Narrative:

After landing at sdf with an ever decreasing RVR, I attempted to taxi to the FBO. At the beginning of the approach, the RVR for runway 19 was 2500 ft. The tower reported 1400 ft when I was inside the marker. However, I found it to be a good 1/2 mi upon reaching 300 ft. On the rollout, however, RVR decreased rapidly, making taxiing difficult. I was instructed to taxi via taxiway G to the ramp, crossing runway 29 en route. Approaching to cross runway 29, you literally could not see the taxiway on the other side. Tower informed I could taxi straight across to the ramp. After crossing runway 29, I continued to taxi on what I thought was 'G.' just past the fire house, taxiway G branches off to the right. I saw the fire house go by but I did not see the taxiway branch to the right. I continued following the centerline which was now taxiway H. I knew I was lost when I got to runway 19. I stopped just short of 19 and quickly did a 180. The tower had issued a takeoff clearance to another aircraft at the same time I noticed I was in the wrong place. Tower canceled the other aircraft's takeoff clearance. I was turning around. Further taxi was without incident. The incident was caused by a very low visibility, coupled with the fork in the road and the pilot's unfamiliarity with the airport. I believe this particular incident could have been avoided by the pilot asking for help sooner and closer adherence to the airport diagram. The controller did an excellent job issuing instructions and a conflict really never arose. The tower probably could not even see I had taken a wrong turn.

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Original NASA ASRS Text

Title: AN ATX SMA GOT LOST WHILE TAXIING IN THE FOG AT SDF.

Narrative: AFTER LNDG AT SDF WITH AN EVER DECREASING RVR, I ATTEMPTED TO TAXI TO THE FBO. AT THE BEGINNING OF THE APCH, THE RVR FOR RWY 19 WAS 2500 FT. THE TWR RPTED 1400 FT WHEN I WAS INSIDE THE MARKER. HOWEVER, I FOUND IT TO BE A GOOD 1/2 MI UPON REACHING 300 FT. ON THE ROLLOUT, HOWEVER, RVR DECREASED RAPIDLY, MAKING TAXIING DIFFICULT. I WAS INSTRUCTED TO TAXI VIA TXWY G TO THE RAMP, XING RWY 29 ENRTE. APCHING TO CROSS RWY 29, YOU LITERALLY COULD NOT SEE THE TXWY ON THE OTHER SIDE. TWR INFORMED I COULD TAXI STRAIGHT ACROSS TO THE RAMP. AFTER XING RWY 29, I CONTINUED TO TAXI ON WHAT I THOUGHT WAS 'G.' JUST PAST THE FIRE HOUSE, TXWY G BRANCHES OFF TO THE R. I SAW THE FIRE HOUSE GO BY BUT I DID NOT SEE THE TXWY BRANCH TO THE R. I CONTINUED FOLLOWING THE CTRLINE WHICH WAS NOW TXWY H. I KNEW I WAS LOST WHEN I GOT TO RWY 19. I STOPPED JUST SHORT OF 19 AND QUICKLY DID A 180. THE TWR HAD ISSUED A TKOF CLRNC TO ANOTHER ACFT AT THE SAME TIME I NOTICED I WAS IN THE WRONG PLACE. TWR CANCELED THE OTHER ACFT'S TKOF CLRNC. I WAS TURNING AROUND. FURTHER TAXI WAS WITHOUT INCIDENT. THE INCIDENT WAS CAUSED BY A VERY LOW VISIBILITY, COUPLED WITH THE FORK IN THE ROAD AND THE PLT'S UNFAMILIARITY WITH THE ARPT. I BELIEVE THIS PARTICULAR INCIDENT COULD HAVE BEEN AVOIDED BY THE PLT ASKING FOR HELP SOONER AND CLOSER ADHERENCE TO THE ARPT DIAGRAM. THE CTLR DID AN EXCELLENT JOB ISSUING INSTRUCTIONS AND A CONFLICT REALLY NEVER AROSE. THE TWR PROBABLY COULD NOT EVEN SEE I HAD TAKEN A WRONG TURN.

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.