B757 EXPERIENCES NMAC WITH C210 ON DSCNT INTO SNA.

Narrative

DURING THE ARR SEGMENT OF FLT INTO SNA; WE WERE GIVEN A DSCNT CLRNC FROM 8000 FT TO 5000 FT BY SOCAL WITH A TA OF A CENTURION INSIDE OF 10 NM. INITIATING A 1500 FPM DSCNT; WE PICKED UP TFC AT A FURTHER DISTANCE AND DETERMINED THAT WAS NOT THE TFC CALLED. WE WERE UNABLE TO PICK UP THE INTENDED TFC AND HEARD NO FURTHER ADVISORY CALLS. AT ABOUT 6200 FT WE RECEIVED A TA IN CLOSE RANGE WHICH IMMEDIATELY WENT INTO AN RA. THE FO IMMEDIATELY INITIATED THE RA RECOVERY AND REVERSED THE DSCNT TO A CLB OF 2000 FPM; WITH THE LOWEST ALT AT THE BOTTOM OF 5700 FT. DURING THE RECOVERY MANEUVER; THE FO SAW THE CENTURION PASS CLOSE ABOARD OFF THE R SIDE; LOW; AND INSIDE OF 500 FT DISTANCE. I NOTIFIED SOCAL OF OUR CLB AND THAT IT WAS DUE TO TFC. SOCAL RESPONDED THAT WE WERE AGAIN CLRED TO 5000 FT AND THAT WE WERE TO CONTACT APCH ON THE NEXT FREQ. I ASKED THE CTLR IF THE TFC WAS AT THEIR CORRECT ASSIGNED ALT AND HE RESPONDED THAT THEY WERE. WE LANDED UNEVENTFULLY AT SNA WHERE I DEBRIEFED THE FLT ATTENDANTS AND CALLED SOCAL TO TALK ABOUT THE SITUATION. SOCAL REALIZED THEIR ERROR AND TOLD ME THEY THOUGHT OUR DSCNT RATE WOULD HAVE PUT US BELOW THE TFC. IN RETROSPECT; THEY STATED THAT THEY SHOULD HAVE LEVELED US OFF. I TOLD THEM THAT I ALWAYS APPRECIATE A VECTOR AWAY BECAUSE IT ENSURES SEPARATION IN BOTH DIMENSIONS AND IT HELPS IN PICKING UP THE TFC WHICH MAY BE BELOW THE NOSE OF OUR ACFT. AT TIMES I BELIEVE THAT CTLRS ARE TOO COMFORTABLE WITH ALT ONLY DE-CONFLICTION. IN ANY SITUATION THAT MAY BE SOMEWHAT CLOSE; ESPECIALLY WITH SMALL CIVILIAN VFR ACFT THAT MAY NOT BE FLYING OR ADHERING TO PROPER ALTS; WE SHOULD RECEIVE A VECTOR TO ENSURE ADEQUATE SEPARATION. THIS COULD HAVE ALL BEEN AVOIDED WITH A 20 DEG CHK TURN.