Narrative:

On ILS approach runway 25L, lax, we were cleared for an ILS approach when we got to fueler. At fueler we were slowed to 180 KTS and advised of a widebody transport at 1 O'clock heading south to turn on 24L. We were advised of another aircraft from the south that would be crossing our path to 25R. We were told to slow to 160 KTS. We advised that we thought we had something at 11 O'clock. ATC told us to follow him. Shortly we were told to maintain 4000' because the widebody transport had overshot the 24L centerline. While at 4000' we saw the aircraft from the left for the first time! (We had something else in sight previously.) the aircraft was about 500' lower. We both saw each other about the same time because it looked like he took an evasive maneuver. (Right wing came up and he dropped faster, it seemed.) he passed under us and we lost sight of him as he moved under us. We were never cleared below 4000' until we called aircraft in close proximity. By then it was obvious we were out of position for a safe approach and we asked for a missed approach. It appeared that this situation could have been a near miss if we maintained profile instead of leveling at 4000' for aircraft on right. In the many lights in the visibility conditions at lax, we never had and never called a positive aircraft identify. We were boxed in by widebody transport on right and aircraft on left--a bad situation when we were at minimum approach speed. I was watching widebody transport on the right and captain looking for aircraft on left--the F/east trying to help up both sort out the lights. The situation occurred because the controller told another aircraft to cross over in front of us when we were both at similar speeds at night when speed and distance judgements are marginal at best. We later learned that controller training was in progress.

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Original NASA ASRS Text

Title: CLOSE PROX ACR-WDB UNK-ACR ON APCH TO LAX.

Narrative: ON ILS APCH RWY 25L, LAX, WE WERE CLRED FOR AN ILS APCH WHEN WE GOT TO FUELER. AT FUELER WE WERE SLOWED TO 180 KTS AND ADVISED OF A WDB AT 1 O'CLOCK HDG S TO TURN ON 24L. WE WERE ADVISED OF ANOTHER ACFT FROM THE S THAT WOULD BE XING OUR PATH TO 25R. WE WERE TOLD TO SLOW TO 160 KTS. WE ADVISED THAT WE THOUGHT WE HAD SOMETHING AT 11 O'CLOCK. ATC TOLD US TO FOLLOW HIM. SHORTLY WE WERE TOLD TO MAINTAIN 4000' BECAUSE THE WDB HAD OVERSHOT THE 24L CENTERLINE. WHILE AT 4000' WE SAW THE ACFT FROM THE LEFT FOR THE FIRST TIME! (WE HAD SOMETHING ELSE IN SIGHT PREVIOUSLY.) THE ACFT WAS ABOUT 500' LOWER. WE BOTH SAW EACH OTHER ABOUT THE SAME TIME BECAUSE IT LOOKED LIKE HE TOOK AN EVASIVE MANEUVER. (RIGHT WING CAME UP AND HE DROPPED FASTER, IT SEEMED.) HE PASSED UNDER US AND WE LOST SIGHT OF HIM AS HE MOVED UNDER US. WE WERE NEVER CLRED BELOW 4000' UNTIL WE CALLED ACFT IN CLOSE PROX. BY THEN IT WAS OBVIOUS WE WERE OUT OF POS FOR A SAFE APCH AND WE ASKED FOR A MISSED APCH. IT APPEARED THAT THIS SITUATION COULD HAVE BEEN A NEAR MISS IF WE MAINTAINED PROFILE INSTEAD OF LEVELING AT 4000' FOR ACFT ON RIGHT. IN THE MANY LIGHTS IN THE VIS CONDITIONS AT LAX, WE NEVER HAD AND NEVER CALLED A POSITIVE ACFT IDENT. WE WERE BOXED IN BY WDB ON RIGHT AND ACFT ON LEFT--A BAD SITUATION WHEN WE WERE AT MINIMUM APCH SPD. I WAS WATCHING WDB ON THE RIGHT AND CAPT LOOKING FOR ACFT ON LEFT--THE F/E TRYING TO HELP UP BOTH SORT OUT THE LIGHTS. THE SITUATION OCCURRED BECAUSE THE CTLR TOLD ANOTHER ACFT TO CROSS OVER IN FRONT OF US WHEN WE WERE BOTH AT SIMILAR SPDS AT NIGHT WHEN SPD AND DISTANCE JUDGEMENTS ARE MARGINAL AT BEST. WE LATER LEARNED THAT CTLR TRNING WAS IN PROGRESS.

Data retrieved from NASA's ASRS site as of August 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.