Narrative:

After reaching civet on the FMS and frm (from) civet was displayed, we began our descent to cross the next fix, bremr, at 12000 ft. After civet we also switched from FMS navigation to VOR/DME navigation utilizing the lax ILS/DME to runway 25L, per pilot's approach checklist which dictates that radio/navigation switches be placed in the radio position. As the lax ILS/DME frequency was being tuned and idented, ATC informed us that their radar showed that we were not yet at civet and had begun our descent prior to civet. After confirming our position with ATC, we determined that the FMS was in error at civet by approximately 4 mi. We confirmed that the latitude and longitude in the database were correct for civet and we made a maintenance logbook entry to this effect after arriving lax for maintenance troubleshooting of this FMS problem. Also, all 3 crew members verified that we had indeed passed civet on the FMS display and were now en route to bremr. We received no TCASII alerts and were in VMC. The balance of the arrival, approach, and landing on runway 25L were normal. The problem: as the L1011 ages, more problems like this will appear and special attention must be given to not only the navigation system but to all the maintenance concerns of an older aircraft.

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Original NASA ASRS Text

Title: AN ACR FLC ON AN L1011 STARTS THEIR DSCNT EARLY AT CIVET WHEN THEY REF THEIR FMS ONLY, WITHOUT USING AVAILABLE VOR AND DME RAW DATA. FLC STATES THAT THEY FOLLOWED COMPANY PROC AND THEY THEN COMPLAIN ABOUT AGING ACFT.

Narrative: AFTER REACHING CIVET ON THE FMS AND FRM (FROM) CIVET WAS DISPLAYED, WE BEGAN OUR DSCNT TO CROSS THE NEXT FIX, BREMR, AT 12000 FT. AFTER CIVET WE ALSO SWITCHED FROM FMS NAV TO VOR/DME NAV UTILIZING THE LAX ILS/DME TO RWY 25L, PER PLT'S APCH CHKLIST WHICH DICTATES THAT RADIO/NAV SWITCHES BE PLACED IN THE RADIO POS. AS THE LAX ILS/DME FREQ WAS BEING TUNED AND IDENTED, ATC INFORMED US THAT THEIR RADAR SHOWED THAT WE WERE NOT YET AT CIVET AND HAD BEGUN OUR DSCNT PRIOR TO CIVET. AFTER CONFIRMING OUR POS WITH ATC, WE DETERMINED THAT THE FMS WAS IN ERROR AT CIVET BY APPROX 4 MI. WE CONFIRMED THAT THE LATITUDE AND LONGITUDE IN THE DATABASE WERE CORRECT FOR CIVET AND WE MADE A MAINT LOGBOOK ENTRY TO THIS EFFECT AFTER ARRIVING LAX FOR MAINT TROUBLESHOOTING OF THIS FMS PROB. ALSO, ALL 3 CREW MEMBERS VERIFIED THAT WE HAD INDEED PASSED CIVET ON THE FMS DISPLAY AND WERE NOW ENRTE TO BREMR. WE RECEIVED NO TCASII ALERTS AND WERE IN VMC. THE BAL OF THE ARR, APCH, AND LNDG ON RWY 25L WERE NORMAL. THE PROB: AS THE L1011 AGES, MORE PROBS LIKE THIS WILL APPEAR AND SPECIAL ATTN MUST BE GIVEN TO NOT ONLY THE NAV SYS BUT TO ALL THE MAINT CONCERNS OF AN OLDER ACFT.

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.