FLC OF AN LGT INTERRUPTED THEIR FINAL APCH INSIDE THE OM AND CLBED IN RESPONSE TO A TCASII RA CAUSED BY A HELI PREVIOUSLY CLRED ACROSS THEIR FLT PATH.

Narrative

ACR X (RADIO CALL) WAS CLRED FOR VISUAL APCH TO RWY 25L AT LAS. LOC AND GS WAS INTERCEPTED AT APPROX 20 MI. LNDG GEAR WAS EXTENDED AND LNDG CHKLIST COMPLETED PRIOR TO FAF (RELIN). FLT WAS CLRED TO LAND AFTER PASSING RELIN. TCASII TA 'TFC' ALERT SOUNDED PASSING APPROX 1400 FT AGL; FOLLOWED IMMEDIATELY BY TCASII RA 'CLB; CLB.' A CLB WAS INITIATED AND TCASII RA CHANGED TO 'MONITOR VERT SPD' INDICATING LEVEL FLT OR CLB WAS ACCEPTABLE. FOLLOWING A 'CLR OF TFC' ALERT; A NORMAL STABILIZED APCH AND LNDG WAS MADE TO RWY 25L. AFTER THE TCASII ALERT AND EVASIVE MANEUVER WERE COMPLETED; THE TWR WAS TOLD OF THE RA AND ASKED ABOUT TFC IN THE AREA. WE WERE TOLD THEY HAD BOTH OF US IN SIGHT AND THE SECOND ACFT WAS A HELI. ONCE PARKED AT THE GATE; THE TWR WAS CALLED ON THE PHONE. THE SUPVR INDICATED THAT APCH CTL SHOULD HAVE NOTIFIED US OF THE TFC. POSSIBLE CONTRIBUTING FACTORS: 1) RADIO TFC APPEARED HVY ON APCH CTL. 2) OUR FLT WAS NOT TURNED OVER TO THE TWR UNTIL INSIDE THE OM. 3) NO MENTION OF TFC WAS MADE BY APCH OR TWR; ALTHOUGH TWR HAD TIME TO CLR US TO LAND AND CLR A FLT FOR TKOF ON RWY 25R BEFORE OUR TCASII RA EVENT.