Narrative:

I was cleared by approach to follow air carrier a to the airport. Air carrier Z was cleared to 25L and I was cleared for a visual to 25R. I was on tower frequency on final approach heading 250 degree near limma when another airplane was sighted thru the first officer sliding window heading about 140 degree. I was alerted by the second officer and only saw the airplane briefly for a few seconds at a higher altitude and turning eastbound before disappearing from view. I determined a safe separation existed to continue descending for a normal landing on 25R. The first officer observed the airplane passing from view above and behind us. We were surprised by the sudden sighting because ATC did not advise of any other traffic. I reported a near miss to lax tower controller xa by telephone and my company duty dispatch manager. A subsequent telephone call to controller xa confirmed the other airplane was an air carrier B widebody transport Z and according to the tower tapes all procedures were correctly followed. Air carrier B was given a visual approach with the responsibility to maintain visual separation but may not have allowed enough spacing or mistakenly sighted air carrier a instead of my airplane. Air carrier B widebody transport Z may have seen my airplane and was maneuvering to pass over and behind but due to the close proximity at night gave an illusion the aircraft were closer than they actually were.

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Original NASA ASRS Text

Title: POSSIBLE NMAC BETWEEN ACR LGT ON VISUAL APCH AND ACR WDB MANEUVERING TO FOLLOW.

Narrative: I WAS CLRED BY APCH TO FOLLOW ACR A TO THE ARPT. ACR Z WAS CLRED TO 25L AND I WAS CLRED FOR A VISUAL TO 25R. I WAS ON TWR FREQ ON FINAL APCH HDG 250 DEG NEAR LIMMA WHEN ANOTHER AIRPLANE WAS SIGHTED THRU THE F/O SLIDING WINDOW HDG ABOUT 140 DEG. I WAS ALERTED BY THE S/O AND ONLY SAW THE AIRPLANE BRIEFLY FOR A FEW SECONDS AT A HIGHER ALT AND TURNING EBND BEFORE DISAPPEARING FROM VIEW. I DETERMINED A SAFE SEPARATION EXISTED TO CONTINUE DESCENDING FOR A NORMAL LNDG ON 25R. THE F/O OBSERVED THE AIRPLANE PASSING FROM VIEW ABOVE AND BEHIND US. WE WERE SURPRISED BY THE SUDDEN SIGHTING BECAUSE ATC DID NOT ADVISE OF ANY OTHER TFC. I REPORTED A NEAR MISS TO LAX TWR CTLR XA BY TELEPHONE AND MY COMPANY DUTY DISPATCH MGR. A SUBSEQUENT TELEPHONE CALL TO CTLR XA CONFIRMED THE OTHER AIRPLANE WAS AN ACR B WDB Z AND ACCORDING TO THE TWR TAPES ALL PROCS WERE CORRECTLY FOLLOWED. ACR B WAS GIVEN A VISUAL APCH WITH THE RESPONSIBILITY TO MAINTAIN VISUAL SEPARATION BUT MAY NOT HAVE ALLOWED ENOUGH SPACING OR MISTAKENLY SIGHTED ACR A INSTEAD OF MY AIRPLANE. ACR B WDB Z MAY HAVE SEEN MY AIRPLANE AND WAS MANEUVERING TO PASS OVER AND BEHIND BUT DUE TO THE CLOSE PROX AT NIGHT GAVE AN ILLUSION THE ACFT WERE CLOSER THAN THEY ACTUALLY WERE.

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.