MD-11
Flight Crew Flight Engineer; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 120; Flight Crew Total 9500; Flight Crew Type 2000
Conflict Airborne Conflict; Deviation - Altitude Excursion From Assigned Altitude
Flight Crew Took Evasive Action
Aircraft; Procedure
We were on a profile descent clearance for the SEAVU2 STAR to the ILS 25L at LAX. We had been assigned 210 KIAS by SCT Approach and were descending to make the 1;900 MSL crossing for glideslope intercept at the final approach point of LIMMA. Approaching HUNDA; SCT queried whether we had the airport. Due to the setting sun it was not initially visible; but we acquired it shortly after the query and called the field in sight. SCT cleared us for the visual; told us to maintain at least 180 KIAS to five mile final; advised us we were following heavy B-747 traffic ahead (about 7 miles on TCAS) and advised us of converging traffic to the north which was going to the north complex. Traffic we were following was not in sight (TCAS traffic ahead) but I did see parallel traffic to our north about two miles which I assumed was the north complex traffic (again correlated with TCAS presentation). I did not call visual on any traffic; only acknowledging the calls from Approach. SCT cleared us for the visual approach and told us to contact Tower. We switched to Tower and checked in; but comm was busy. We were again advised of the traffic and cleared to land. Descending through about 2;100 MSL just prior to LIMMA as we were slowing through about 190 KIAS and configuring to land the TCAS called out 'TRAFFIC; TRAFFIC'. TCAS almost immediately went to 'CLIMB; CLIMB' command and I disconnected the autopilot and followed the guidance. As I initiated the maneuver the TCAS showed RA traffic slightly right and below and descending. I also saw 300 FT vertical separation as I started the maneuver and my First Officer eventually saw 100 FT. I reversed the 1;500 FPM rate of descent to comply with the RA and ended up climbing at about 1;200 FPM. Climbing back through about 2;100 MSL; TCAS called 'CLEAR OF TRAFFIC'. We were slightly inside of LIMMA at this point and about one dot above the glideslope. TCAS traffic was no longer evident and I elected to resume the previous clearance for the visual approach. Tower was advised at the earliest opportunity that we had responded to an RA. They advised us there was no radar traffic evident in our vicinity. We landed uneventfully and I called the Tower Supervisor to query him about the event. He advised that several aircraft had had similar experiences while on final recently.
An MD11 had a TCAS RA at 2;100 FT during visual approach to Runway 25L at LAX.  The Tower advised that there is no traffic in the vicinity and that other aircraft have had recent similar experiences.