Narrative:

On an NDB-a approach to the cordova airport, ak. Dual FMC aircraft flying LNAV with both hitchenbrook and glacier river NDB's tuned and idented. On final approach both HSI's lost map display and LNAV capability. Continued with raw data. Broke out of IMC at 1200 ft MSL. Maintained 1000 ft MSL initially then descended to 600 ft MSL (MDA) 40 KTS of wind from 2 O'clock position. Visibility 5 mi. Slightly disoriented due to loss of FMC's depiction and snow covered ground. Executed missed approach on timing, began climbing right turn to 2500 ft. Captain initially turned 270 degrees and was initially confused with the split NDB needles. Mistook hitchenbrook for glacier river. I told the captain to turn left 45 degrees to intercept course, with the 40 KTS of wind on our tail now we blew through the course, with terrain to the west, we received a terrain caution. At that time we immediately went to maximum power and began a climbing left turn. At this point I contacted juneau radio and informed them we executed the missed and were climbing to 5000 ft. Radio told us to contact zan. By this time the captain and I were confident terrain was clear and he told me to request a clearance to hitchenbrook at 6000 ft, and plan on the ILS runway 22 to cdv. Upon contact with zan, we confirmed our altitude and position and received clearance to glacier river for the ILS runway 27. After this, we completed an uneventful ILS procedure turn and landing at cordova. On final analysis the captain and I both realized in the back of our minds we were still wondering why we lost the FMC's displays. Also, we realized we should have discussed the split needle presentation and a good initial rollout missed approach heading. We both learned a lot. As far as a safety issue, I believe our priorities as far as terrain avoidance were very good and initially climbing versus discussing it first was well ingrained in both of us.

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Original NASA ASRS Text

Title: ACFT LOST BOTH FMC'S DURING A NON PRECISION APCH AND CONTINUED THE APCH USING RAW DATA. AT MINIMUMS THE FLC WAS UNABLE TO LOCATE THE ARPT DUE TO STRONG WINDS AND BEGAN A MISSED APCH. DURING THE MISSED APCH THE FLC RECEIVED A TERRAIN WARNING FROM THE GPWS AND CLBED TO A SAFE ALT. ARTCC INFORMED FLC THEY DID NOT HAVE A CLRNC TO MAINTAIN 6000 FT MSL.

Narrative: ON AN NDB-A APCH TO THE CORDOVA ARPT, AK. DUAL FMC ACFT FLYING LNAV WITH BOTH HITCHENBROOK AND GLACIER RIVER NDB'S TUNED AND IDENTED. ON FINAL APCH BOTH HSI'S LOST MAP DISPLAY AND LNAV CAPABILITY. CONTINUED WITH RAW DATA. BROKE OUT OF IMC AT 1200 FT MSL. MAINTAINED 1000 FT MSL INITIALLY THEN DSNDED TO 600 FT MSL (MDA) 40 KTS OF WIND FROM 2 O'CLOCK POS. VISIBILITY 5 MI. SLIGHTLY DISORIENTED DUE TO LOSS OF FMC'S DEPICTION AND SNOW COVERED GND. EXECUTED MISSED APCH ON TIMING, BEGAN CLBING R TURN TO 2500 FT. CAPT INITIALLY TURNED 270 DEGS AND WAS INITIALLY CONFUSED WITH THE SPLIT NDB NEEDLES. MISTOOK HITCHENBROOK FOR GLACIER RIVER. I TOLD THE CAPT TO TURN L 45 DEGS TO INTERCEPT COURSE, WITH THE 40 KTS OF WIND ON OUR TAIL NOW WE BLEW THROUGH THE COURSE, WITH TERRAIN TO THE W, WE RECEIVED A TERRAIN CAUTION. AT THAT TIME WE IMMEDIATELY WENT TO MAX PWR AND BEGAN A CLBING L TURN. AT THIS POINT I CONTACTED JUNEAU RADIO AND INFORMED THEM WE EXECUTED THE MISSED AND WERE CLBING TO 5000 FT. RADIO TOLD US TO CONTACT ZAN. BY THIS TIME THE CAPT AND I WERE CONFIDENT TERRAIN WAS CLR AND HE TOLD ME TO REQUEST A CLRNC TO HITCHENBROOK AT 6000 FT, AND PLAN ON THE ILS RWY 22 TO CDV. UPON CONTACT WITH ZAN, WE CONFIRMED OUR ALT AND POS AND RECEIVED CLRNC TO GLACIER RIVER FOR THE ILS RWY 27. AFTER THIS, WE COMPLETED AN UNEVENTFUL ILS PROC TURN AND LNDG AT CORDOVA. ON FINAL ANALYSIS THE CAPT AND I BOTH REALIZED IN THE BACK OF OUR MINDS WE WERE STILL WONDERING WHY WE LOST THE FMC'S DISPLAYS. ALSO, WE REALIZED WE SHOULD HAVE DISCUSSED THE SPLIT NEEDLE PRESENTATION AND A GOOD INITIAL ROLLOUT MISSED APCH HDG. WE BOTH LEARNED A LOT. AS FAR AS A SAFETY ISSUE, I BELIEVE OUR PRIORITIES AS FAR AS TERRAIN AVOIDANCE WERE VERY GOOD AND INITIALLY CLBING VERSUS DISCUSSING IT FIRST WAS WELL INGRAINED IN BOTH OF US.

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.