NAV DEV OF 120 MI OVER THE ATLANTIC.

Narrative

ACFT OPERATED BTWN GANDER; NFLD; AND MANCHESTER; UK. RTE CLRNC: 50N/50W; 52N/40W; 53N/30W; 52N/20W; 52N/15W; DOLIP. PIC (PF) ENTERED RTE INTO #1 NAV (GPS) AND SIC (PNF) ENTERED RTE INTO #2 NAV (ONS) IN ACCORDANCE WITH OPERATOR POLICY. PRE-DEP GND CHKS REVEALED NO APPARENT ERRORS IN NAV DATA FOR FLT. RTE CONFIRMED BY GANDER ATC - - FLT DEPARTED AT XA00Z. ENRTE OP AND NAV WERE ROUTINE -- POS CONFIRMED BY PLOTTING IN ACCORDANCE WITH ACCEPTED PROCS. A PLOT MADE APPROX 10 MINS AFTER PASSING 52N/20W INDICATED THAT THE ACFT POS WAS ABOUT N5126 RATHER THAN N5200.0. THIS S DEV DID NOT REGISTER AS BEING ERRONEOUS. APCHING 15W SHANNON RADAR INFORMED FLT THAT IT WAS APCHING 50N/15W RATHER THAN 52N/15W. WE HAD BEEN NON- RADAR WITH SHANWICK OCEANIC TILL THIS POINT. COINCIDENTALLY AS FLT APCHED 15W; PNF HAD BRIEF COM FAILURE. EXECUTED CORRECTING TURN AS DIRECTED BY SHANNON. BAL UNEVENTFUL FLT LANDED AT XD00Z. ON GND INVESTIGATION REVEALED THAT WAYPOINT WHICH HAD BEEN 'TAGGED' BY GPS AS 5215 (52N/15W) HAD BEEN DEFINED AS 50N/15W. THIS ERROR RESULTED IN ABOVE DEV. SUPPLEMENTAL INFO FROM ACN 316107: I LOADED THE ROUTE INTO THE GPS. I WAS NOT RUSHED; AND WAS VERY METHODICAL IN LOADING THE WAYPOINTS. MOST OF THE WAYPOINTS WERE USER WAYPOINTS DEFINED BY LATITUDE AND LONGITUDE COORDINATES. FIRST AN IDENTIFIER IS CREATED SUCH AS '5050.' THEN N50.00.00 W50.00.00 IS ENTERED. THE ENTER KEY PUSHED AND IF IT IS DISPLAYED CORRECTLY; THE ENTER KEY IS PUSHED AGAIN TO COMPLETE THE ENTRY. IF THIS WAYPOINT IDENTIFIER HAS BEEN USED ON A PREVIOUS FLT; THE COORDINATES PREVIOUSLY USED WILL BE DISPLAYED AND IF CORRECT THE ENTER KEY PUSHED TO COMPLETE THE ENTRY. ON PREVIOUS FLTS; I HAVE FOUND WAYPOINTS WITH INCORRECT COORDINATES WHILE LOADING THE GPS. SO I WAS VERY CAREFUL THAT THIS DIDN'T HAPPEN. I CANNOT SAY IF 5215 REQUIRED AN INITIAL ENTRY; BUT I AM POSITIVE THAT IT WAS CORRECTLY DISPLAYED AS N52.00.00 W15.00.00. IN REVIEWING THE 10 MINUTE PLOT IT WAS R OF COURSE BY APPROX ONE DEG; BUT IT WAS PLOTTED ON THE CHART AS BEING ON COURSE. THE COPLT'S HSI COURSE INDICATOR WITH OMEGA SELECTED WILL DIFFER FROM WHAT IT IS. IN THE FUTURE; THE OMEGA UNIT WILL DISPLAY CROSSTRACK MOST OF THE TIME. FATIGUE MAY HAVE BEEN A FACTOR AS WE HAD BEEN ON DUTY FOR 13 HRS 35 MINS AND I HAD BEEN AWAKE AN ADDITIONAL 6 HRS. SUPPLEMENTAL INFO FROM ACN 316450: THE GPS COUPLED TO THE AUTOPLT WORKED AS ADVERTISED UNTIL 52/20; AND AFTER 50/15; WHICH LEAVES US TO PROGRAMMING. HOW THE POS 50/15 WAS ENTERED COULD ONLY BE SPECULATED AS FINGER TROUBLE; WHICH WENT UNDETECTED UNTIL REACHING THAT POS. THERE WERE SOME CUES WHICH SHOULD HAVE ALERTED US TO THE IMPENDING ERROR; HOWEVER; THESE CUES WERE NOT HEEDED. FOR EXAMPLE: THERE WAS AN ACFT ABOVE US ON THE SAME TRACK WHICH WE FOLLOWED ACROSS; THAT ACFT TURNED TO THE L; WE TURNED TO THE R. THIS FLT WAS PLANNED WITHIN THE CURRENT REGS; AND ALTHOUGH FATIGUE IS NO EXCUSE; IT IS A SERIOUS CONSIDERATION AS A CONTRIBUTING FACTOR WHICH NEW REGS OUGHT TO ADDRESS. THE CURRENT REGS ALLOW NON-SCHEDULED CARRIERS TO SCHEDULE THEIR PLTS FOR DUTY FOR UP TO 30 HRS. I'VE BEEN MORE THAN ONCE SO SCHEDULED. I WAS QUIETLY WARNED; THAT REFUSAL TO WORK AS ASSIGNED; WILL END IN TERMINATION. WITH SO MANY AIRLINE PLTS UNEMPLOYED; 'I NEED TO KEEP MY JOB.'