Narrative:

I was flying the aircraft on final approach to 25L. At approximately 8 NM out, we received a TCASII TA. The scope indicated that the traffic was close aboard and slightly below to our right. The first officer looked out and back to his right and spotted an light transport air carrier approximately 100-150 ft to our right, slightly behind, and about 200 ft below us. Shortly after the TA, the TCASII issued a RA instructing us to decrease our rate of descent, which I did. We were able to maintain separation from the light transport and silence the RA without having to go around. Our first officer asked the tower controller if he could see us and the other aircraft visually. He acknowledged in the affirmative and told us that the light transport was for 25R. The tone of his voice indicated that he was not concerned about the close proximity of the light transport to us. We had been cleared for the approach to 25L, and we were centered on the 25L localizer throughout the entire approach. After the TCASII alerts had ceased, we were able to continue the approach to a normal landing. After arriving at the gate, our first officer called the operations department for the other carrier, and obtained the flight number of the other aircraft. He was able to contact the crew and talk to them about the event. The captain of the light transport told him that their clearance was to intercept the 25L localizer and proceed inbound until they had us in sight. Then, at that time, they were cleared for a visual approach to 25R. (I do remember hearing the tower ask them several times if they had us in sight). They apparently slowed down to maintain what appeared to them to be adequate separation behind us. They admitted that they were somewhat slow to transition to the right to line up on 25R. Their action did not provide enough separation to satisfy our TCASII system, and it issued the proper TA and RA. Our suggestion would be that during parallel VFR approachs, an aircraft cleared to sidestep for an approach to an adjacent runway should not delay doing so in order to prevent an unnecessary TCASII alert and potential midair conflict, even when visual contact with another aircraft has been established. Supplemental information from acn 200067. I believe the light transport was very slow to correct to 25R after intercepting (cleared to) 25L localizer. He may have seen us the entire time but no regard/concern for both aircraft's passengers thoughts and possible ignorance to the TCASII system and cockpit disruption we received! He saw us, we did not see him until after the disruption in our cockpit. I strongly feel it should be mandatory for both aircraft to be told of each other's position (VFR and IFR) and the controling agency to receive acknowledgement from both. Also to avoid TCASII interruption/disruption, a little more concern for spacing should be accomplished by ATC and aircraft crews to prevent uneasiness amongst crews and passengers. We were never told by ATC of the existence and the light transport crew was very slow to correct for close proximity of the 2 aircraft.

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Original NASA ASRS Text

Title: TCASII RA DISTURBS ACR LGT CREW ON STRAIGHT IN APCH TO LAX. RA FROM ACR LTT IN CLOSE PROX IN TRAIL TO R.

Narrative: I WAS FLYING THE ACFT ON FINAL APCH TO 25L. AT APPROX 8 NM OUT, WE RECEIVED A TCASII TA. THE SCOPE INDICATED THAT THE TFC WAS CLOSE ABOARD AND SLIGHTLY BELOW TO OUR R. THE FO LOOKED OUT AND BACK TO HIS R AND SPOTTED AN LTT ACR APPROX 100-150 FT TO OUR R, SLIGHTLY BEHIND, AND ABOUT 200 FT BELOW US. SHORTLY AFTER THE TA, THE TCASII ISSUED A RA INSTRUCTING US TO DECREASE OUR RATE OF DSCNT, WHICH I DID. WE WERE ABLE TO MAINTAIN SEPARATION FROM THE LTT AND SILENCE THE RA WITHOUT HAVING TO GAR. OUR FO ASKED THE TWR CTLR IF HE COULD SEE US AND THE OTHER ACFT VISUALLY. HE ACKNOWLEDGED IN THE AFFIRMATIVE AND TOLD US THAT THE LTT WAS FOR 25R. THE TONE OF HIS VOICE INDICATED THAT HE WAS NOT CONCERNED ABOUT THE CLOSE PROX OF THE LTT TO US. WE HAD BEEN CLRED FOR THE APCH TO 25L, AND WE WERE CENTERED ON THE 25L LOC THROUGHOUT THE ENTIRE APCH. AFTER THE TCASII ALERTS HAD CEASED, WE WERE ABLE TO CONTINUE THE APCH TO A NORMAL LNDG. AFTER ARRIVING AT THE GATE, OUR FO CALLED THE OPS DEPT FOR THE OTHER CARRIER, AND OBTAINED THE FLT NUMBER OF THE OTHER ACFT. HE WAS ABLE TO CONTACT THE CREW AND TALK TO THEM ABOUT THE EVENT. THE CAPT OF THE LTT TOLD HIM THAT THEIR CLRNC WAS TO INTERCEPT THE 25L LOC AND PROCEED INBOUND UNTIL THEY HAD US IN SIGHT. THEN, AT THAT TIME, THEY WERE CLRED FOR A VISUAL APCH TO 25R. (I DO REMEMBER HEARING THE TWR ASK THEM SEVERAL TIMES IF THEY HAD US IN SIGHT). THEY APPARENTLY SLOWED DOWN TO MAINTAIN WHAT APPEARED TO THEM TO BE ADEQUATE SEPARATION BEHIND US. THEY ADMITTED THAT THEY WERE SOMEWHAT SLOW TO TRANSITION TO THE R TO LINE UP ON 25R. THEIR ACTION DID NOT PROVIDE ENOUGH SEPARATION TO SATISFY OUR TCASII SYS, AND IT ISSUED THE PROPER TA AND RA. OUR SUGGESTION WOULD BE THAT DURING PARALLEL VFR APCHS, AN ACFT CLRED TO SIDESTEP FOR AN APCH TO AN ADJACENT RWY SHOULD NOT DELAY DOING SO IN ORDER TO PREVENT AN UNNECESSARY TCASII ALERT AND POTENTIAL MIDAIR CONFLICT, EVEN WHEN VISUAL CONTACT WITH ANOTHER ACFT HAS BEEN ESTABLISHED. SUPPLEMENTAL INFO FROM ACN 200067. I BELIEVE THE LTT WAS VERY SLOW TO CORRECT TO 25R AFTER INTERCEPTING (CLRED TO) 25L LOC. HE MAY HAVE SEEN US THE ENTIRE TIME BUT NO REGARD/CONCERN FOR BOTH ACFT'S PAXS THOUGHTS AND POSSIBLE IGNORANCE TO THE TCASII SYS AND COCKPIT DISRUPTION WE RECEIVED! HE SAW US, WE DID NOT SEE HIM UNTIL AFTER THE DISRUPTION IN OUR COCKPIT. I STRONGLY FEEL IT SHOULD BE MANDATORY FOR BOTH ACFT TO BE TOLD OF EACH OTHER'S POS (VFR AND IFR) AND THE CTLING AGENCY TO RECEIVE ACKNOWLEDGEMENT FROM BOTH. ALSO TO AVOID TCASII INTERRUPTION/DISRUPTION, A LITTLE MORE CONCERN FOR SPACING SHOULD BE ACCOMPLISHED BY ATC AND ACFT CREWS TO PREVENT UNEASINESS AMONGST CREWS AND PAXS. WE WERE NEVER TOLD BY ATC OF THE EXISTENCE AND THE LTT CREW WAS VERY SLOW TO CORRECT FOR CLOSE PROX OF THE 2 ACFT.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.