Narrative:

VFR flight from mht to W66, with fuel stop in fdk. Obtained 2 WX briefings before the XA45 departure. Forecast was clear along route, 40 mi visibility, with 4-5 KTS scattered in md/va area. Valid until XO00 hours. At harrisburg, PA, called flight watch for forecast and current conditions in the md/va area. Reported 4100 scattered 4500 scattered 10 mi visibility, both bwi and iad. Approaching carroll county airport, md, encountered 2000 ft overcast to scattered with light rain. Landed at carroll county for fuel and updated WX briefing due to lower ceilings than expected. Briefer reported current at bwi and iad as 4100 scattered 4300 scattered 10 mi visibility. Reported leesburg as 4100 scattered. No report for fdk or W66. I also called a pilot friend with an ibm-pc and WX charts, he also reported good. Briefer did report mountain obscuration, and that light rain would be encountered upon arrival at W66. He said he was almost calling marginal VFR due to WX due to arrive in W66 area, but said depending on how comfortable you feel as a pilot would determine if I should go. He said he would call it VFR at this time. Departing carroll county at XB00 MSL, heading 252 degrees, tracking fdk VOR inbound, the VOR needle indicated right of course. I tried 230 degree, 210 degree, and 200 degree headings with no change in needle. I then encountered moderate rain and had to descend to 1200 ft MSL to stay clear of clouds. Visibility dropped to approximately 1-3 mi out the side windows. Thinking my VOR was in error, I turned back to a 252 degree heading, looking for landmarks on the TCA chart. Unsure of actual position at 1200 ft MSL, now encountering moderate to heavy rain and marginal conditions, I decided to tune dulles approach on 126.1. With no reply after 2 attempts, I felt it necessary to tune 121.5 and ask for help before it was too late. I called, 'dulles approach west inbound fdk, heading 252 degrees, 1200 ft MSL. Could you verify my position. I am encountering moderate to heavy rain with reduced visibility.' he had me tune 7700 in the transponder and asked for my last known position after carroll county. I did not know. He then asked if any prominent ground points were visible, I said no. I then crossed a highway and could see what looked like the outskirts of frederick city. Just then, my VOR needle swung full right, I looked right off my wing tip, and there was fdk airport 2 mi away. I thanked dulles and landed uneventfully. I should never have taken off from carroll county, as I should have realized that WX conditions were much worse than reported. Contributing factors I feel significant was the lack of available WX data for fdk area. My radio was unable to tune fdk AWOS, although it was not reporting the conditions I encountered (verbal from local pilot). I also should have not expected my VOR to work well at low altitude (1200 ft MSL). This whole episode could have been avoided had I just parked my aircraft at carroll county and called a cabin attendant!

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Original NASA ASRS Text

Title: SMA BECOMES DISORIENTED AS VOR INDICATIONS AND WX DETERIORATE.

Narrative: VFR FLT FROM MHT TO W66, WITH FUEL STOP IN FDK. OBTAINED 2 WX BRIEFINGS BEFORE THE XA45 DEP. FORECAST WAS CLR ALONG RTE, 40 MI VISIBILITY, WITH 4-5 KTS SCATTERED IN MD/VA AREA. VALID UNTIL XO00 HRS. AT HARRISBURG, PA, CALLED FLT WATCH FOR FORECAST AND CURRENT CONDITIONS IN THE MD/VA AREA. RPTED 4100 SCATTERED 4500 SCATTERED 10 MI VISIBILITY, BOTH BWI AND IAD. APCHING CARROLL COUNTY ARPT, MD, ENCOUNTERED 2000 FT OVCST TO SCATTERED WITH LIGHT RAIN. LANDED AT CARROLL COUNTY FOR FUEL AND UPDATED WX BRIEFING DUE TO LOWER CEILINGS THAN EXPECTED. BRIEFER RPTED CURRENT AT BWI AND IAD AS 4100 SCATTERED 4300 SCATTERED 10 MI VISIBILITY. RPTED LEESBURG AS 4100 SCATTERED. NO RPT FOR FDK OR W66. I ALSO CALLED A PLT FRIEND WITH AN IBM-PC AND WX CHARTS, HE ALSO RPTED GOOD. BRIEFER DID RPT MOUNTAIN OBSCURATION, AND THAT LIGHT RAIN WOULD BE ENCOUNTERED UPON ARR AT W66. HE SAID HE WAS ALMOST CALLING MARGINAL VFR DUE TO WX DUE TO ARRIVE IN W66 AREA, BUT SAID DEPENDING ON HOW COMFORTABLE YOU FEEL AS A PLT WOULD DETERMINE IF I SHOULD GO. HE SAID HE WOULD CALL IT VFR AT THIS TIME. DEPARTING CARROLL COUNTY AT XB00 MSL, HDG 252 DEGS, TRACKING FDK VOR INBOUND, THE VOR NEEDLE INDICATED R OF COURSE. I TRIED 230 DEG, 210 DEG, AND 200 DEG HDGS WITH NO CHANGE IN NEEDLE. I THEN ENCOUNTERED MODERATE RAIN AND HAD TO DSND TO 1200 FT MSL TO STAY CLR OF CLOUDS. VISIBILITY DROPPED TO APPROX 1-3 MI OUT THE SIDE WINDOWS. THINKING MY VOR WAS IN ERROR, I TURNED BACK TO A 252 DEG HDG, LOOKING FOR LANDMARKS ON THE TCA CHART. UNSURE OF ACTUAL POS AT 1200 FT MSL, NOW ENCOUNTERING MODERATE TO HVY RAIN AND MARGINAL CONDITIONS, I DECIDED TO TUNE DULLES APCH ON 126.1. WITH NO REPLY AFTER 2 ATTEMPTS, I FELT IT NECESSARY TO TUNE 121.5 AND ASK FOR HELP BEFORE IT WAS TOO LATE. I CALLED, 'DULLES APCH W INBOUND FDK, HDG 252 DEGS, 1200 FT MSL. COULD YOU VERIFY MY POS. I AM ENCOUNTERING MODERATE TO HVY RAIN WITH REDUCED VISIBILITY.' HE HAD ME TUNE 7700 IN THE XPONDER AND ASKED FOR MY LAST KNOWN POS AFTER CARROLL COUNTY. I DID NOT KNOW. HE THEN ASKED IF ANY PROMINENT GND POINTS WERE VISIBLE, I SAID NO. I THEN CROSSED A HWY AND COULD SEE WHAT LOOKED LIKE THE OUTSKIRTS OF FREDERICK CITY. JUST THEN, MY VOR NEEDLE SWUNG FULL R, I LOOKED R OFF MY WING TIP, AND THERE WAS FDK ARPT 2 MI AWAY. I THANKED DULLES AND LANDED UNEVENTFULLY. I SHOULD NEVER HAVE TAKEN OFF FROM CARROLL COUNTY, AS I SHOULD HAVE REALIZED THAT WX CONDITIONS WERE MUCH WORSE THAN RPTED. CONTRIBUTING FACTORS I FEEL SIGNIFICANT WAS THE LACK OF AVAILABLE WX DATA FOR FDK AREA. MY RADIO WAS UNABLE TO TUNE FDK AWOS, ALTHOUGH IT WAS NOT RPTING THE CONDITIONS I ENCOUNTERED (VERBAL FROM LCL PLT). I ALSO SHOULD HAVE NOT EXPECTED MY VOR TO WORK WELL AT LOW ALT (1200 FT MSL). THIS WHOLE EPISODE COULD HAVE BEEN AVOIDED HAD I JUST PARKED MY ACFT AT CARROLL COUNTY AND CALLED A CAB!

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.