3 ACFT -- A BE58; A B737; AND A C210 ALL ATTEMPT TO FLY VISUAL APCHS TO BNA WITH MARGINAL WX. LCL CTLR MUST INTERVENE TO PREVENT NMAC BTWN THE B737 AND THE BE58.

Narrative

I WAS ON MY REGULARLY SCHEDULED RUN FOR XXX; A PART 135 CARGO CARRIER; RETURNING TO BNA AT ABOUT XA10. I WAS BEING VECTORED IN FOR A POSSIBLE VISUAL APCH TO RWY 20L. APCH HAD ME ON A WESTERLY HDG; AND WAS DSNDING ME TO SEE IF I COULD MAKE THE VISUAL. I EXITED THE CLOUDS AT APPROX 2000 FT MSL AND BEGAN TO LOOK FOR THE ARPT. I GOT A VISUAL ON THE ARPT; AND CALLED IT IN SIGHT; AND WAS CLRED FOR THE VISUAL TO RWY 20L. CONSIDERING LANDMARKS OBSERVED UPON EXITING THE CLOUDS; I WAS OVER 8 NM FROM THE ARPT AND VERY NEAR THE FINAL APCH COURSE TO RWY 20L. AS I MANEUVERED FOR THE VISUAL APCH IN A DSNDING TURN; I RECEIVED A HDOF TO NASHVILLE TWR. AT THIS POINT NO OTHER TFC WAS POINTED OUT TO ME; AND NO SPECIFIC HDG OR ALT WAS ASSIGNED. WHEN I SWITCHED OVER TO TWR; I TOLD THEM I WAS ON THE VISUAL TO RWY 20L AND REQUESTED RWY 20C. TWR TOLD ME TO IMMEDIATELY DSND TO 1500 FT AND TURN TO AN EASTERLY HDG. TWR THEN POINTED OUT THE B737 TO ME AND ASKED IF I HAD TFC IN SIGHT. I ADVISED TWR WHEN I GOT THE TFC IN SIGHT (I ONLY SAW LNDG LIGHTS FROM WITHIN THE CLOUDS APPROX 300+ FT ABOVE ME; ABOUT 2000 FT MSL). I WAS THEN CLRED FOR THE VISUAL RWY 20C AND LANDED WITHOUT FURTHER INCIDENT. I BELIEVE THAT THE PROB AROSE DUE TO THE MARGINAL WX AND THE ATTEMPTS AT GETTING VISUAL APCHS IN MARGINAL WX. ANOTHER FACTOR WAS THAT NO TFC WAS EVER POINTED OUT TO ME; NO HDG OR ALT ASSIGNED; AND NO ADVISORY THAT I HAD OVERSHOT THE EXTENDED CTRLINE OF RWY 20L UNTIL IT BECAME A PROB. PERSONALLY; IN HINDSIGHT; IT PROBABLY WOULD HAVE BEEN BETTER TO LINE ALL ACFT ON THE LOC TO BETTER KEEP THEM SEPARATED. ANOTHER SOLUTION WOULD BE TO POINT OUT TFC BEFORE CLRING ME FOR THE VISUAL. SUPPLEMENTAL INFO FROM ACN 622908: I WAS FLYING XXX123 (MY REGULAR PART 135 FLT) INTO BNA. APCHING FROM THE SE; I OBSERVED A DECK OF CLOUDS OVER BNA WITH CEILINGS AROUND 2000 FT AGL AND NO RESTRS TO VISIBILITY. WHILE UNDER THE CTL OF NASHVILLE APCH; I HEARD AIR TAXI X CHK ON AND SAW HIM BEHIND ME. SUBSEQUENTLY; AN ACR Y (A B737); CHKED ON. AS I NEARED BNA; I SPOTTED THE ARPT AND WAS CLRED FOR A VISUAL APCH. AT THIS POINT; I OBSERVED AIR TAXI X APPROX 4 NM TO MY N; 1000 FT ABOVE ME; MAINTAINING HIS LAST ASSIGNED HDG. ATC THEN ASKED THE CREW OF THE B737 IF THEY WOULD LIKE TO TRY A VISUAL APCH. THE B737 ACR Y; PREVIOUSLY BEING VECTORED TO AN ILS; ELECTED TO ATTEMPT A VISUAL APCH. THEY REQUESTED DIFFERENT RWYS NUMEROUS TIMES AND WERE HAVING TROUBLE MAKING VISUAL CONTACT WITH THE ARPT. IT SEEMED THE CTLRS WERE PREOCCUPIED WITH THE B737; AS THEY WERE VECTORED FOR NUMEROUS TURNS AND QUERIED ABOUT WHETHER OR NOT THEY WANTED TO PROCEED WITH A VISUAL APCH OR FLY AN ILS. I WAS HANDED OVER TO THE TWR CTLR AND CLRED TO LAND; HOWEVER; I CONTINUED TO MONITOR THE APCH FREQ ON MY SECONDARY RADIO. I HEAD AIR TAXI X RPT THE ARPT IN SIGHT; AND THE APCH CTLR CLR HIM FOR THE VISUAL APCH. AT THIS TIME; THE CREW OF THE B737 RPTED IMC AND WAS TURNED OFF THEIR COURSE. I LANDED UNEVENTFULLY. TAXIING TO THE RAMP; I OBSERVED THE TWR CTLR ORDER AIR TAXI X TO EXECUTE A RAPID DSCNT TO 1500 FT MSL AND CHANGE HDG. THE CREW OF THE B737 AGAIN CALLED IMC.