AN MD88 HAS POTENTIAL CONFLICT WITH A KING AIR ON A VECTORED APCH TO ATL; GA.

Narrative

WE WERE IN OUR APCH TO ATL; AN ARPT I'M VERY FAMILIAR WITH. WE HAD JUST BEEN SWITCHED TO THE FINAL APCH CTLR AND UP TO THIS POINT ALL WAS AS EXPECTED. AFTER CHK IN WITH THE CTLR; WE WERE SWITCHED TO A DIFFERENT RWY (RWY 27L) FROM THE PREVIOUS RWY ASSIGNED (RWY 26R). THE CTLR GAVE US THE LOC FREQ. AT THAT POINT I WENT HEADS DOWN TO CHANGE THE RWY ON THE FMS. I SELECTED THE INCORRECT RWY AND AT THAT POINT GAVE UP ON THE FMS. SIMULTANEOUSLY; THE CTLR GAVE US A TURN TO 180 DEGS AND DSCNT TO 2800 FT. WE WERE DSNDING THROUGH 6000 FT. I NOTED NO TFC ON TCASII; BUT HEARD THE CTLR TALKING TO A NON ACR. AS WE WERE APCHING 4000 FT AND A HDG OF 150 DEGS; WE WERE ALERTED BY A TA OF TFC; AND SHORTLY THEREAFTER AN RA ON TCASII AT 11 O'CLOCK POS AND 1 MI. I VISUALLY ACQUIRED A KING AIR IN THAT LOCATION HDG E BELOW US. I KICKED OFF THE AUTOPLT; LEVELED OFF; AND CONTINUED A TURN TO THE SW UNTIL SEPARATION WAS ATTAINED. AT THAT POINT THE CTLR CLRED US TO 240 DEGS AND THE ILS TO RWY 27L. THE ACFT (KING AIR) WAS DSNDING INSIDE OF US ON DOWNWIND UNDER ATL APCH CTL. LESSONS LEARNED: 1) IF ATC IS GOING TO CHANGE RWYS; IT SHOULD BE DONE ON INITIAL CONTACT WITH APCH. 2) MY FAMILIARITY WITH ATL CAUSED ME TO ACCEPT CLRNCS WHICH; IN HINDSIGHT; I WOULD HAVE NOT NORMALLY ACCEPTED. 3) BETTER CREW COORD BTWN MYSELF AND FO. 4) AUTOMATION IS GOOD FOR PREPLANNED EVENTS; NOT RAPIDLY CHANGING SITS. 5) CTLR SHOULD HAVE ALERTED US TO THE LOCATION OF THE KING AIR IF WE WERE PASSING THROUGH HIS ALT. 6) TCASII IS A VALUABLE TOOL.