Narrative:

Airline flight was en route from juneau, ak, to sitka, ak. Route of flight was juneau two departure, sisters island transition, ssr VOR V-431 to cluck intersection, lda DME runway 11 to sitka airport. Just past ssr VOR on V-431 at 16000 ft, zan cleared us for the lda DME runway 11 approach to sitka and advised us to switch to sitka radio. At this point we descended to 8000 ft, the MEA for that segment of the airway. At 34 DME off ssr we made the turn on the airway switching from #1 navigation to the #2 navigation, now en route to bka VOR via bka 327 degree radial. Established inbound to bka VOR we began a descent from 8000 ft to 5000 ft which is the MEA for that portion of V-431. Approximately 35-40 DME from bka at 5500 ft zan (through sitka radio) advised us we were left of course and to make an immediate 50 degree right turn and climb to 7000 ft and call zan. We complied with the instructions and flew to bka VOR and shot the same approach via 20 DME arc. Approaching bka we were given a heading to intercept the 295 degree radial north of bka. As we approached the 295 degree radial we asked the controller if they showed us joining the radial. Needle centered using the #2 navigation system. The controller said we hadn't reached the radial yet. Using #1 navigation system we made an uneventful landing. At all times during flight our aircraft instruments showed us to be on the airway. We thought we were receiving a good signal with the #2 navigation system, however, the course signal fluctuated a couple of times and the DME went off line a couple of times but only for a few seconds. Upon landing at sitka #2 DME was in error by 2 mi from airport to bka and from #1 navigation system. (#1 navigation showed correct) #2 navigation was written up as being in excessive error.

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Original NASA ASRS Text

Title: A DC9-30 FREIGHTER GETS A CALL FROM ZAN THROUGH SIT FSS THAT THEY ARE OFF COURSE ON THEIR DSCNT ON V-431 INTO SITKA.

Narrative: AIRLINE FLT WAS ENRTE FROM JUNEAU, AK, TO SITKA, AK. RTE OF FLT WAS JUNEAU TWO DEP, SISTERS ISLAND TRANSITION, SSR VOR V-431 TO CLUCK INTXN, LDA DME RWY 11 TO SITKA ARPT. JUST PAST SSR VOR ON V-431 AT 16000 FT, ZAN CLRED US FOR THE LDA DME RWY 11 APCH TO SITKA AND ADVISED US TO SWITCH TO SITKA RADIO. AT THIS POINT WE DSNDED TO 8000 FT, THE MEA FOR THAT SEGMENT OF THE AIRWAY. AT 34 DME OFF SSR WE MADE THE TURN ON THE AIRWAY SWITCHING FROM #1 NAV TO THE #2 NAV, NOW ENRTE TO BKA VOR VIA BKA 327 DEG RADIAL. ESTABLISHED INBOUND TO BKA VOR WE BEGAN A DSCNT FROM 8000 FT TO 5000 FT WHICH IS THE MEA FOR THAT PORTION OF V-431. APPROX 35-40 DME FROM BKA AT 5500 FT ZAN (THROUGH SITKA RADIO) ADVISED US WE WERE L OF COURSE AND TO MAKE AN IMMEDIATE 50 DEG R TURN AND CLB TO 7000 FT AND CALL ZAN. WE COMPLIED WITH THE INSTRUCTIONS AND FLEW TO BKA VOR AND SHOT THE SAME APCH VIA 20 DME ARC. APCHING BKA WE WERE GIVEN A HEADING TO INTERCEPT THE 295 DEG RADIAL N OF BKA. AS WE APCHED THE 295 DEG RADIAL WE ASKED THE CTLR IF THEY SHOWED US JOINING THE RADIAL. NEEDLE CTRED USING THE #2 NAV SYS. THE CTLR SAID WE HADN'T REACHED THE RADIAL YET. USING #1 NAV SYS WE MADE AN UNEVENTFUL LNDG. AT ALL TIMES DURING FLT OUR ACFT INSTS SHOWED US TO BE ON THE AIRWAY. WE THOUGHT WE WERE RECEIVING A GOOD SIGNAL WITH THE #2 NAV SYS, HOWEVER, THE COURSE SIGNAL FLUCTUATED A COUPLE OF TIMES AND THE DME WENT OFF LINE A COUPLE OF TIMES BUT ONLY FOR A FEW SECONDS. UPON LNDG AT SITKA #2 DME WAS IN ERROR BY 2 MI FROM ARPT TO BKA AND FROM #1 NAV SYS. (#1 NAV SHOWED CORRECT) #2 NAV WAS WRITTEN UP AS BEING IN EXCESSIVE ERROR.

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.