C172 PLT; UPON ENCOUNTERING ICING CONDITIONS ENRTE TO DEST; FLIES IFR FLT PLAN AND LANDS SHORT OF INTENDED DEST AT SYI; TN.

Narrative

THE FLT ORIGINATED AT LGC; GA; IFR TO BNA; TN. IN LGC I GOT A STANDARD BRIEFING FOR THE RTE; INCLUDING AN AIRMET FOR ICING FROM THE FREEZING LEVEL TO 12000 FT; FREEZING LEVEL FORECAST FROM 8000 FT SLOPING TO 4000 FT. PIREPS INDICATED TRACE TO NO ICING BELOW 4000 FT AND NONE RPTED S OF BNA. FLT PROCEEDED NORMALLY UNTIL 15-20 NM W OF RMG; GA; WHERE I BECAME CONCERNED ABOUT THE APCHING NIGHT AND TEMP DROP. CALLING ATLANTA FLT WATCH I RECEIVED THE SAME ICING FORECAST AND FREEZING LEVEL FORECAST AND PIREPS. I DECIDED NOT TO CONTINUE THE FLT AT THIS TIME AND RPTED DIRECT RMG. ATLANTA GAVE ME 2000 FT AND I EXITED THE OVCST ON THE WAY DOWN AT 3500 FT. AT THIS TIME; I DECIDED TO TRY TO CONTINUE VFR; WX PERMITTING; AND CONTINUED ON TOWARDS BNA. WHEN 80 NM OFF THE RTE 60 OF BNA; THE WX DETERIORATED TO WHERE I COULD NO LONGER MAINTAIN VFR AT A SAFE ALT. THE OUTSIDE AIR TEMP WAS 5 DEGS C AT THIS TIME AT 3000 FT. I FILED AN IFR FLT PLAN; PICKED UP A CLRNC AND CONTINUED. APPROX 60 NM FROM BNA THE OUTSIDE AIR TEMP STARTED TO DROP CLOSE TO 0 DEGS C AT 4000 FT (MY IFR ASSIGNED ALT) AND I REQUESTED LOWER. AT THIS TIME; MY PAX STARTED TO FEEL MOTION SICK AND ONE BEGAN TO VOMIT. MEMPHIS TOLD ME I COULD GET LOWER IN 6 MINS. APPROX 50 NM FROM BNA; MEMPHIS GAVE ME 3000 FT. AT THIS TIME I HAD DETECTED A TRACE OF ICE ON THE WINDSHIELD. AT 3000 FT THE ICING STOPPED; HOWEVER; THE TEMP WAS DROPPING TOWARDS FREEZING AGAIN. AFTER MONITORING VARIOUS AWOS STATIONS FARTHER ALONG THE RTE RPTING TEMPS AT OR BELOW FREEZING; I DECIDED TO DISCONTINUE THE FLT AND LAND AT SYI; 40 MI SE OF BNA. THE VOR 36 APCH INTO SYI WAS COMPLETED WITHOUT COMPLICATIONS.