FLC OF LGT HAVING ACI ENRTE CHK HAD TCASII RA ON APCH TO MKE. DEVIATED FROM ALT TO AVOID TFC.

Narrative

FLT FROM MINNEAPOLIS TO MILWAUKEE. THE FLT WAS SCHEDULED PAX SVC ON WHICH WE WERE RECEIVING A ROUTINE FAA RTE CHK. THE FLT OPERATED UNEVENTFULLY UNTIL ARRIVING IN THE MKE TERMINAL AREA. AFTER RECEIVING THE HDOF FROM CHICAGO CENTER TO MKE APCH CTL AT THE WAITS INTXN; WE WERE ISSUED A 190 DEG HDG AND DSCNT TO 4000 FT FOR A DOWNWIND LEG TO RWY 01L. VISUAL APCHS WERE IN PROGRESS TO MKE AND THE WX WAS CLR WITH 6 MI VISIBILITY IN HAZE. WHILE ESTABLISHED ON THIS HDG AND ALT ABOUT 2 MI SW OF THE ARPT WE HEARD ANOTHER ACFT CHK ON WITH MKE APCH. THE TFC WAS AN SMA APCHING FROM THE W. HE WAS TOLD BY APCH THAT HE WOULD BE #2 FOR THE VISUAL APCH TO 01L FOLLOWING AN LGT. THE SMA SAID THAT HE HAD THE TFC IN SIGHT; AT WHICH POINT APCH OFFERED A VISUAL APCH TO RWY 01R; BASED ON HIS MAINTAINING VISUAL SEPARATION WITH OUR ACFT. THE PLT OF THE SMA ACCEPTED THE APCH WITH ITS CAVEATS AND WAS SO CLRED. SHORTLY THEREAFTER WE WERE CLRED TO DSND FROM 4000 FT TO 2600 FT. I ACKNOWLEDGED THE CLRNC AND THE FO BEGAN A PWR REDUCTION. AT THIS POINT WE WERE ISSUED A BASE LEG TURN TOWARD THE E AND SIMULTANEOUSLY RECEIVED A TFC ADVISORY FROM OUR TCAS EQUIP. THE INTRUDER ACFT WAS APCHING THE 2 MI RING ON THE VSI AT OUT ALT. WE WERE NOT ABLE TO OBTAIN VISUAL ACQUISITION OF THE ACFT DUE TO THE HAZE. THE TA MESSAGE WAS FOLLOWED BY A RESOLUTION ADVISORY AS WE REACHED 3800 FT. THE RESOLUTION ADVISORY DIRECTED US TO 'REDUCE DSCNT' AND WAS FOLLOWED A FEW SECONDS LATER BY A 'CLB; CLB NOW!' ADVISORY. WE RETURNED TO 4000 FT AND MAINTAINED OUR SBOUND HDG. A 'CLR OF CONFLICT' MESSAGE WAS ISSUED SOON AFTER RETURNING TO 4000 FT. DURING THE RESOLUTION THE INTRUDER ACFT WAS SIGHTED BY THE SO AND THE FAA INSPECTOR. EACH SAID THAT THE ACFT WAS WITHIN A MI AT 2 O'CLOCK AND WAS ABOUT 200 FT BELOW US. THE TCASII EQUIP DISPLAYED INFO THAT WAS IN CONCURRENCE WITH THIS. ONCE CLR OF THE CONFLICT WE ADVISED MKE APCH THAT WE RECEIVED AND FOLLOWED A TCAS RESOLUTION ADVISORY. THE CTLR ASKED IF THERE WAS A PROBLEM AND WE TOLD HIM THERE WAS NOT. HE AGAIN ISSUED A BASE LEG TURN AND CLRED US FOR THE VISUAL APCH TO RWY 01L. THE APCH AND LNDG WERE UNEVENTFUL. I FEEL THAT THIS PROBLEM COULD HAVE BEEN AVOIDED. THE PLT OF THE SMA COULD HAVE ALLOWED GREATER SEPARATION WHEN ACCEPTING AN APCH IN WHICH HE WAS TO MAINTAIN SEPARATION FROM ANOTHER ACFT.