B737-700
Flight Crew Last 90 Days 218; Flight Crew Type 3670
Conflict NMAC
Flight Crew FLC complied w / Automation / Advisory; Flight Crew Took Evasive Action
Human Factors
While being vectored to a visual approach to Runway 24R at LAX and approximately 9 DME from the runway; we received a TCAS RA for pop up traffic at our 10-11 o'clock. We were vectored to our base turn from downwind by ATC as they became aware of the traffic conflict. Our aircraft was passing 3;300 FT in a descent to 3;000 FT when the RA was received. We executed a TCAS avoidance procedures as described in the FOM; executing a level off to very slight climb in accordance with TCAS guidance. Audible 'Adjust Vertical Speed' was issued by the TCAS system. System showed the nearest point of separation to be 400 FT. ATC advised us that conflict aircraft was 'not supposed to be there' and was apparently not in contact with them.
[Narrative 2 contained no additional information.]
B737-700 experienced NMAC on downwind at LAX from an aircraft who was not talking to ATC.