SMA PLT BECOMES LOST; MAKES PRECAUTIONARY LNDG.

Narrative

WHILE ON A VFR FLT FROM ABILENE; TX; TO KERRVILLE; TX; I BECAME LOST AND DISORIENTED. PRIOR TO THE FLT; A WX BRIEFING WAS OBTAINED AND A FLT PLAN WAS FILED. LORAN WAS THE PRIMARY MEANS OF NAV. THE ACFT IS A VINTAGE SMA AND HAD NO OTHER MEANS OF ELECTRONIC NAV ON BOARD. THE ACFT IS AIRWORTHY AND A CURRENT SAN ANTONIO SECTIONAL WAS ON BOARD. DURING THE FLT S; I ENCOUNTERED INCREASING CLOUDINESS AND LIGHT PRECIPITATION. VISIBILITY WAS GREATLY REDUCED BUT REMAINED COMFORTABLY VFR. ENRTE TO KERRVILLE; THE LORAN WAS APPARENTLY INDICATING A HDG TO FLY THAT WAS IN ERROR BY ABOUT 10 DEGS. THE LORAN DID NOT INDICATE A LOSS OF SIGNAL OR A DEGRADATION OF SIGNAL STRENGTH. AS I APCHED THE KERRVILLE AREA; I WAS NOT SURE OF MY POS. THE POS INDICATED BY THE LORAN DID NOT MATCH ANY MAP REF I COULD LOCATE. I CALLED FLT WATCH TO REQUEST HELP IN DETERMINING MY POS. THEY HANDED ME OFF TO ZHU. I REQUESTED A VECTOR TO THE NEAREST ARPT. ZHU REQUESTED THAT I SQUAWK 7700 XPONDER CODE AND IDENT. I COMPLIED; BUT APPARENTLY; THE RADAR COVERAGE IN THIS PARTICULAR AREA IS NOT GOOD AT THE ALT THAT I WAS AT (4000 FT MSL; 2400 FT AGL). I WAS UNABLE TO CLB HIGHER AND REMAIN VFR. ZHU; SAT APCH; AND SAN ANGELO FSS ATTEMPTED A RADIO DF FIX; BUT WERE UNABLE TO VERIFY MY POS. NEITHER HOUSTON NOR SAN ANTONIO COULD ESTABLISH MY LOCATION. SAN ANGELO FSS ALSO TRIED BUT COULD NOT GET A GOOD FIX. I DESCRIBED THE LANDMARKS AROUND ME TO ZHU. I ADVISED ZHU THAT I WAS LOW ON FUEL AND WAS ORBITING A PVT RANCH STRIP. ZHU SAID THEY 'THOUGHT THEY NEW MY POS' AND OFFERED A VECTOR TO LEAKEY; TX. SINCE BOTH HOUSTON AND I WERE UNSURE OF MY POS; AND EXACT FUEL REMAINING; I ELECTED TO MAKE A PRECAUTIONARY LNDG ON THE RANCH STRIP. THE LNDG WAS UNEVENTFUL. I WAS ABLE TO PURCHASE FUEL AND DETERMINE MY EXACT LOCATION. AFTER LNDG; THE RANCH FOREMAN SHOWED ME MY LOCATION ON THE SAN ANTONIO SECTIONAL. THE RANCH STRIP THAT I LANDED ON IS AN IMPROVED STRIP BUT IS NOT DEPICTED ON THE SAN ANTONIO SECTIONAL AND WOULD; THEREFORE; MAKE DETERMINING MY POS BY DESCRIPTION TO CTR ALMOST IMPOSSIBLE. THEY WOULD HAVE NO CHART REF THAT WOULD MATCH WHAT I DESCRIBED TO THEM. I RESUMED THE TRIP AND PROCEEDED UNEVENTFULLY TO KERRVILLE. AT KERRVILLE; I CALLED SAN ANGELO FSS AND ADVISED THEM THAT I HAD ARRIVED AND THE ONLY DAMAGE WAS TO MY EGO. I BELIEVE THE FAILURE OF THE LORAN WAS ATTRIBUTABLE TO SIGNAL DEGRADATION CAUSED BY RAIN IN THE VICINITY. THE FAILURE OF THE PLT WAS MY FAILURE TO ADEQUATELY XCHK THE LORAN WITH KNOWN MAP REF ENRTE. ALTHOUGH I AM GRATEFUL FOR THE OFFERED HELP; I AM CONCERNED THAT ZHU WAS WILLING TO GIVE ME A VECTOR TO LEAKEY WITHOUT BEING SURE OF MY POS IN SPITE OF A KNOWN LOW FUEL SIT. IN SURVEYING THE COUNTRY THAT I WOULD HAVE HAD TO CROSS; THERE WAS NO PLACE TO LAND IF I HAD EXHAUSTED THE REMAINING FUEL. THAT WAS THE DETERMINING FACTOR IN REFUSING THE VECTOR AND EXECUTING THE PRECAUTIONARY LNDG. IN THIS CASE; BLIND FAITH IN THE ACCURACY OF THE LORAN WAS MISPLACED. AS PIC; I SHOULD HAVE MONITORED MY POS ON THE SECTIONAL AS THE FLT PROGRESSED. LESSON LEARNED.