Narrative:

We departed smo VOR on heading of 070 degrees with instructions to descend to 2500 ft on this heading. We were told to follow a DC8 6 mi ahead for a visual to runway 24R. As the DC8 passed abeam us, we started a right base to follow him. During the turn the approach controller cleared us for the visual to runway 24L. A few seconds later, the controller assigned us a 220 degree heading to intercept the visual final for runway 24L. We saw parallel runways we assumed were runways 24L/right, which in reality were runways 25L/right. About that time we received a 'descend RA' from the TCASII, which we complied with. We realized our error as the controller assigned us a 280 degree heading to join final for runway 24L. The controller then told us of traffic above us. The rest of the approach was uneventful. Several factors contributed to the problem. First, we were cleared a visual approach following traffic to a runway with inoperative localizer and OM. Since the localizer was inoperative for our assigned runway, we had lax VOR tuned. The second problem was when the controller switched us over to runway 24L, we were outside of the visibility limits to see the complex. While we were trying to acquire runway 24L visually, we lost visual contact with the DC8. The controller then assigned the heading 220 degrees, and as we proceeded on the vector, we visually acquired runways 25L/right, which we mistook for runways 24L/right. This incident could have been prevented had the controller not assigned a visual approach before confirming that we had runway 24L in sight. Controllers must realize the difficulty in acquiring traffic/airport at night in the lax terminal area. Therefore, last min changes, combined with NAVAID outages, should be avoided. When it becomes obvious to the controller that an aircraft is deviating to the wrong complex at lax, a correction should be issued immediately. As for the crew, we should have tuned the localizer for runway 24L immediately upon receiving clearance for that runway instead of trying to acquire the runway by visual means.

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Original NASA ASRS Text

Title: DC10 CREW RECEIVES TCASII RA AFTER LOSING SIGHT OF TFC ON APCH TO LAX.

Narrative: WE DEPARTED SMO VOR ON HDG OF 070 DEGS WITH INSTRUCTIONS TO DSND TO 2500 FT ON THIS HDG. WE WERE TOLD TO FOLLOW A DC8 6 MI AHEAD FOR A VISUAL TO RWY 24R. AS THE DC8 PASSED ABEAM US, WE STARTED A R BASE TO FOLLOW HIM. DURING THE TURN THE APCH CTLR CLRED US FOR THE VISUAL TO RWY 24L. A FEW SECONDS LATER, THE CTLR ASSIGNED US A 220 DEG HDG TO INTERCEPT THE VISUAL FINAL FOR RWY 24L. WE SAW PARALLEL RWYS WE ASSUMED WERE RWYS 24L/R, WHICH IN REALITY WERE RWYS 25L/R. ABOUT THAT TIME WE RECEIVED A 'DSND RA' FROM THE TCASII, WHICH WE COMPLIED WITH. WE REALIZED OUR ERROR AS THE CTLR ASSIGNED US A 280 DEG HDG TO JOIN FINAL FOR RWY 24L. THE CTLR THEN TOLD US OF TFC ABOVE US. THE REST OF THE APCH WAS UNEVENTFUL. SEVERAL FACTORS CONTRIBUTED TO THE PROB. FIRST, WE WERE CLRED A VISUAL APCH FOLLOWING TFC TO A RWY WITH INOP LOC AND OM. SINCE THE LOC WAS INOP FOR OUR ASSIGNED RWY, WE HAD LAX VOR TUNED. THE SECOND PROB WAS WHEN THE CTLR SWITCHED US OVER TO RWY 24L, WE WERE OUTSIDE OF THE VISIBILITY LIMITS TO SEE THE COMPLEX. WHILE WE WERE TRYING TO ACQUIRE RWY 24L VISUALLY, WE LOST VISUAL CONTACT WITH THE DC8. THE CTLR THEN ASSIGNED THE HDG 220 DEGS, AND AS WE PROCEEDED ON THE VECTOR, WE VISUALLY ACQUIRED RWYS 25L/R, WHICH WE MISTOOK FOR RWYS 24L/R. THIS INCIDENT COULD HAVE BEEN PREVENTED HAD THE CTLR NOT ASSIGNED A VISUAL APCH BEFORE CONFIRMING THAT WE HAD RWY 24L IN SIGHT. CTLRS MUST REALIZE THE DIFFICULTY IN ACQUIRING TFC/ARPT AT NIGHT IN THE LAX TERMINAL AREA. THEREFORE, LAST MIN CHANGES, COMBINED WITH NAVAID OUTAGES, SHOULD BE AVOIDED. WHEN IT BECOMES OBVIOUS TO THE CTLR THAT AN ACFT IS DEVIATING TO THE WRONG COMPLEX AT LAX, A CORRECTION SHOULD BE ISSUED IMMEDIATELY. AS FOR THE CREW, WE SHOULD HAVE TUNED THE LOC FOR RWY 24L IMMEDIATELY UPON RECEIVING CLRNC FOR THAT RWY INSTEAD OF TRYING TO ACQUIRE THE RWY BY VISUAL MEANS.

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.