Narrative:

We briefed the civet 5 to runway 25R during cruise. During descent on the civet 5 approaching rustt we were given a clearance to descend via the civet 5 for runway 24R. The captain was PF and I as PNF selected 15000 ft in the MCP. I then proceeded to program the FMC for runway 24R. It was initially set up for runway 25R. We were approximately 1-2 mi from rustt and now showed a discontinuity on the FMC. The captain turned off the autoplt. I then told the captain we needed to go to manual with a 226 degree course to paradise VOR; which was set. As we were establishing ourselves on the course; both FMC's screens said 'FMC' at which time I requested a heading with socal and explained that we were having FMC problems. Socal gave us a heading of 260 degrees to join the runway 24R localizer. The controller gave us the localizer frequency of 108.5; which we set manually on both sides. VOR/localizer was armed and captured and we were given a descent to 10000 ft. There was a B737 joining the runway 25R localizer while we were showing VOR/localizer capture for runway 24R. The captain then turned to join the runway 24R localizer. The turn to track inbound on the runway 24R localizer pointed us toward the other B737 jet. I explained that we needed to come right; and the captain came right; once again the VOR/localizer showed capture with runway 24R frequency selected. The captain turned to track the runway 24R localizer again. ATC then asked us if we were set up for runway 24R; I responded that we had 108.5 selected. ATC then asked the other B737 to offset to the south. We then got a TCAS traffic alert followed by a monitor vertical speed RA. I then told the captain that we needed to come right as the localizer was erratic and appeared to be giving us false guidance. ATC then gave us a 290 degree heading and the captain turned to 290 degrees. I then looked at the course window and approach chart and notice that we still had the 226 degree course set. I then set both course windows to the 249 degree course for the localizer; and we were given a 250 degree heading to join runway 24R. We rearmed VOR/localizer and joined the runway 24R localizer and were given a descent to 7000 ft. We were then given a clearance for the ILS runway 24R and landed with no other events.

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Original NASA ASRS Text

Title: B737-300 FLT CREW HAS A TRACK AND HDG DEV DURING CIVET ARR TO LAX FOLLOWING DUAL FMC FAILURES.

Narrative: WE BRIEFED THE CIVET 5 TO RWY 25R DURING CRUISE. DURING DSCNT ON THE CIVET 5 APCHING RUSTT WE WERE GIVEN A CLRNC TO DSND VIA THE CIVET 5 FOR RWY 24R. THE CAPT WAS PF AND I AS PNF SELECTED 15000 FT IN THE MCP. I THEN PROCEEDED TO PROGRAM THE FMC FOR RWY 24R. IT WAS INITIALLY SET UP FOR RWY 25R. WE WERE APPROX 1-2 MI FROM RUSTT AND NOW SHOWED A DISCONTINUITY ON THE FMC. THE CAPT TURNED OFF THE AUTOPLT. I THEN TOLD THE CAPT WE NEEDED TO GO TO MANUAL WITH A 226 DEG COURSE TO PARADISE VOR; WHICH WAS SET. AS WE WERE ESTABLISHING OURSELVES ON THE COURSE; BOTH FMC'S SCREENS SAID 'FMC' AT WHICH TIME I REQUESTED A HDG WITH SOCAL AND EXPLAINED THAT WE WERE HAVING FMC PROBS. SOCAL GAVE US A HDG OF 260 DEGS TO JOIN THE RWY 24R LOC. THE CTLR GAVE US THE LOC FREQ OF 108.5; WHICH WE SET MANUALLY ON BOTH SIDES. VOR/LOC WAS ARMED AND CAPTURED AND WE WERE GIVEN A DSCNT TO 10000 FT. THERE WAS A B737 JOINING THE RWY 25R LOC WHILE WE WERE SHOWING VOR/LOC CAPTURE FOR RWY 24R. THE CAPT THEN TURNED TO JOIN THE RWY 24R LOC. THE TURN TO TRACK INBOUND ON THE RWY 24R LOC POINTED US TOWARD THE OTHER B737 JET. I EXPLAINED THAT WE NEEDED TO COME R; AND THE CAPT CAME R; ONCE AGAIN THE VOR/LOC SHOWED CAPTURE WITH RWY 24R FREQ SELECTED. THE CAPT TURNED TO TRACK THE RWY 24R LOC AGAIN. ATC THEN ASKED US IF WE WERE SET UP FOR RWY 24R; I RESPONDED THAT WE HAD 108.5 SELECTED. ATC THEN ASKED THE OTHER B737 TO OFFSET TO THE S. WE THEN GOT A TCAS TFC ALERT FOLLOWED BY A MONITOR VERT SPD RA. I THEN TOLD THE CAPT THAT WE NEEDED TO COME R AS THE LOC WAS ERRATIC AND APPEARED TO BE GIVING US FALSE GUIDANCE. ATC THEN GAVE US A 290 DEG HDG AND THE CAPT TURNED TO 290 DEGS. I THEN LOOKED AT THE COURSE WINDOW AND APCH CHART AND NOTICE THAT WE STILL HAD THE 226 DEG COURSE SET. I THEN SET BOTH COURSE WINDOWS TO THE 249 DEG COURSE FOR THE LOC; AND WE WERE GIVEN A 250 DEG HDG TO JOIN RWY 24R. WE REARMED VOR/LOC AND JOINED THE RWY 24R LOC AND WERE GIVEN A DSCNT TO 7000 FT. WE WERE THEN GIVEN A CLRNC FOR THE ILS RWY 24R AND LANDED WITH NO OTHER EVENTS.

Data retrieved from NASA's ASRS site as of January 2009 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.