INEXPERIENCED PVT PLT DEPARTS HEF IN MARGINAL WX AND FLIES INTO IMC.

Narrative

I WAS AT HEF WITH A RENTED ACFT THAT WAS SCHEDULED TO BE BACK AT ITS BASE ARPT BY XD00. I HAD EXPECTED IMC AT HEF IN THE MORNING; BUT I ALSO EXPECTED -- AND THE FORECASTS HAD SAID -- THAT THE IMC WOULD BURN OFF BY XA00. AS THE DAY CONTINUED; THE IAD TAF WAS CONTINUALLY REVISED; AND EACH TIME IT WAS WORSE THAN THE ONE BEFORE. BY ABOUT XG00; THE TAF FINALLY INDICATED THAT MVFR OR IMC WOULD REMAIN UNTIL WELL AFTER DARK; AT WHICH TIME IT WOULD BEGIN TO RAIN. HOWEVER; STATIONS WELL W AND STATIONS WELL N OF IAD WERE RPTING VFR CONDITIONS. I CALLED FOR A BRIEFING AND HAD A LONG DISCUSSION WITH THE BRIEFER ABOUT THE POSSIBILITY OF LEAVING HEF TO THE W AND CIRCUMVENTING THE AREA OF IMC OVER NORTHERN VIRGINIA AND MARYLAND BY FLYING MORE OR LESS OVER CULPEPPER; MARTINSBURG; AND HARRISBURG. THERE WERE AIRMET'S FOR OCCASIONAL IFR AND MOUNTAIN OBSCURATION; BUT ON THE BASIS OF MY OWN OBSERVATIONS AND WHAT THE BRIEFER TOLD ME; I CONCLUDED THAT I COULD FLY SAFELY AND LEGALLY (IF ONLY THE CEILING AT HEF WOULD RISE TO 1000 FT OR MORE). MY PLAN WAS TO LAND AT AN INTERMEDIATE ARPT IF I FOUND THAT CONDITIONS WERE WORSE THAN I EXPECTED. I GOT IN THE PLANE; STARTED THE ENG; LISTENED TO THE ATIS (RPTING 900 FT CEILING) AND WAITED OPTIMISTICALLY FOR THE TWR TO RPT A 1000 FT CEILING. AFTER WAITING ABOUT 15 MINS; THE TWR ADVISED ME THAT THE CEILING WAS 1000 FT; SO I TOOK OFF. AFTER LEAVING THE HEF CLASS D AIRSPACE; I REMAINED BELOW 700 FT AGL SO THAT I WOULD BE IN CLASS G AIRSPACE. THE CONDITIONS WERE LEGAL; BUT CERTAINLY THE WORST THAT I HAD EVER ENCOUNTERED. I TRIED VARIOUS PATHS THROUGH THE HILLY AREA W OF THE BULL RUN MOUNTAINS BUT COULD NOT FIND A WAY THROUGH. AT ONE POINT; I SAW A HOLE IN THE CLOUD LAYER ABOVE ME; AND BEGAN TO CLB. AS I CLBED; THOUGH; I DECIDED THAT I COULD EASILY GET TRAPPED BTWN CLOUD LAYERS; OR ACCIDENTALLY FLY INTO IMC. HOWEVER; BY THE TIME I DECIDED THAT CLBING HAD BEEN A BAD IDEA; I WAS SURROUNDED BY CLOUDS; INCLUDING A THIN LAYER BENEATH ME; THROUGH WHICH I COULD ONLY BARELY SEE THE GND. I REALIZED THAT I COULD NOT ACCURATELY DETERMINE MY DISTANCE TO THE CLOUDS AROUND ME; OR OVER ME; AND THUS I COULD NOT BE SURE THAT I WAS MAINTAINING LEGAL CLOUD SEPARATION. I KNEW THAT I WAS IN HILLY TERRAIN WITH LOW CEILINGS. IF I LOST SIGHT OF THE GND; I COULD EASILY FLY INTO A HILLSIDE. PANIC SET IN. I MADE THE MOST RADICAL MANEUVER I HAVE EVER MADE (A TIGHT TURN AND DIVE) TO GET BACK THROUGH A HOLE IN THE CLOUD LAYER BENEATH ME BEFORE I LOST SIGHT OF THE GND COMPLETELY. LUCKILY; I MADE IT. IT WAS TOTALLY INSTINCTIVE -- I JUST FOCUSED ON THAT HOLE; AND ON PUTTING THE ACFT THOUGH IT. I DID NOT LOOK AT THE ATTITUDE INDICATOR OR AIRSPACE AT ALL. DID I KEEP THE SPD BELOW VNE? PROBABLY; BUT I COULDN'T SWEAR TO IT. I THEN TOLD POTOMAC ATC THAT I WANTED TO RETURN TO HEF; AND THEY GAVE ME A HDG. WHEN POTOMAC SWITCHED ME TO THE HEF TWR; I SAID I WAS INBOUND FOR LNDG WITH ATIS INFO. THE TWR DIDN'T TELL ME THAT A DIFFERENT ATIS WAS CURRENT; AND I DIDN'T REALIZE THAT I HAD BEEN GONE LONG ENOUGH FOR THE PREVIOUS ATIS TO BECOME INVALID. THE TWR DIDN'T SAY THE CONDITIONS WERE LESS THAN MINIMUM VFR. IN ANY CASE; THE CEILING LOOKED TO ME LIKE IT WAS AT LEAST AS HIGH AS IT HAD BEEN WHEN I HAD DEPARTED; AND THE VISIBILITY WAS AT LEAST 5 MI. I LANDED UNEVENTFULLY. THE MAIN LESSON HERE WAS A NEW RESPECT FOR MVFR; ESPECIALLY WHEN CEILINGS ARE LOW IN HILLY OR MOUNTAINOUS AREAS; OR WHEN DISTANCES TO CLOUDS ARE DIFFICULT TO DETERMINE. THIS INCIDENT ALSO REINFORCED TO ME WHY IT IS SUCH A BAD IDEA GENERALLY TO CLB ABOVE CLOUDS WHILE OPERATING VFR. FAILURE TO OBSERVE THE AIRSPD INDICATOR DURING THE STEEP DSCNT WAS SCARY IN HINDSIGHT. AT THE TIME; THROUGH; I WAS MORE FRIGHTENED OF LOSING SIGHT OF THE GND. (MAYBE THERE SHOULD BE AN AUDIBLE VNE WARNING; SIMILAR TO A STALL HORN?) THE OVERSIGHT IN OBTAINING CURRENT ATIS WAS A LAPSE IN PROCEDURAL DISCIPLINE. I SHOULD HAVE USED AN APCH CHKLIST.