C750 CREW EXPERIENCES GROSS NAV ERROR IN CZQX AIRSPACE AFTER ENTERING WRONG LATITUDE INTO FMS.

Narrative

WE WERE CLRED FROM LONDON; UNITED KINGDOM; TO GANDER VIA GIPER UN516BTO 50N015W; 51N020W; 51N030W; 51N040W; 50N050W; YQX. OUR REQUESTED AND CLRED ROUTING WERE THE SAME. THE RTE WAS A RANDOM RTE OVER THE TOP OF THE TRACKS; STARTING AT FL430. THE ACFT WAS A C750 (COMMONLY REFERRED TO AS A CITATION X) EQUIPPED WITH A DUAL FMS; DUAL IRS AND DUAL GPS. THE CREW AND ACFT WERE MNPS AND RVSM QUALIFIED. BOTH PLTS HAVE COMPLETED NUMEROUS OCEANIC XINGS. I WAS THE PIC AND WAS IN THE R SEAT. BOTH PLTS WERE 'TYPE RATED' CAPTS FOR OUR COMPANY. WHILE WE WERE WAITING FOR OUR PAX; I LOADED THE FMS WITH THE EXPECTED OCEANIC RTE AND I COMPLETED A PLOTTING CHART FOR OUR RTE AS IT WAS FILED. THE FLT PROGRESSED 'NORMALLY' UNTIL WE CHKED IN WITH GANDER CTR AT 50W. THEY ADVISED US THAT WE WERE AT 51N VICE OUR EXPECTED 50N AND THAT WE WERE BEING ASSESSED A 'GROSS NAV ERROR' FOR BEING MORE THAN 50 NM OFF COURSE (WE WERE 1 DEG/60 NM OFF COURSE AT THAT TIME). BECAUSE WE WERE AT FL470 PRIOR TO 40W; WE WERE ABOVE MNPS AIRSPACE AT THE TIME WE WERE OFF RTE. GANDER ALSO INFORMED US THAT THERE WAS NO 'LOSS OF SEPARATION' BECAUSE THERE WAS NO TFC IN THAT AREA AT THAT LATITUDE/ALT. THE PROB AROSE BECAUSE I INSERTED THE WRONG LATITUDE (51N VICE 50N) INTO THE FMS. THE PROB WAS COMPOUNDED BECAUSE I FAILED TO XCHK MY WORK AND BECAUSE THE OTHER PLT DID NOT INDEPENDENTLY DOUBLECHK MY ENTRIES IN ACCORDANCE WITH COMPANY POLICY. THE PLOTTING CHART WAS FILLED OUT CORRECTLY. NORMALLY THIS WOULD HAVE GIVEN ME A LAST CHANCE TO CATCH MY ERROR BY NOTING THE ACFT DRIFTING N OF THE PLOTTED COURSE LINE SEVERAL MINS AFTER WAYPOINT (40W) PASSAGE. I HAD BEEN PLOTTING POINTS BTWN WAYPOINTS THROUGHOUT THE FLT. I HAD WAITED UNTIL GIVING MY 40W POS RPT TO EAT LUNCH. AFTER GIVING THE RPT; I STARTED TO EAT AND IN THE PROCESS; NEGLECTED TO PLOT A POS 1-2 DEGS BEYOND 40W THAT WOULD HAVE PROVIDED MY LAST CLUE AS TO BEING OFF COURSE. A LAST NOTE: USUALLY I READ MY POS RPT FROM THE FMS AFTER WRITING IT ON THE COMPUTER FLT PLAN. THIS TIME I READ THE POS RPT OFF THE FLT PLAN THAT INCLUDED THE CORRECT WAYPOINT (50N). HAD I FOLLOWED MY USUAL PROC; I WOULD HAVE READ THE RPT FROM THE FMS AND INCLUDED MY WRONG WAYPOINT WHICH WOULD HAVE ALERTED GANDER OCEANIC THAT THERE WAS A PROB WITH MY ROUTING. THIS WOULD HAVE PERMITTED THEM TO COME BACK WITH A CORRECTION THAT WOULD HAVE RESOLVED THE PROB. RESULTING CORRECTIVE ACTION: BOTH OF US WILL; AT AN UPCOMING PLT MEETING; DISCUSS THE ENTIRE EVENT WITH ALL THE OTHER COMPANY PLTS IN AN EFFORT TO INSTILL IN THEM THE NEED TO BE CONSTANTLY VIGILANT AGAINST COMPLACENCY; WHICH WAS AN OVERRIDING FACTOR IN THIS INCIDENT. WE WILL ALSO; WITHIN THE NEXT 30 DAYS; COMPLETE AN INTL PROCS REFRESHER COURSE.