ACR X TCASII RA WITH HELI IN ATA WHILE ON APCH. EVASIVE ACTION TAKEN. SEE AND AVOID CONCEPT.

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ACR X TRACKING THE ILS INBOUND IN VISUAL CONDITIONS AFTER HAVING BEEN CLRED TO LAND. AT APPROX 800 FT AGL; WE RECEIVED A TA FROM OUR TCASII WHICH WE INITIALLY ASSUMED WAS GND TFC ON THE ARPT. THEN AN RA WAS RECEIVED. AS I ARRESTED OUR DSCNT IN RESPONSE WE RECEIVED A 'CLR OF CONFLICT' FROM THE TCASII; FOLLOWED BY ANOTHER RA TO CLB AS I RESUMED DSCNT. BY NOW WE WERE ABOUT 400 FT AGL AND I COULD SEE THE TARGET ON THE TCASII SCREEN SHOWING 200 FT BELOW US AND TO OUR L. AS I RESPONDED TO THE RA ADDING PWR AND ARRESTING OUR DSCNT THE CAPT SPOTTED THE HELI CAUSING THE CONFLICT AND THE TWR ADVISED US OF ITS PRESENCE AS WELL. BY NOW I SAW THE HELI AS WELL; MANEUVERED AROUND IT AND LANDED WITHOUT INCIDENT. THE HELI APPARENTLY HAD BEEN MANEUVERING TO LAND ON A HELIPAD ON THE TXWY IMMEDIATELY TO THE L OF THE APCH LIGHTS TO THE RWY. TWR SHOULD HAVE NOTIFIED US OF THE TFC SOONER. TCASII WORKED AS ADVERTISED; VERY EFFECTIVELY WARNING US OF THE CONFLICT. LESS VIGILANCE BY THE CREW COULD HAVE RESULTED IN DISASTER HAD WE FAILED TO RECOGNIZE THAT THE TCASII WAS NOT MERELY INDICATING GND TFC.