Narrative:

The WX forecast called for a clear route, and a broken ceiling at 5000 ft at the destination. I had been flying since mid-morning, and it was now an hour after sunset. It was very dark, since there was no moon and few lights between the cities in the area. I was in level cruise at 3000 ft in VFR WX, following an interstate road that led directly to the destination. On one radio, I was getting VFR radar advisories, while monitoring automated WX stations along the route on the other. One of the stations, perhaps 20 mi ahead, reported broken clouds at 3300 ft. I noticed a cloud directly in our path that looked to be at 2500 ft or 3000 ft, large enough that going around it was not an option. I began a descent to 2000 ft and informed the controller of my intention. After leveling off at 2000 ft, I thought we would be well below the cloud base, and I turned my attention back to identing the cities along the interstate road. My visual contact with the ground was suddenly lost. Realizing I had inadvertently entered the cloud, I told the controller I was in IMC and would be making a 180 degree turn. Before I could execute the maneuver, I was out of the cloud. The controller asked if I was IFR certified and equipped. I answered that I was, and was offered an IFR clearance to the destination. After taking a couple of mins to pull out the charts and approach plates, I accepted, and was issued vectors and a climb to 4000 ft. The flight concluded successfully. After landing, I asked the FBO staff about the WX, and was told that it had come out of nowhere, and was not in the forecast. The dark night had made it difficult to accurately gauge the cloud bases. Even though we were at no time in real danger (plenty of fuel, IFR current pilot, well-equipped aircraft, no icing), it later occurred to me that I should have requested an IFR clearance the moment I saw that there were any clouds at levels lower than forecast. As it was, I believe that informing the controller of my situation and accepting the help he offered was the right decision.

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Original NASA ASRS Text

Title: M20C PLT ENTERS IMC WHILE UNDER JAX VFR ENRTE FLT ADVISORIES AND RESOLVES THE SIT BY REQUESTING A POPUP IFR CLRNC TO DEST.

Narrative: THE WX FORECAST CALLED FOR A CLR RTE, AND A BROKEN CEILING AT 5000 FT AT THE DEST. I HAD BEEN FLYING SINCE MID-MORNING, AND IT WAS NOW AN HR AFTER SUNSET. IT WAS VERY DARK, SINCE THERE WAS NO MOON AND FEW LIGHTS BTWN THE CITIES IN THE AREA. I WAS IN LEVEL CRUISE AT 3000 FT IN VFR WX, FOLLOWING AN INTERSTATE ROAD THAT LED DIRECTLY TO THE DEST. ON ONE RADIO, I WAS GETTING VFR RADAR ADVISORIES, WHILE MONITORING AUTOMATED WX STATIONS ALONG THE RTE ON THE OTHER. ONE OF THE STATIONS, PERHAPS 20 MI AHEAD, RPTED BROKEN CLOUDS AT 3300 FT. I NOTICED A CLOUD DIRECTLY IN OUR PATH THAT LOOKED TO BE AT 2500 FT OR 3000 FT, LARGE ENOUGH THAT GOING AROUND IT WAS NOT AN OPTION. I BEGAN A DSCNT TO 2000 FT AND INFORMED THE CTLR OF MY INTENTION. AFTER LEVELING OFF AT 2000 FT, I THOUGHT WE WOULD BE WELL BELOW THE CLOUD BASE, AND I TURNED MY ATTN BACK TO IDENTING THE CITIES ALONG THE INTERSTATE ROAD. MY VISUAL CONTACT WITH THE GND WAS SUDDENLY LOST. REALIZING I HAD INADVERTENTLY ENTERED THE CLOUD, I TOLD THE CTLR I WAS IN IMC AND WOULD BE MAKING A 180 DEG TURN. BEFORE I COULD EXECUTE THE MANEUVER, I WAS OUT OF THE CLOUD. THE CTLR ASKED IF I WAS IFR CERTIFIED AND EQUIPPED. I ANSWERED THAT I WAS, AND WAS OFFERED AN IFR CLRNC TO THE DEST. AFTER TAKING A COUPLE OF MINS TO PULL OUT THE CHARTS AND APCH PLATES, I ACCEPTED, AND WAS ISSUED VECTORS AND A CLB TO 4000 FT. THE FLT CONCLUDED SUCCESSFULLY. AFTER LNDG, I ASKED THE FBO STAFF ABOUT THE WX, AND WAS TOLD THAT IT HAD COME OUT OF NOWHERE, AND WAS NOT IN THE FORECAST. THE DARK NIGHT HAD MADE IT DIFFICULT TO ACCURATELY GAUGE THE CLOUD BASES. EVEN THOUGH WE WERE AT NO TIME IN REAL DANGER (PLENTY OF FUEL, IFR CURRENT PLT, WELL-EQUIPPED ACFT, NO ICING), IT LATER OCCURRED TO ME THAT I SHOULD HAVE REQUESTED AN IFR CLRNC THE MOMENT I SAW THAT THERE WERE ANY CLOUDS AT LEVELS LOWER THAN FORECAST. AS IT WAS, I BELIEVE THAT INFORMING THE CTLR OF MY SIT AND ACCEPTING THE HELP HE OFFERED WAS THE RIGHT DECISION.

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.