LGT VECTORED FOR APCH HAD TCASII RA. STOPS DSCNT; ACQUIRES AND MAINTAINS VISUAL ON TFC.

Narrative

WE WERE BEING VECTORED BY LAS APCH CTL FOR AN ILS RWY 25. HDG WAS ASSIGNED 340 AND DSCNT TO 8000. NEXT INSTRUCTION WAS TURN TO 310 AND DSND TO 6000. WHILE IN THIS DSNDING TURN BTWN 6500 AND 6000 WE GOT A FIRST TCASII INDICATION WHICH WAS A RED SQUARE AND AN IMMEDIATE RA OF 'REDUCE DSCNT.' THE PF (CAPT) ACCOMPLISHED THIS AS WE MADE VISUAL CONTACT AT 10 O'CLOCK; SLIGHTLY LOW WITH WHAT APPEARED TO BE AN SMA. THE PNF (FO) ALSO HAD A VISUAL CONTACT AND IMMEDIATELY ASKED APCH CTL ABOUT THE TFC SINCE WE HAD NOT RECEIVED ANY TA. THE CTLR SEEMED UNAWARE; AT THIS POINT; AS TO THE TFC POS OR IT'S ALT OR VERT DIRECTION. THE PF THEN TOOK AN EVASIVE ACTION OF MAINTAINING CONSTANT VISUAL CONTACT WITH THE L WING LOW UNTIL THE TFC PASSED SAFELY BELOW AND BEHIND. RETURNING TO THE INSTS SHOWED 5800 WITH AN IMMEDIATE RETURN TO 6000. WHILE THIS WAS HAPPENING; THE PNF MADE AN ADDITIONAL COMMENT TO APCH CTL ABOUT THE RA AND OUR PROX TO THE ACFT. BY NOW THE CTLR GAINED KNOWLEDGE OF THE TFC AND TOLD US THAT THE TARGET WAS ON ANOTHER SECTOR'S CTL AT 6500 VFR AND ASKED FOR OUR ALT. WE HAD RESUMED 6000 AFTER THE EVASIVE MANEUVER AND REPLIED '6000.' HE REPLIED THAT HE HAD JUST SEEN 5700 AND THAT WAS THE REASON FOR THE RA. WE HAD IN FACT RECEIVED THE RA AT 6000 OR ABOVE; PRIOR TO THE EVASIVE ACTION. THIS ENTIRE EVENT CAUSED US TO BE VERY HIGH AND CLOSE FOR THE VISUAL LNDG WHICH WAS SAFELY ACCOMPLISHED WITHOUT INCIDENT.