Narrative:

We were cleared after smo fly heading 065 degrees expect radar vectors runway 24R. At about 10 DME smo we were switched to runway 24L, turn right heading 160 degrees. Approach then gave us turn right heading 220 degrees cleared for ILS runway 24L, etc. I set the heading bug then switched navigation mode from heading to ILS and got an instrument comparator warning. Looking across, I noted that the first officer's navigation was still on frequency 108.5. I told him to retune to 111.7 for runway 24L. Back to my side, my CDI was now showing almost 1.5 dots left of course, and the autoplt had not started the turn. This seemed a little strange but I have often had to override the autoplt to avoid an overshoot due to high speed close-in turns to these runways. I disconnected the autoplt, started correcting, checked for flags (none), crosschecked the first officer's instruments (they agreed now) and looked for the airport. We switched to tower. They said we were well right of course. We were now showing almost 2 dots left of course, no flags. I turned left heading 220 degrees and asked if we were getting a good identify. Both first officer and flight engineer said yes. We spotted the approach lights for runway 25L and I continued toward them, still looking for the north complex. We got visual with runway 24L inside sutie. The CDI was at full right deflection until we crossed the runway extended centerline to the south, at which time the CDI started indicating normally. The GS needle remained full up throughout. I established a normal visual approach by 1000 ft and landed normally. After block-in I called the supervisor. He said that there were no equipment warnings or complaints from other aircraft from that time. All his system appeared to be normal. It has always bothered me that we often get a last min runway change, sometimes several, going into lax. Another personal complaint is that the north complex is hard to find (visually) until lined up and close in. Callback conversation with reporter revealed the following information: no problems were detected in the airborne system upon inspection by maintenance. Although he did specifically ask for and received confirmation of the ILS identify from the first officer and so, he stated that when he personally selected the frequency he initially heard only static. This reinforced the conjecture regarding at least a temporary anomalous condition for the ILS transmitter. He further reinforced the fact that although they were technically VMC they were unable to see the runway from their position outside of the FAF.

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Original NASA ASRS Text

Title: B747-200 ON ILS APCH TO RWY 24L AT LAX ENCOUNTERS REVERSED LOC DISPLAY PRIOR TO INTERCEPT. MYSTERIOUSLY CORRECTS ITSELF WHEN ON COURSE.

Narrative: WE WERE CLRED AFTER SMO FLY HDG 065 DEGS EXPECT RADAR VECTORS RWY 24R. AT ABOUT 10 DME SMO WE WERE SWITCHED TO RWY 24L, TURN R HDG 160 DEGS. APCH THEN GAVE US TURN R HDG 220 DEGS CLRED FOR ILS RWY 24L, ETC. I SET THE HDG BUG THEN SWITCHED NAV MODE FROM HDG TO ILS AND GOT AN INST COMPARATOR WARNING. LOOKING ACROSS, I NOTED THAT THE FO'S NAV WAS STILL ON FREQ 108.5. I TOLD HIM TO RETUNE TO 111.7 FOR RWY 24L. BACK TO MY SIDE, MY CDI WAS NOW SHOWING ALMOST 1.5 DOTS L OF COURSE, AND THE AUTOPLT HAD NOT STARTED THE TURN. THIS SEEMED A LITTLE STRANGE BUT I HAVE OFTEN HAD TO OVERRIDE THE AUTOPLT TO AVOID AN OVERSHOOT DUE TO HIGH SPD CLOSE-IN TURNS TO THESE RWYS. I DISCONNECTED THE AUTOPLT, STARTED CORRECTING, CHKED FOR FLAGS (NONE), XCHKED THE FO'S INSTS (THEY AGREED NOW) AND LOOKED FOR THE ARPT. WE SWITCHED TO TWR. THEY SAID WE WERE WELL R OF COURSE. WE WERE NOW SHOWING ALMOST 2 DOTS L OF COURSE, NO FLAGS. I TURNED L HDG 220 DEGS AND ASKED IF WE WERE GETTING A GOOD IDENT. BOTH FO AND FE SAID YES. WE SPOTTED THE APCH LIGHTS FOR RWY 25L AND I CONTINUED TOWARD THEM, STILL LOOKING FOR THE N COMPLEX. WE GOT VISUAL WITH RWY 24L INSIDE SUTIE. THE CDI WAS AT FULL R DEFLECTION UNTIL WE CROSSED THE RWY EXTENDED CTRLINE TO THE S, AT WHICH TIME THE CDI STARTED INDICATING NORMALLY. THE GS NEEDLE REMAINED FULL UP THROUGHOUT. I ESTABLISHED A NORMAL VISUAL APCH BY 1000 FT AND LANDED NORMALLY. AFTER BLOCK-IN I CALLED THE SUPVR. HE SAID THAT THERE WERE NO EQUIP WARNINGS OR COMPLAINTS FROM OTHER ACFT FROM THAT TIME. ALL HIS SYS APPEARED TO BE NORMAL. IT HAS ALWAYS BOTHERED ME THAT WE OFTEN GET A LAST MIN RWY CHANGE, SOMETIMES SEVERAL, GOING INTO LAX. ANOTHER PERSONAL COMPLAINT IS THAT THE N COMPLEX IS HARD TO FIND (VISUALLY) UNTIL LINED UP AND CLOSE IN. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: NO PROBS WERE DETECTED IN THE AIRBORNE SYS UPON INSPECTION BY MAINT. ALTHOUGH HE DID SPECIFICALLY ASK FOR AND RECEIVED CONFIRMATION OF THE ILS IDENT FROM THE FO AND SO, HE STATED THAT WHEN HE PERSONALLY SELECTED THE FREQ HE INITIALLY HEARD ONLY STATIC. THIS REINFORCED THE CONJECTURE REGARDING AT LEAST A TEMPORARY ANOMALOUS CONDITION FOR THE ILS XMITTER. HE FURTHER REINFORCED THE FACT THAT ALTHOUGH THEY WERE TECHNICALLY VMC THEY WERE UNABLE TO SEE THE RWY FROM THEIR POS OUTSIDE OF THE FAF.

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.