top; and I knew that I would have to climb to 8000 ft as an MEA if I picked up an IFR clearance. So to be safe; seeing as how it was dark and it was marginal WX conditions; I attained a pop-up IFR clearance from ZOA; knowing that I would climb to 8000 ft and be in the clear. The temperature at 6500 ft at my time of deciding to do this was 4-5 degrees C. Upon reaching 8000 ft I leveled off and it was absolutely dark outside. It became clear to me that I had flown into a layer I had not seen due to the darkness. The temperature at that altitude was -2 degrees C. It was clear that a light amount of rime ice was forming on the leading edge upon visual inspection. Knowing how even a little ice can be dangerous; I tried several different altitudes to see if I could get out of the ice. Stars above me were visible faintly so I thought I was close to the top of the stratus layer; so I first elected to climb to 9000 ft. Upon reaching 9000 ft with stars still visible above me the icing stopped accumulating for a few mins; but at the cold temperature I was certain that the little ice I did accumulate was not going to shed. Based on my knowledge of the local terrain and meteorology I knew that as I approached the higher terrain it was likely that there would be higher ceilings as well that would put me back into the ice; kind of how a stratus layer will climb over a hill and be forced to develop upwards. I was well into a bad situation at that point; and I felt disgusted with myself that I let it get this far out of hand. After being at 9000 ft for a few mins it became clear that I was going to enter icing conditions ahead as my forward and upward visibility was reduced. At this time I requested lower in an attempt to get to a warmer temperature. I was granted 7000 ft which was right at 0 degrees C; and was then granted 6500 ft which put me at +1 degrees C. At this point I was in constant IMC headed nwbound toward sns. I knew that the further west I would go the lower they would allow me to go; so I was assured that the risk of icing was reduced ahead. The rest of the flight proved uneventful with no further accumulation of icing. My mistakes were many in retrospect. Although I had attained an online briefing a few hours earlier when I left sns I did not get adequate updated information for my return flight; and I relied on the forecast I had received a few hours earlier and my experience flying the same route from sns in good VFR conditions. I know not to trust in seeing VFR conditions; especially at night to make a go decision to continue into a situation that can be deteriorating meteorologically. Just because you see clear doesn't mean you'll get there; and it also doesn't mean it'll be that way when you get there. At night; that method of flying can lead to a bad situation. I've learned from this situation to weigh my options more carefully and rely less on what I can see at night in my decision making process. The sole fact that I saw stars and other aircraft doesn't mean that I should continue a flight at night into marginal conditions. There were also many VFR airports back in the central valley with hotels nearby that would have been a better option than inadvertently encountering ice on my flight to sns. From now on I'm going to consider myself IFR only on night crosscountries; and if there is even a possibility of forecasted icing along my route I am not going to be taking an aircraft not approved for known icing.

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Original NASA ASRS Text

Title: C172 ENCOUNTERED ICING ON A NIGHT VFR FLT. PLT WAS ABLE TO OBTAIN IFR CLRNC AND EVENTUALLY EXIT ICING CONDITIONS.

Narrative: ON A SOLO NIGHT FLT TO SNS INTENDED TO BE ACCOMPLISHED VFR; LOWER THAN FORECASTED CEILINGS WERE ENCOUNTERED E OF THE ROM VOR ABOUT 30 MINS INTO MY FLT. BECAUSE OF TERRAIN CONSIDERATIONS I ELECTED TO GO HIGHER; SEEING THAT THERE WAS ROOM TO FLY VFR AND CLB BTWN THE STRATUS LAYERS TO A HIGHER ALT AND CONTINUE VFR WITH GND CONTACT. UPON REACHING THE HIGHER ALT; CLBING FROM APPROX 5000 FT TO 6500 FT IT BECAME EVIDENT THAT APPROX 15 NM AHEAD I WOULD ENCOUNTER IMC. I COULD STILL SEE BTWN THE LAYERS ABOVE ME; AND I COULD SEE STARS IN BTWN AND OTHER ACFT CLEARLY; INDICATING TO ME VFR CONDITIONS ON TOP; AND I KNEW THAT I WOULD HAVE TO CLB TO 8000 FT AS AN MEA IF I PICKED UP AN IFR CLRNC. SO TO BE SAFE; SEEING AS HOW IT WAS DARK AND IT WAS MARGINAL WX CONDITIONS; I ATTAINED A POP-UP IFR CLRNC FROM ZOA; KNOWING THAT I WOULD CLB TO 8000 FT AND BE IN THE CLR. THE TEMP AT 6500 FT AT MY TIME OF DECIDING TO DO THIS WAS 4-5 DEGS C. UPON REACHING 8000 FT I LEVELED OFF AND IT WAS ABSOLUTELY DARK OUTSIDE. IT BECAME CLR TO ME THAT I HAD FLOWN INTO A LAYER I HAD NOT SEEN DUE TO THE DARKNESS. THE TEMP AT THAT ALT WAS -2 DEGS C. IT WAS CLR THAT A LIGHT AMOUNT OF RIME ICE WAS FORMING ON THE LEADING EDGE UPON VISUAL INSPECTION. KNOWING HOW EVEN A LITTLE ICE CAN BE DANGEROUS; I TRIED SEVERAL DIFFERENT ALTS TO SEE IF I COULD GET OUT OF THE ICE. STARS ABOVE ME WERE VISIBLE FAINTLY SO I THOUGHT I WAS CLOSE TO THE TOP OF THE STRATUS LAYER; SO I FIRST ELECTED TO CLB TO 9000 FT. UPON REACHING 9000 FT WITH STARS STILL VISIBLE ABOVE ME THE ICING STOPPED ACCUMULATING FOR A FEW MINS; BUT AT THE COLD TEMP I WAS CERTAIN THAT THE LITTLE ICE I DID ACCUMULATE WAS NOT GOING TO SHED. BASED ON MY KNOWLEDGE OF THE LCL TERRAIN AND METEOROLOGY I KNEW THAT AS I APCHED THE HIGHER TERRAIN IT WAS LIKELY THAT THERE WOULD BE HIGHER CEILINGS AS WELL THAT WOULD PUT ME BACK INTO THE ICE; KIND OF HOW A STRATUS LAYER WILL CLB OVER A HILL AND BE FORCED TO DEVELOP UPWARDS. I WAS WELL INTO A BAD SITUATION AT THAT POINT; AND I FELT DISGUSTED WITH MYSELF THAT I LET IT GET THIS FAR OUT OF HAND. AFTER BEING AT 9000 FT FOR A FEW MINS IT BECAME CLR THAT I WAS GOING TO ENTER ICING CONDITIONS AHEAD AS MY FORWARD AND UPWARD VISIBILITY WAS REDUCED. AT THIS TIME I REQUESTED LOWER IN AN ATTEMPT TO GET TO A WARMER TEMP. I WAS GRANTED 7000 FT WHICH WAS RIGHT AT 0 DEGS C; AND WAS THEN GRANTED 6500 FT WHICH PUT ME AT +1 DEGS C. AT THIS POINT I WAS IN CONSTANT IMC HEADED NWBOUND TOWARD SNS. I KNEW THAT THE FURTHER W I WOULD GO THE LOWER THEY WOULD ALLOW ME TO GO; SO I WAS ASSURED THAT THE RISK OF ICING WAS REDUCED AHEAD. THE REST OF THE FLT PROVED UNEVENTFUL WITH NO FURTHER ACCUMULATION OF ICING. MY MISTAKES WERE MANY IN RETROSPECT. ALTHOUGH I HAD ATTAINED AN ONLINE BRIEFING A FEW HRS EARLIER WHEN I LEFT SNS I DID NOT GET ADEQUATE UPDATED INFO FOR MY RETURN FLT; AND I RELIED ON THE FORECAST I HAD RECEIVED A FEW HRS EARLIER AND MY EXPERIENCE FLYING THE SAME RTE FROM SNS IN GOOD VFR CONDITIONS. I KNOW NOT TO TRUST IN SEEING VFR CONDITIONS; ESPECIALLY AT NIGHT TO MAKE A GO DECISION TO CONTINUE INTO A SITUATION THAT CAN BE DETERIORATING METEOROLOGICALLY. JUST BECAUSE YOU SEE CLR DOESN'T MEAN YOU'LL GET THERE; AND IT ALSO DOESN'T MEAN IT'LL BE THAT WAY WHEN YOU GET THERE. AT NIGHT; THAT METHOD OF FLYING CAN LEAD TO A BAD SITUATION. I'VE LEARNED FROM THIS SITUATION TO WEIGH MY OPTIONS MORE CAREFULLY AND RELY LESS ON WHAT I CAN SEE AT NIGHT IN MY DECISION MAKING PROCESS. THE SOLE FACT THAT I SAW STARS AND OTHER ACFT DOESN'T MEAN THAT I SHOULD CONTINUE A FLT AT NIGHT INTO MARGINAL CONDITIONS. THERE WERE ALSO MANY VFR ARPTS BACK IN THE CENTRAL VALLEY WITH HOTELS NEARBY THAT WOULD HAVE BEEN A BETTER OPTION THAN INADVERTENTLY ENCOUNTERING ICE ON MY FLT TO SNS. FROM NOW ON I'M GOING TO CONSIDER MYSELF IFR ONLY ON NIGHT CROSSCOUNTRIES; AND IF THERE IS EVEN A POSSIBILITY OF FORECASTED ICING ALONG MY RTE I AM NOT GOING TO BE TAKING AN ACFT NOT APPROVED FOR KNOWN ICING.

Data retrieved from NASA's ASRS site as of May 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.