A G200 REPORTS AN RA FROM UNREPORTED TFC ON THE APA SAYGE ARR DESCENDING TO 8000 FT. ATC DID NOT SEE THE TFC.

Narrative

THE FOLLOWING DESCRIBES THE EVENTS LEADING UP TO THE RA. WE WERE ON THE SAYGE 6 ARR TO CENTENNIAL ARPT; WHEN AT SAYGE INTXN (AT FL190/250 KTS; AS CLRED BY ZDV); WE WERE GIVEN A HDG OF 180 DEGS AND TOLD TO DSND TO 11000 FT MSL. AFTER LEVELOFF AT 11000 FT MSL WE WERE GIVEN A HDG OF 230 DEGS AND A DSCNT TO 9000 FT MSL. AFTER A LEVELOFF AT 9000 FT MSL WE WERE ASSIGNED A HDG OF 270 DEGS AND A DSCNT TO 8000 FT MSL. SHORTLY AFTER A ROLLOUT ON THE 270 DEG HDG AND THE DSCNT TO 8000 FT MSL; I RECEIVED A VERBAL 'TFC' FROM THE TCAS AND AN IMMEDIATE 'CLB; CLB.' I IMMEDIATELY AND SIMULTANEOUSLY; DISCONNECTED THE AUTOPLT AND PITCHED THE ACFT UP TO MATCH THE TCAS CLB INDICATIONS. WE NEVER SAW THE OTHER ACFT BUT FOLLOWED IT ON THE TCAS DISPLAY GO UNDERNEATH OUR ACFT. WE RPTED TO DENVER APCH CTL; WHO HAD BEEN VECTORING US FROM SAYGE INTXN; THAT WE HAD RECEIVED AN RA AND WAS NOW RETURNING TO OUR ASSIGNED ALT OF 8000 FT MSL. THE CTLR SAID SHE DID NOT SEE THE CONFLICT TFC. WE CONTINUED TO CENTENNIAL ARPT FOR A VISUAL APCH TO RWY 17L. I HAVE NO IDEA WHY THE CTLR NEVER SAW THE TFC AND WHY WE HAD ONLY A LIMITED TIME TO REACT TO THE TFC. UNTIL THE LAST MOMENT; WE HAD NO INDICATION OF THE TFC THAT EFFECTED THE RA.