Narrative:

On descent into lax on the SADDE4 arrival I received a TCASII alert of traffic at 11 O'clock. I was descending through FL180. Immediately following the TA on the TCASII I received an RA of descent. I immediately deployed speed brakes and banked to the right. My first officer called traffic at 11 O'clock and it passed overhead shortly thereafter. I did see the traffic as we passed through his altitude. I was never issued a TA from the ATC controller (ZLA) until the traffic had passed overhead.

Google
 

Original NASA ASRS Text

Title: CLOSE PROX TFC ISSUED BY TCASII RA, OPPOSITE DIRECTION DSNDING TFC.

Narrative: ON DSCNT INTO LAX ON THE SADDE4 ARR I RECEIVED A TCASII ALERT OF TFC AT 11 O'CLOCK. I WAS DSNDING THROUGH FL180. IMMEDIATELY FOLLOWING THE TA ON THE TCASII I RECEIVED AN RA OF DSCNT. I IMMEDIATELY DEPLOYED SPD BRAKES AND BANKED TO THE R. MY FO CALLED TFC AT 11 O'CLOCK AND IT PASSED OVERHEAD SHORTLY THEREAFTER. I DID SEE THE TFC AS WE PASSED THROUGH HIS ALT. I WAS NEVER ISSUED A TA FROM THE ATC CTLR (ZLA) UNTIL THE TFC HAD PASSED OVERHEAD.

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.