ACR X TCASII TA RA FROM IFR SMA Y MAINTAINING VISUAL SEPARATION.

Narrative

ACR X AT 9000 FT MSL ON THE MILAN 1 ARR TO CVG. I WAS FLYING; AND THE CAPT WAS OPERATING THE RADIO WITH CVG APCH CTL. WE WERE IN VMC ABOVE AN OVCST DECK WITH BASES AT 3300 FT AND TOPS AROUND 4500 FT MSL. INFLT VISIBILITY WAS UNRESTRICTED ABOVE THE STRATUS DECK. AS WE APCHED THE CVG VOR; I MENTIONED TO THE CAPT THAT WE SHOULD BE RECEIVING A TURN AND DSCNT TO ALIGN OURSELVES FOR AN APCH TO RWY 36L; OUR EXPECTED RWY. APCH CTL WAS FAIRLY BUSY WITH OTHER TFC; AND THE CAPT WANTED TO WAIT A BIT LONGER BEFORE CALLING. AT THAT MOMENT; OUR TCASII WENT INTO TA MODE WITH A TARGET AT OUR ALT; APPROX 4 MI AT 12 O'CLOCK. WE JUST STARTED TO SCAN FOR THE TFC WHEN THE APCH CTLR CAME ON IN AN AGITATED VOICE ISSUING AN 'IMMEDIATE' R TURN AND CLB INSTRUCTION. AS I BEGAN THE TURN AND CLB; THE TCASII WENT INTO RA MODE; DIRECTING A CLB AT 1800- 2000 FPM. SINCE I WAS ALREADY IN THE TURNING CLB; I CONTINUED THE TURN AND USED TCASII CLB DIRECTIONS TO MODIFY THE CLB RATE. AFTER I BEGAN THE TURN; THE CAPT RPTED SMA Y IN SIGHT ON HIS SIDE OF THE ACFT. AS WE CONTINUED; THE CAPT INDICATED OUR SEPARATION WOULD BE SAFE. THE TCASII DID NOT ISSUE 'CLR OF CONFLICT' UNTIL AFTER WE WERE PASSING 10000 FT MSL. AS I REDUCED CLB RATE; APCH CTL ISSUED A NEW INSTRUCTION TO DSND TO 7000 FT. THE CAPT SAID THIS LOOKED SAFE; AND TCASII SHOWED NO FURTHER CONFLICT; SO WE FOLLOWED THIS VECTOR. THE REST OF THE APCH AND LNDG WERE UNEVENTFUL. SUPPLEMENTAL INFORMATION FROM ACN 242535: SMA Y WAS 3 MI S OF CVG HDG 360 DEGS AT 9000 FT. POINTED OUT TO ARR/FEEDER SECTOR. ACR X WAS L SEBOUND AT 9000 FT. SMA Y WAS TURNED R TO HDG 090 DEGS. PLT RPTED TFC IN SIGHT. PLT WAS TOLD TO MAINTAIN VISUAL SEPARATION AND CLBED TO 10000 FT. ACR X THEN BEGAN A TCASII PROC TO CLB. I REISSUED VISUAL SEPARATION TO SMA Y AND DSNDED THE ACFT TO 9000 FT. AFTER ENSURED SEPARATION SMA Y WAS CLRED ON COURSE AND DSNDED TO 8000 FT.