A B757 DSNDING INTO LAX RECEIVES A TCASII RA FROM AN ACFT FOLLOWING. THE B757 EXECUTES A MISSED APCH WHEN HIS TCASII INDICATES AN RA. B757 MAKES AN UNEVENTFUL LNDG AFTER EXECUTING HIS MISSED APCH.

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WE WERE CLRED A VISUAL APCH TO RWY 24L WITH A COMMUTER ACFT ON FINAL FOR THE RWYS 25. APCH ADVISED OF A COMMUTER OFF AT 3 O'CLOCK ON BASE FOR RWY 24R. WE SAW HIM BRIEFLY WHILE HE WAS ON BASE LEG. WITH THIS ACFT BEHIND US NOW; WE GOT A TA FOLLOWED BY A 'CLB; XING; CLB' RA REQUIRING +2000 FPM. OUR PROCS REQUIRE COMPLIANCE WITH ALL RA'S (EXACT VERBIAGE FOLLOWS LATER). WE FOLLOWED THE RA WHICH THEN PUT US OUT OF POS FOR A SAFE; STABILIZED APCH. WE OVERFLEW THE ARPT AND COMPLETED THE SECOND APCH AND LNDG. ACFT MAKING APCHS BASED ON THEIR OWN VISUAL SEPARATION NEED TO UNDERSTAND ANY MANEUVERING DEEMED AGGRESSIVE BY TCASII WILL RESULT IN AN RA AT HIGHER ALTS. MANY COMPANIES HAVE NO CHOICE IN THESE SITS BUT TO COMPLY WITH THE RA. THIS MAY EVEN BE A BOEING LIMITATION IN OUR ACFT OPS MANUAL 'COMPLIANCE WITH TCASII RA'S IS REQUIRED UNLESS THE PIC DETERMINES THAT DOING SO WOULD JEOPARDIZE THE SAFE OP OF THE FLT.' TECHNICALLY; OUR MANUAL ALLOWS SELECTION OF TA-ONLY MODE FOR CLOSELY SPACED APCHS; BUT WITH THE UPDATED TCASII SOFTWARE; I HAVE NEVER NEEDED TO SELECT IT BEFORE (THE OLD SOFTWARE WAS A DIFFERENT STORY). CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR SAW AN LTT TURNING IN FROM HIS R SIDE FOR RWY 24R. HE FEELS CONFIDENT THAT THIS ACFT SET OFF THE TCASII RA. IF HE WERE TO FLY THE APCH AGAIN; THEN HE WOULD SET HIS TCASII TO 'TA' SO HE WOULDN'T HAVE TO FLY A MISSED APCH IN THE EVENT AN ACFT GOT CLOSE TO HIS ACFT. ALTHOUGH HE SAW THE ACFT COME FROM THE R AND THEN TURN IN BEHIND HIS ACFT; HE IS CONFIDENT THAT THIS ACFT PRODUCED THE TCASII RA. BECAUSE HE IS NOT ABSOLUTELY CERTAIN THIS ACFT PRODUCED THE TCASII RA; HE DECIDED TO EXECUTE A MISSED APCH AS INSTRUCTED BY HIS COMPANY POLICY TO ALWAYS REACT TO A TCASII RA.