Narrative:

First officer's leg from sjc to lax. WX was 6 mi visibility with haze, and no ceiling. We were given a heading of 070 degrees off of santa monica VOR, on the sadde 6 arrival. In our descent from 8000 ft to 5000 ft we were advised of a brasilia at 12 O'clock position and 4 mi. We had the aircraft in sight and were given a 'visual approach' and to follow the brasilia to runway 24R. We turned our base, began to configure and descend. We were also advised of a DC10 going to runway 25L. We had this aircraft in sight during the entire approach. On our modified base to final we momentarily lost sight of the brasilia, but did pick up the airport visually. Having the DC10, and the airport in sight, we checked on with lax tower. We were instructed to 'continue.' upon my captain's reading of the checklist, 3 events happened simultaneously: 1) when asked 'flight and navigation instruments' on the checklist, we both realized that we had flown through the localizer. 2) we now saw the north complex and realize that we were angling in towards the south complex. 3) tower asked us if we had 'runway 24R in sight, because it appears that you were looking at runway 25L/right.' by then, we were already turning back to reintercept runway 24R, which we did above 1000 ft AGL. At 1000 ft AGL we were on localizer, on GS, configured and made an uneventful landing on runway 24R. We were cleared to land once we assured tower that we were turning back to intercept runway 24R. Tower made no more mention of this and we taxied in to the terminal. 2 mistakes that we made: 1) do not accept a visual when following an aircraft and not having the airport unless you are certain that you can maintain a good visual. It is much easier to lose sight of an aircraft (like a small brasilia) than it is to lose sight of an airport. 2) we should not have let the task of maintaining all of these visual queues (DC10, brasilia, lax) interfere with flying the aircraft for just a few seconds, we 'went outside' and let the localizer go unnoticed. We were quick to correct our mistakes, but you can see how these events, gone unnoticed, could have resulted in a TA or RA and probably a missed approach!

Related reports:

Google
 

Original NASA ASRS Text

Title: B737-300 CREW OVERSHOT THE TURN TO THE N COMPLEX AT LAX, WHILE ATTEMPTING TO KEEP S COMPLEX TFC AND TFC THEY WERE TO FOLLOW IN SIGHT.

Narrative: FO'S LEG FROM SJC TO LAX. WX WAS 6 MI VISIBILITY WITH HAZE, AND NO CEILING. WE WERE GIVEN A HDG OF 070 DEGS OFF OF SANTA MONICA VOR, ON THE SADDE 6 ARR. IN OUR DSCNT FROM 8000 FT TO 5000 FT WE WERE ADVISED OF A BRASILIA AT 12 O'CLOCK POS AND 4 MI. WE HAD THE ACFT IN SIGHT AND WERE GIVEN A 'VISUAL APCH' AND TO FOLLOW THE BRASILIA TO RWY 24R. WE TURNED OUR BASE, BEGAN TO CONFIGURE AND DSND. WE WERE ALSO ADVISED OF A DC10 GOING TO RWY 25L. WE HAD THIS ACFT IN SIGHT DURING THE ENTIRE APCH. ON OUR MODIFIED BASE TO FINAL WE MOMENTARILY LOST SIGHT OF THE BRASILIA, BUT DID PICK UP THE ARPT VISUALLY. HAVING THE DC10, AND THE ARPT IN SIGHT, WE CHKED ON WITH LAX TWR. WE WERE INSTRUCTED TO 'CONTINUE.' UPON MY CAPT'S READING OF THE CHKLIST, 3 EVENTS HAPPENED SIMULTANEOUSLY: 1) WHEN ASKED 'FLT AND NAV INSTS' ON THE CHKLIST, WE BOTH REALIZED THAT WE HAD FLOWN THROUGH THE LOC. 2) WE NOW SAW THE N COMPLEX AND REALIZE THAT WE WERE ANGLING IN TOWARDS THE S COMPLEX. 3) TWR ASKED US IF WE HAD 'RWY 24R IN SIGHT, BECAUSE IT APPEARS THAT YOU WERE LOOKING AT RWY 25L/R.' BY THEN, WE WERE ALREADY TURNING BACK TO REINTERCEPT RWY 24R, WHICH WE DID ABOVE 1000 FT AGL. AT 1000 FT AGL WE WERE ON LOC, ON GS, CONFIGURED AND MADE AN UNEVENTFUL LNDG ON RWY 24R. WE WERE CLRED TO LAND ONCE WE ASSURED TWR THAT WE WERE TURNING BACK TO INTERCEPT RWY 24R. TWR MADE NO MORE MENTION OF THIS AND WE TAXIED IN TO THE TERMINAL. 2 MISTAKES THAT WE MADE: 1) DO NOT ACCEPT A VISUAL WHEN FOLLOWING AN ACFT AND NOT HAVING THE ARPT UNLESS YOU ARE CERTAIN THAT YOU CAN MAINTAIN A GOOD VISUAL. IT IS MUCH EASIER TO LOSE SIGHT OF AN ACFT (LIKE A SMALL BRASILIA) THAN IT IS TO LOSE SIGHT OF AN ARPT. 2) WE SHOULD NOT HAVE LET THE TASK OF MAINTAINING ALL OF THESE VISUAL QUEUES (DC10, BRASILIA, LAX) INTERFERE WITH FLYING THE ACFT FOR JUST A FEW SECONDS, WE 'WENT OUTSIDE' AND LET THE LOC GO UNNOTICED. WE WERE QUICK TO CORRECT OUR MISTAKES, BUT YOU CAN SEE HOW THESE EVENTS, GONE UNNOTICED, COULD HAVE RESULTED IN A TA OR RA AND PROBABLY A MISSED APCH!

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.