B757 CREW INBOUND TO LAS INSTRUCTED TO FLY THE LUXOR ARR; BUT NOT ASSIGNED A RWY UNTIL 15 MI FROM THE ARPT.

Narrative

WE WERE FLT PLANNED FROM SLC TO LAS ON THE LUXOR ARR. ON CONTACT WITH ZLA; WE WERE DIRECTED TO FLY DIRECT KASINO AND THE KASINO ARR. NO RWY WAS GIVEN. THE ATIS STATED THAT LAS WAS LNDG RWY 25 AND RWY 19. SINCE RWY 25 IS THE RWY USUALLY USED; WE PROGRAMMED THE FMS FOR THE KASINO ARR RWY 25L; WHICH IS OUR USUAL LNDG RWY. HOWEVER; LAS VEGAS APCH WANTED US TO LAND ON RWY 19. THE ARR IS PREDICATED ON THE LNDG RWY. BECAUSE WE WERE NOT ISSUED A RWY FOR ARR AND ASSUMED RWY 25; WE MISSED A TURN ON THE ARR MIRAJ FIX FOR RWY 19. NO CONFLICT WAS CREATED THAT WE KNOW OF. BECAUSE EACH ARR HAS DIFFERENT ARR PATHS AND ALTS BASED ON RWY AT LAS; IT IS ESSENTIAL THAT ZLA AND LAS APCH STATE THE RWY WHEN CLRING AN ACFT ON THE ARR. THE LACK OF THIS INFO CAUSES THE FLC TO ASSUME A RWY BASED ON PAST EXPERIENCE. THIS SIT CAUSED A LEVEL OF CONFUSION IN THE COCKPIT DURING THE LAST 15 NM OF THE ARR. THE PLTS AND CTLRS HAVE TO HAVE THE SAME INFO. UNLESS THE CTLR TELLS THE PLTS WHAT THEY ARE EXPECTING THE PLTS WILL OPERATE ON PAST EXPERIENCE.