Widebody transport departing for oceanic flight has FMC equipment problem. Divert land.

Attributes
ACN	229100
Time
Date	199212
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : tpe
State Reference	FO
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Widebody, Low Wing, 4 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	climbout : intermediate altitude cruise other other
Route In Use	enroute : pacific enroute : other oceanic enroute airway : tpe
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time total : 19334 flight time type : 227
ASRS Report	229100
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : declared emergency none taken : unable other
Consequence	Other
Supplementary
Primary Problem	Aircraft

Narrative:

Flight was scheduled from tpe to sfo. Shortly after takeoff it became apparent that there was a problem with the navigation system. The magenta line on the nd's was not visible and a check of our position on the FMC showed a west indication. Since the WX was good in the tokyo area, I made the decision to proceed to nrt. Dispatch and maintenance were contacted and the nrt diversion coordinated. Approximately 108000 pounds of fuel was dumped and we landed at nrt 2:59 hours after departing tpe. At tpe during the cockpit setup I inserted the ramp position in the FMC and checked it with the coordinates displayed on the large sign by the gate number. While at the gate the right FMC failed and a mechanic was called. After resetting some circuit breakers the FMC returned to normal. As I recall at this point everything was normal. After takeoff from tpe there was an intermittent failure of the left FMC 9 mins after departing tpe. This was indicated by a review of the fault history message report in nrt.

Original NASA ASRS Text

Title: WDB DEPARTING FOR OCEANIC FLT HAS FMC EQUIP PROB. DIVERT LAND.

Narrative: FLT WAS SCHEDULED FROM TPE TO SFO. SHORTLY AFTER TKOF IT BECAME APPARENT THAT THERE WAS A PROB WITH THE NAV SYS. THE MAGENTA LINE ON THE ND'S WAS NOT VISIBLE AND A CHK OF OUR POS ON THE FMC SHOWED A W INDICATION. SINCE THE WX WAS GOOD IN THE TOKYO AREA, I MADE THE DECISION TO PROCEED TO NRT. DISPATCH AND MAINT WERE CONTACTED AND THE NRT DIVERSION COORDINATED. APPROX 108000 LBS OF FUEL WAS DUMPED AND WE LANDED AT NRT 2:59 HRS AFTER DEPARTING TPE. AT TPE DURING THE COCKPIT SETUP I INSERTED THE RAMP POS IN THE FMC AND CHKED IT WITH THE COORDINATES DISPLAYED ON THE LARGE SIGN BY THE GATE NUMBER. WHILE AT THE GATE THE R FMC FAILED AND A MECH WAS CALLED. AFTER RESETTING SOME CIRCUIT BREAKERS THE FMC RETURNED TO NORMAL. AS I RECALL AT THIS POINT EVERYTHING WAS NORMAL. AFTER TKOF FROM TPE THERE WAS AN INTERMITTENT FAILURE OF THE L FMC 9 MINS AFTER DEPARTING TPE. THIS WAS INDICATED BY A REVIEW OF THE FAULT HISTORY MESSAGE RPT IN NRT.

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.