Narrative:

As we approached cvg from lex VOR (12000 ft at 250 KIAS), approach control turned us to a 020 degree heading for downwind 18L. First officer was flying the aircraft and began to slow down to 210 degrees KIAS to facilitate descent. Approach control cleared us to 7000 ft and while in the descent further cleared us to 4000 ft. Passing 5500 ft, sink rate approximately 2000 FPM, 210 KIAS, flaps 15 degrees, the first officer spotted traffic at 2 O'clock. Traffic was low and appeared to be in a right turn to the west -- away from us. Shortly thereafter, a TA was announced over TCASII. I queried the controller about the traffic and he stated that the traffic was at 4000 ft. It then became evident that the traffic was indeed not turning away from us and posed a serious conflict. The first officer broke the descent and initiated his own climb when an RA sounded over TCASII to climb. We passed over the traffic by approximately 350 ft (4350 ft MSL). This traffic was never called out until I called and the conflict was already established. Once at the gate in cvg, I called approach control on the landline and talked with the supervisor. He told me the traffic was a commuter aircraft small transport descending VFR. I then expressed my concern over being cleared to the same altitude as the obviously known VFR traffic was at. Had the visibility been less and/or TCASII been unavailable, this would've been very close.

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Original NASA ASRS Text

Title: CLOSE PROX ACR-MLG COMMUTER-SMT IN TFC AT CVG.

Narrative: AS WE APCHED CVG FROM LEX VOR (12000 FT AT 250 KIAS), APCH CTL TURNED US TO A 020 DEG HDG FOR DOWNWIND 18L. FO WAS FLYING THE ACFT AND BEGAN TO SLOW DOWN TO 210 DEGS KIAS TO FACILITATE DSCNT. APCH CTL CLRED US TO 7000 FT AND WHILE IN THE DSCNT FURTHER CLRED US TO 4000 FT. PASSING 5500 FT, SINK RATE APPROX 2000 FPM, 210 KIAS, FLAPS 15 DEGS, THE FO SPOTTED TFC AT 2 O'CLOCK. TFC WAS LOW AND APPEARED TO BE IN A R TURN TO THE W -- AWAY FROM US. SHORTLY THEREAFTER, A TA WAS ANNOUNCED OVER TCASII. I QUERIED THE CTLR ABOUT THE TFC AND HE STATED THAT THE TFC WAS AT 4000 FT. IT THEN BECAME EVIDENT THAT THE TFC WAS INDEED NOT TURNING AWAY FROM US AND POSED A SERIOUS CONFLICT. THE FO BROKE THE DSCNT AND INITIATED HIS OWN CLB WHEN AN RA SOUNDED OVER TCASII TO CLB. WE PASSED OVER THE TFC BY APPROX 350 FT (4350 FT MSL). THIS TFC WAS NEVER CALLED OUT UNTIL I CALLED AND THE CONFLICT WAS ALREADY ESTABLISHED. ONCE AT THE GATE IN CVG, I CALLED APCH CTL ON THE LANDLINE AND TALKED WITH THE SUPVR. HE TOLD ME THE TFC WAS A COMMUTER ACFT SMT DSNDING VFR. I THEN EXPRESSED MY CONCERN OVER BEING CLRED TO THE SAME ALT AS THE OBVIOUSLY KNOWN VFR TFC WAS AT. HAD THE VISIBILITY BEEN LESS AND/OR TCASII BEEN UNAVAILABLE, THIS WOULD'VE BEEN VERY CLOSE.

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.