PLT OF SMA FLIES APCH TO BNA RWY 02 VICE JWN WHEN GPS SYSTEM IS MIS PROGRAMMED.

Narrative

I WAS ON AN IFR FLT PLAN TO JWN AND THE WX WAS VFR. I WAS FLYING THE VOLLS6 ARR WHICH INCLUDES BNA AS A FIX. BNA APCH BEGAN VECTORING ME FOR A VISUAL TO JWN. SEVERAL MINS LATER; I RPTED JWN IN SIGHT ABOUT 10 MI S OF THE ARPT AND CANCELED MY FLT PLAN. JWN TFC RPTED USING RWY 2 AND I SET UP GPS FOR LNDG ON RWY 2 AT JWN USING THE OBS MODE. AS I APCHED THE RWY ABOUT 5 MI OUT I NOTICED A JET DEPARTING RWY 20 AND I HAD NOT HEARD HIM ON UNICOM FREQ AT JWN. I MADE A SLIGHT (5-10 DEG) TURN R AND AS THE JET PASSED I SAW IT WAS AN AIRLINER. SEVERAL SECONDS LATER; I REALIZED THAT I WAS APCHING BNA RWY 2L; I CHKED FOR ADDITIONAL TFC AND BEGAN A L TURN TO DEPART THE TFC AREA. AT THE SAME TIME I REALIZED THE GPS WAS STILL SET UP ON THE VOLLS6 ARR AND I HAD FOLLOWED IT TO BNA (THIS WAS THE REASON FOR THE PROB; IE; I HAD NOT PROGRAMMED DIRECT TO JWN ONCE I WAS BEING VECTORED OR CLRED FOR THE VISUAL APCH). I CALLED BNA APCH AND ADVISED WHERE I WAS. THEY CONFIRMED AND GAVE ME CLRNC TO JWN. I HAVE MADE THIS TRIP NUMEROUS TIMES AND I WAS WELL RESTED. I SIMPLY DID NOT UPDATE THE FLT FROM VOLLS6 ARR TO DIRECT TO JWN IN THE GPS WHEN I WAS CLRED FOR THE VISUAL TO JWN.