Narrative:

Cleared for visual approach behind preceding traffic on ILS to runway 25L at lax. Approach calls additional traffic to join up on our right for runway 25R. We report that aircraft not in sight. Approach tells us it is alright, he has us in sight and will maintain visual separation. Kept searching -- not in sight. Captain (PF) established a DOT to DOT 1/2 left of localizer centerline to provide additional lateral separation from runway 25R localizer. Just outside limma intersection we got a TCASII TA. Aircraft symbol was directly above us (I think 700 ft). I looked and could not see the saab. Shortly thereafter, we got a TCASII RA 'descend, descend.' captain increased rate of descent. I still could not see the saab. Moments later, I saw the saab for the first time, out my right side window, almost directly above us drifting away to the right. We were still 1 DOT left of localizer centerline. I asked tower (we switched at FAF to tower) to confirm that the saab was landing on runway 25R as it appeared he was closer to the runway 25L localizer centerline than we were. Tower confirmed. Additional factors; change of landing runway assignment late on arrival requiring heads down time to reprogram FMC. Playing catch-up (due to change of runway) with descent and approach checklist, cabin notification, tuning and identing new ILS frequency, etc. Event happened after all this was accomplished, but still in doublechk mode to insure all was correct after last min change. Less time available to be aware of other aircraft which might become a factor to our arrival.

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Original NASA ASRS Text

Title: B757-200 AND SF34 HAD NMAC FLYING APCHS TO THE S COMPLEX IN LAX CLASS B AIRSPACE.

Narrative: CLRED FOR VISUAL APCH BEHIND PRECEDING TFC ON ILS TO RWY 25L AT LAX. APCH CALLS ADDITIONAL TFC TO JOIN UP ON OUR R FOR RWY 25R. WE RPT THAT ACFT NOT IN SIGHT. APCH TELLS US IT IS ALRIGHT, HE HAS US IN SIGHT AND WILL MAINTAIN VISUAL SEPARATION. KEPT SEARCHING -- NOT IN SIGHT. CAPT (PF) ESTABLISHED A DOT TO DOT 1/2 L OF LOC CTRLINE TO PROVIDE ADDITIONAL LATERAL SEPARATION FROM RWY 25R LOC. JUST OUTSIDE LIMMA INTXN WE GOT A TCASII TA. ACFT SYMBOL WAS DIRECTLY ABOVE US (I THINK 700 FT). I LOOKED AND COULD NOT SEE THE SAAB. SHORTLY THEREAFTER, WE GOT A TCASII RA 'DSND, DSND.' CAPT INCREASED RATE OF DSCNT. I STILL COULD NOT SEE THE SAAB. MOMENTS LATER, I SAW THE SAAB FOR THE FIRST TIME, OUT MY R SIDE WINDOW, ALMOST DIRECTLY ABOVE US DRIFTING AWAY TO THE R. WE WERE STILL 1 DOT L OF LOC CTRLINE. I ASKED TWR (WE SWITCHED AT FAF TO TWR) TO CONFIRM THAT THE SAAB WAS LNDG ON RWY 25R AS IT APPEARED HE WAS CLOSER TO THE RWY 25L LOC CTRLINE THAN WE WERE. TWR CONFIRMED. ADDITIONAL FACTORS; CHANGE OF LNDG RWY ASSIGNMENT LATE ON ARR REQUIRING HEADS DOWN TIME TO REPROGRAM FMC. PLAYING CATCH-UP (DUE TO CHANGE OF RWY) WITH DSCNT AND APCH CHKLIST, CABIN NOTIFICATION, TUNING AND IDENTING NEW ILS FREQ, ETC. EVENT HAPPENED AFTER ALL THIS WAS ACCOMPLISHED, BUT STILL IN DOUBLECHK MODE TO INSURE ALL WAS CORRECT AFTER LAST MIN CHANGE. LESS TIME AVAILABLE TO BE AWARE OF OTHER ACFT WHICH MIGHT BECOME A FACTOR TO OUR ARR.

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.