Narrative:

We were cleared for an ILS to lax runway 25L. About 25 mi out, the WX was clear with visibility of 7 mi. We were landing to the west into the sun and the true flight visibility was about 3 mi with heavy smog from the ground to 1500 ft MSL. The visibility above 1500 ft MSL was 50 mi. We were given traffic (a saab) about 5 mi to the south by socal approach. We had him in sight the whole time. He was cleared for a visual approach to runway 25L to follow us. He said he had us in sight. We were then cleared for a side-step approach to runway 25. The minimums for side-step runway 25R are 1 1/2 mi and 660 ft MSL. We thought that would be easy. We thought we would have runway 25R in sight by the lima OM about 7 mi out and then we could slide over to the right. The saab came in close on our left (about 100 yards) as I was on the runway 25L localizer, at our altitude. We flew formation for about 2 mi. I thought he would stay on our left until we moved over to the right when we had runway 25R in sight. About 8 mi out, the saab pulled ahead a little and seemed to lose sight of us (visibility 50 mi) and then moved over to the right directly in front of us on the runway 25L localizer about 50 yards ahead of us and we were forced to move over to the right about 100 yards and off the runway 25L localizer long before we had runway 25R in sight. This happened at about the OM. I was forced to the right, the TCASII was sounding. We could not go too much further to the right because of runway 24 traffic. I could not go down or up or left. I could not slow as I was at approach speed (160 KTS). I was afraid the saab would slow and we would have a midair. I stayed in formation on the saab about 100 yards to the right until we had runway 25R in sight. We could not use the localizer and we did not have runway 25R until about 3 mi out. I do not know why the saab lost sight of us and did not follow us. WX was not as given on ATIS.

Related reports:

Google
 

Original NASA ASRS Text

Title: NMAC OCCURS AS PIC OF SAAB SF340 FAILS TO MAINTAIN A VISUAL ON MD11 THAT HE IS SUPPOSED TO FOLLOW TO RWY 25L AT LAX. MD11 WAS CLRED FOR A SIDE-STEP TO RWY 25R.

Narrative: WE WERE CLRED FOR AN ILS TO LAX RWY 25L. ABOUT 25 MI OUT, THE WX WAS CLR WITH VISIBILITY OF 7 MI. WE WERE LNDG TO THE W INTO THE SUN AND THE TRUE FLT VISIBILITY WAS ABOUT 3 MI WITH HVY SMOG FROM THE GND TO 1500 FT MSL. THE VISIBILITY ABOVE 1500 FT MSL WAS 50 MI. WE WERE GIVEN TFC (A SAAB) ABOUT 5 MI TO THE S BY SOCAL APCH. WE HAD HIM IN SIGHT THE WHOLE TIME. HE WAS CLRED FOR A VISUAL APCH TO RWY 25L TO FOLLOW US. HE SAID HE HAD US IN SIGHT. WE WERE THEN CLRED FOR A SIDE-STEP APCH TO RWY 25. THE MINIMUMS FOR SIDE-STEP RWY 25R ARE 1 1/2 MI AND 660 FT MSL. WE THOUGHT THAT WOULD BE EASY. WE THOUGHT WE WOULD HAVE RWY 25R IN SIGHT BY THE LIMA OM ABOUT 7 MI OUT AND THEN WE COULD SLIDE OVER TO THE R. THE SAAB CAME IN CLOSE ON OUR L (ABOUT 100 YARDS) AS I WAS ON THE RWY 25L LOC, AT OUR ALT. WE FLEW FORMATION FOR ABOUT 2 MI. I THOUGHT HE WOULD STAY ON OUR L UNTIL WE MOVED OVER TO THE R WHEN WE HAD RWY 25R IN SIGHT. ABOUT 8 MI OUT, THE SAAB PULLED AHEAD A LITTLE AND SEEMED TO LOSE SIGHT OF US (VISIBILITY 50 MI) AND THEN MOVED OVER TO THE R DIRECTLY IN FRONT OF US ON THE RWY 25L LOC ABOUT 50 YARDS AHEAD OF US AND WE WERE FORCED TO MOVE OVER TO THE R ABOUT 100 YARDS AND OFF THE RWY 25L LOC LONG BEFORE WE HAD RWY 25R IN SIGHT. THIS HAPPENED AT ABOUT THE OM. I WAS FORCED TO THE R, THE TCASII WAS SOUNDING. WE COULD NOT GO TOO MUCH FURTHER TO THE R BECAUSE OF RWY 24 TFC. I COULD NOT GO DOWN OR UP OR L. I COULD NOT SLOW AS I WAS AT APCH SPD (160 KTS). I WAS AFRAID THE SAAB WOULD SLOW AND WE WOULD HAVE A MIDAIR. I STAYED IN FORMATION ON THE SAAB ABOUT 100 YARDS TO THE R UNTIL WE HAD RWY 25R IN SIGHT. WE COULD NOT USE THE LOC AND WE DID NOT HAVE RWY 25R UNTIL ABOUT 3 MI OUT. I DO NOT KNOW WHY THE SAAB LOST SIGHT OF US AND DID NOT FOLLOW US. WX WAS NOT AS GIVEN ON ATIS.

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.