Narrative:

The flight was from rjcc (new chitose airport, sapporo, japan) to anc, ak, via A590 at FL330. Zan advised us we were in radar contact and that we were 65 mi south right of course. Upon plotting the INS position, we confirmed the off course position. We requested and received a vector to anc. We confirmed the waypoint coordinates stored in the INS were correct for A590 and then determined that the autoplt navigation mode selector was positioned to 'heading' rather than 'INS' as is normal when navigating by INS. The mode selector had been positioned to heading earlier when we crossed pinso intersection because the aircraft had commenced an undesired turn when the course required only a 1 degree change. The captain selected heading to stop the turn and steer back to the course (A590). Also, there were cloud buildups in the area that required some maneuvering to avoid. We determined the cause of the turn to be waypoints #1 through #7 had not been updated to the coordinates of the intxns ahead on A590. I entered and checked the waypoint coordinates in the INS for the remainder of the flight plan to anc. I then recorded and plotted an en route position check that indicated we were on course. I did not realize we were operating in heading mode and therefore we continued on the selected heading until advised of our position by zan. I believe the following factors contributed to this incident: 1) outdated navigation equipment -- this delco INS is only capable of 9 waypoints versus the entire flight plan for modern equipment. Poor annunciation of the selected autoplt navigation mode. 2) circadian rhythm disruptions -- 4 oddly spaced evening and early morning departures in 4 days and 4 time zones. 3) lack of radar coverage -- a radar site at shemya would vastly improve safety on the north pacific rtes and in this case would have detected the error before becoming significant.

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Original NASA ASRS Text

Title: B747 FLC OFF TRACK ENRTE FROM CST TO ANC.

Narrative: THE FLT WAS FROM RJCC (NEW CHITOSE ARPT, SAPPORO, JAPAN) TO ANC, AK, VIA A590 AT FL330. ZAN ADVISED US WE WERE IN RADAR CONTACT AND THAT WE WERE 65 MI S R OF COURSE. UPON PLOTTING THE INS POS, WE CONFIRMED THE OFF COURSE POS. WE REQUESTED AND RECEIVED A VECTOR TO ANC. WE CONFIRMED THE WAYPOINT COORDINATES STORED IN THE INS WERE CORRECT FOR A590 AND THEN DETERMINED THAT THE AUTOPLT NAV MODE SELECTOR WAS POSITIONED TO 'HDG' RATHER THAN 'INS' AS IS NORMAL WHEN NAVING BY INS. THE MODE SELECTOR HAD BEEN POSITIONED TO HDG EARLIER WHEN WE CROSSED PINSO INTXN BECAUSE THE ACFT HAD COMMENCED AN UNDESIRED TURN WHEN THE COURSE REQUIRED ONLY A 1 DEG CHANGE. THE CAPT SELECTED HDG TO STOP THE TURN AND STEER BACK TO THE COURSE (A590). ALSO, THERE WERE CLOUD BUILDUPS IN THE AREA THAT REQUIRED SOME MANEUVERING TO AVOID. WE DETERMINED THE CAUSE OF THE TURN TO BE WAYPOINTS #1 THROUGH #7 HAD NOT BEEN UPDATED TO THE COORDINATES OF THE INTXNS AHEAD ON A590. I ENTERED AND CHKED THE WAYPOINT COORDINATES IN THE INS FOR THE REMAINDER OF THE FLT PLAN TO ANC. I THEN RECORDED AND PLOTTED AN ENRTE POS CHK THAT INDICATED WE WERE ON COURSE. I DID NOT REALIZE WE WERE OPERATING IN HDG MODE AND THEREFORE WE CONTINUED ON THE SELECTED HDG UNTIL ADVISED OF OUR POS BY ZAN. I BELIEVE THE FOLLOWING FACTORS CONTRIBUTED TO THIS INCIDENT: 1) OUTDATED NAV EQUIPMENT -- THIS DELCO INS IS ONLY CAPABLE OF 9 WAYPOINTS VERSUS THE ENTIRE FLT PLAN FOR MODERN EQUIP. POOR ANNUNCIATION OF THE SELECTED AUTOPLT NAV MODE. 2) CIRCADIAN RHYTHM DISRUPTIONS -- 4 ODDLY SPACED EVENING AND EARLY MORNING DEPS IN 4 DAYS AND 4 TIME ZONES. 3) LACK OF RADAR COVERAGE -- A RADAR SITE AT SHEMYA WOULD VASTLY IMPROVE SAFETY ON THE NORTH PACIFIC RTES AND IN THIS CASE WOULD HAVE DETECTED THE ERROR BEFORE BECOMING SIGNIFICANT.

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.