Narrative:

We were cruising at FL310 and tracking sbound on J128 to lax at about 120 mi south of pgs VOR. We were asked if we could slow to 230 KTS. After checking the charts, it was determined that we could do it at a lower altitude. ATC was informed, and we were assigned FL280, 230 KTS. A few mins later we were instructed to descend to 14000 ft and during our descent we were instructed to maintain 250 KTS and 230 degree heading. A few mins later we were asked to increase our speed to 280 KTS and 230 degree heading. A couple mins later we were instructed to tune the runway 25L localizer and track it inbound. Couple of mins later we were instructed to maintain 14000 ft, 230 degrees and cleared the civet arrival. We tuned in 109.9 for runway 25L lax and our DME read 65 mi. The localizer and GS flags disappeared and the GS was alive. We had a weak but readable identify. At 54 mi we were leaving 17000 ft and had not yet intercepted the localizer. I requested our location in relation to the localizer from ATC and was informed that we were 1 mi east of the localizer. We had no flags on either #1 navigation or #2 navigation. We were now showing high on the GS and going higher. We were still at 14000 ft, our DME was now reading 27 mi. I asked ATC again our position and was informed that we would be intercepting well inside of civet and that we were about 1 mi east of the localizer. All the time that this was going on the ATC system was reaching overload and the controller was asking for everyone to stand by. With all this and the traffic, etc, we decided that we would have to start down or we would not be able to get down in time for a normal approach. We descended to 12000 ft between layers day VFR and stopped our descent to prevent going into the clouds without positive identify of our localizer. After about 3 mins at 12000 ft, ATC asked us if we were still at 14000 ft. I responded that we were at 12000 ft. ATC stated that he wanted us to climb now back to 14000 ft, that we were over big bear, and that the terrain minimum was 13500 ft MSL. We complied and I apologized for the error. The controller stated, 'no problem, I was just concerned about your altitude and position.' (he must have been looking at another aircraft when he gave us our position earlier.) in an attempt to find out what was wrong I re-channeled our navs and a few seconds later our DME now read 64 DME and the localizer was now alive and I could see outside that our position in relationship to the city and the airport locale -- we must have been at least 10 mi east of the localizer earlier to have been over big bear. We continued our approach and landing without further incident. I believe that in the interest of trying to help ATC because of the heavy traffic and the misinfo on our position from ATC and erroneous information on our navs that we did something under pressure to perform that could have been deadly (a lesson well learned on our part to back up the localizer with VOR information when available). I feel that the frequencys used in approaching lax, plus the constant speed, heading, and altitude changes is causing an ATC overload and they are at times unable to properly do their job. Many times because of the congested frequencys we do not get all of the information that is issued in a timely manner that allows you to confirm the request, and sometimes what you thought you heard or responded to, was not responded to, was not exactly what they intended. Due to the traffic, ATC as well as the flcs are missing information back and forth. I sincerely regret having made this error, and I am thankful that it did not end in a tragedy.

Related reports:

Google
 

Original NASA ASRS Text

Title: A DC8 FLC WAS GIVEN INSTRUCTIONS TO INTERCEPT THE CIVET ARR. ERRONEOUS DME AND GS INDICATIONS AND MISCOM WITH THE CTLR LED THEM TO DSND EARLY, IN VFR CONDITIONS, TO FOLLOW NAV INFO. ARTCC RADAR CTLR INTERVENED. ALTDEV ALT OVERSHOT.

Narrative: WE WERE CRUISING AT FL310 AND TRACKING SBOUND ON J128 TO LAX AT ABOUT 120 MI S OF PGS VOR. WE WERE ASKED IF WE COULD SLOW TO 230 KTS. AFTER CHKING THE CHARTS, IT WAS DETERMINED THAT WE COULD DO IT AT A LOWER ALT. ATC WAS INFORMED, AND WE WERE ASSIGNED FL280, 230 KTS. A FEW MINS LATER WE WERE INSTRUCTED TO DSND TO 14000 FT AND DURING OUR DSCNT WE WERE INSTRUCTED TO MAINTAIN 250 KTS AND 230 DEG HDG. A FEW MINS LATER WE WERE ASKED TO INCREASE OUR SPD TO 280 KTS AND 230 DEG HDG. A COUPLE MINS LATER WE WERE INSTRUCTED TO TUNE THE RWY 25L LOC AND TRACK IT INBOUND. COUPLE OF MINS LATER WE WERE INSTRUCTED TO MAINTAIN 14000 FT, 230 DEGS AND CLRED THE CIVET ARR. WE TUNED IN 109.9 FOR RWY 25L LAX AND OUR DME READ 65 MI. THE LOC AND GS FLAGS DISAPPEARED AND THE GS WAS ALIVE. WE HAD A WEAK BUT READABLE IDENT. AT 54 MI WE WERE LEAVING 17000 FT AND HAD NOT YET INTERCEPTED THE LOC. I REQUESTED OUR LOCATION IN RELATION TO THE LOC FROM ATC AND WAS INFORMED THAT WE WERE 1 MI E OF THE LOC. WE HAD NO FLAGS ON EITHER #1 NAV OR #2 NAV. WE WERE NOW SHOWING HIGH ON THE GS AND GOING HIGHER. WE WERE STILL AT 14000 FT, OUR DME WAS NOW READING 27 MI. I ASKED ATC AGAIN OUR POS AND WAS INFORMED THAT WE WOULD BE INTERCEPTING WELL INSIDE OF CIVET AND THAT WE WERE ABOUT 1 MI E OF THE LOC. ALL THE TIME THAT THIS WAS GOING ON THE ATC SYS WAS REACHING OVERLOAD AND THE CTLR WAS ASKING FOR EVERYONE TO STAND BY. WITH ALL THIS AND THE TFC, ETC, WE DECIDED THAT WE WOULD HAVE TO START DOWN OR WE WOULD NOT BE ABLE TO GET DOWN IN TIME FOR A NORMAL APCH. WE DSNDED TO 12000 FT BTWN LAYERS DAY VFR AND STOPPED OUR DSCNT TO PREVENT GOING INTO THE CLOUDS WITHOUT POSITIVE IDENT OF OUR LOC. AFTER ABOUT 3 MINS AT 12000 FT, ATC ASKED US IF WE WERE STILL AT 14000 FT. I RESPONDED THAT WE WERE AT 12000 FT. ATC STATED THAT HE WANTED US TO CLB NOW BACK TO 14000 FT, THAT WE WERE OVER BIG BEAR, AND THAT THE TERRAIN MINIMUM WAS 13500 FT MSL. WE COMPLIED AND I APOLOGIZED FOR THE ERROR. THE CTLR STATED, 'NO PROB, I WAS JUST CONCERNED ABOUT YOUR ALT AND POS.' (HE MUST HAVE BEEN LOOKING AT ANOTHER ACFT WHEN HE GAVE US OUR POS EARLIER.) IN AN ATTEMPT TO FIND OUT WHAT WAS WRONG I RE-CHANNELED OUR NAVS AND A FEW SECONDS LATER OUR DME NOW READ 64 DME AND THE LOC WAS NOW ALIVE AND I COULD SEE OUTSIDE THAT OUR POS IN RELATIONSHIP TO THE CITY AND THE ARPT LOCALE -- WE MUST HAVE BEEN AT LEAST 10 MI E OF THE LOC EARLIER TO HAVE BEEN OVER BIG BEAR. WE CONTINUED OUR APCH AND LNDG WITHOUT FURTHER INCIDENT. I BELIEVE THAT IN THE INTEREST OF TRYING TO HELP ATC BECAUSE OF THE HVY TFC AND THE MISINFO ON OUR POS FROM ATC AND ERRONEOUS INFO ON OUR NAVS THAT WE DID SOMETHING UNDER PRESSURE TO PERFORM THAT COULD HAVE BEEN DEADLY (A LESSON WELL LEARNED ON OUR PART TO BACK UP THE LOC WITH VOR INFO WHEN AVAILABLE). I FEEL THAT THE FREQS USED IN APCHING LAX, PLUS THE CONSTANT SPD, HDG, AND ALT CHANGES IS CAUSING AN ATC OVERLOAD AND THEY ARE AT TIMES UNABLE TO PROPERLY DO THEIR JOB. MANY TIMES BECAUSE OF THE CONGESTED FREQS WE DO NOT GET ALL OF THE INFO THAT IS ISSUED IN A TIMELY MANNER THAT ALLOWS YOU TO CONFIRM THE REQUEST, AND SOMETIMES WHAT YOU THOUGHT YOU HEARD OR RESPONDED TO, WAS NOT RESPONDED TO, WAS NOT EXACTLY WHAT THEY INTENDED. DUE TO THE TFC, ATC AS WELL AS THE FLCS ARE MISSING INFO BACK AND FORTH. I SINCERELY REGRET HAVING MADE THIS ERROR, AND I AM THANKFUL THAT IT DID NOT END IN A TRAGEDY.

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.