Narrative:

In syd the flight plan was checked against the ICAO flight plan message in dispatch. The plotting chart was prepared and no discrepancy was found. Company route syd/lax 15J was loaded, activated, and executed. Predeparture activities included a check of the initial route segments. Departure from sydney and the initial cruise were normal. Approaching pago the first officer found trask in place of tripp in the FMC. Tripp was in our flight plan as cleared by ATC, but not in the FMC data base. Tripp was also shown on our plotting chart but was not indicated on the (hi) 1 or (hi) 2 chart. We then received several calls from nandi radio. Nandi requested several VOR bearings and DME distances from our flight which required considerable time due to the need to work with HF radio relays. Communications were noisy and difficult. Apparently there was a flight inbound with a descent clearance through our altitude. We were given a clearance to track outbnd on the 071 radial of flight attendant which we were already past. We turned on our landing lights and he did the same. The flight next encountered WX and the tripp-trask discrepancy remained unresolved. Before crossing passa the relief crew came on duty and were briefed on the flight plan. I went off duty for my scheduled break. I had been off duty approximately 1 hour when the crew called for me to return to the cockpit. We then jointly identified the discrepancy and reported this to ATC. A new clearance was obtained and the remainder of the flight was as planned. Further discussion of the events leading up to the route problem highlighted the following points. Passa was the last waypoint on an organized track (B575). Tripp was the first waypoint on the random track portion of our planned route. At passa the relief crew gave hnl radio an estimate for trask as it was next in the FMC. ATC questioned the estimated position trask and suggested toram which added further confusion. Considerable time was spent looking for the 3 similar names: tripp, trask, toram. This further delayed recognition of the computer error. Callback conversation with reporter revealed the following: the flight department during the initial time period that a new navigation data base became effective. The route information on the bottom of the flight plan which is the information filed with ATC was correct but the waypoint information on the flight plan was not correct. This discrepancy was apparently not noticed by the flight crew. There is little doubt that both the regular flight crew and the relief flight crew were very confused by these events. Supplemental information from acn 136322: I was the relief crew and assumed pilot flying position after passing 'sapix'. The next position was 'passa' and thereafter 'trask' on the CDU and 'tripp' on the flight plan. The relieved crew mentioned that 'trask' was on track to 'tripp'. To make things more confusing, 'tripp' was not on the navigation chart, but was on the plotting chart, while 'trask' was on the navigation chart, but not on the plotting chart. After crossing 'passa' I was not convinced that 'trask' and 'tripp' were on the same course and asked the other relief pilot to plot a position, which confirmed my suspicion that we were south of course.

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Original NASA ASRS Text

Title: TRACK DEVIATION.

Narrative: IN SYD THE FLT PLAN WAS CHECKED AGAINST THE ICAO FLT PLAN MESSAGE IN DISPATCH. THE PLOTTING CHART WAS PREPARED AND NO DISCREPANCY WAS FOUND. COMPANY ROUTE SYD/LAX 15J WAS LOADED, ACTIVATED, AND EXECUTED. PREDEPARTURE ACTIVITIES INCLUDED A CHECK OF THE INITIAL ROUTE SEGMENTS. DEP FROM SYDNEY AND THE INITIAL CRUISE WERE NORMAL. APCHING PAGO THE F/O FOUND TRASK IN PLACE OF TRIPP IN THE FMC. TRIPP WAS IN OUR FLT PLAN AS CLRED BY ATC, BUT NOT IN THE FMC DATA BASE. TRIPP WAS ALSO SHOWN ON OUR PLOTTING CHART BUT WAS NOT INDICATED ON THE (HI) 1 OR (HI) 2 CHART. WE THEN RECEIVED SEVERAL CALLS FROM NANDI RADIO. NANDI REQUESTED SEVERAL VOR BEARINGS AND DME DISTANCES FROM OUR FLT WHICH REQUIRED CONSIDERABLE TIME DUE TO THE NEED TO WORK WITH HF RADIO RELAYS. COMS WERE NOISY AND DIFFICULT. APPARENTLY THERE WAS A FLT INBND WITH A DSCNT CLRNC THROUGH OUR ALT. WE WERE GIVEN A CLRNC TO TRACK OUTBND ON THE 071 RADIAL OF FA WHICH WE WERE ALREADY PAST. WE TURNED ON OUR LNDG LIGHTS AND HE DID THE SAME. THE FLT NEXT ENCOUNTERED WX AND THE TRIPP-TRASK DISCREPANCY REMAINED UNRESOLVED. BEFORE XING PASSA THE RELIEF CREW CAME ON DUTY AND WERE BRIEFED ON THE FLT PLAN. I WENT OFF DUTY FOR MY SCHEDULED BREAK. I HAD BEEN OFF DUTY APPROX 1 HR WHEN THE CREW CALLED FOR ME TO RETURN TO THE COCKPIT. WE THEN JOINTLY IDENTIFIED THE DISCREPANCY AND REPORTED THIS TO ATC. A NEW CLRNC WAS OBTAINED AND THE REMAINDER OF THE FLT WAS AS PLANNED. FURTHER DISCUSSION OF THE EVENTS LEADING UP TO THE ROUTE PROBLEM HIGHLIGHTED THE FOLLOWING POINTS. PASSA WAS THE LAST WAYPOINT ON AN ORGANIZED TRACK (B575). TRIPP WAS THE FIRST WAYPOINT ON THE RANDOM TRACK PORTION OF OUR PLANNED ROUTE. AT PASSA THE RELIEF CREW GAVE HNL RADIO AN ESTIMATE FOR TRASK AS IT WAS NEXT IN THE FMC. ATC QUESTIONED THE ESTIMATED POSITION TRASK AND SUGGESTED TORAM WHICH ADDED FURTHER CONFUSION. CONSIDERABLE TIME WAS SPENT LOOKING FOR THE 3 SIMILAR NAMES: TRIPP, TRASK, TORAM. THIS FURTHER DELAYED RECOGNITION OF THE COMPUTER ERROR. CALLBACK CONVERSATION WITH REPORTER REVEALED THE FOLLOWING: THE FLT DEPT DURING THE INITIAL TIME PERIOD THAT A NEW NAV DATA BASE BECAME EFFECTIVE. THE ROUTE INFO ON THE BOTTOM OF THE FLT PLAN WHICH IS THE INFO FILED WITH ATC WAS CORRECT BUT THE WAYPOINT INFO ON THE FLT PLAN WAS NOT CORRECT. THIS DISCREPANCY WAS APPARENTLY NOT NOTICED BY THE FLT CREW. THERE IS LITTLE DOUBT THAT BOTH THE REGULAR FLT CREW AND THE RELIEF FLT CREW WERE VERY CONFUSED BY THESE EVENTS. SUPPLEMENTAL INFORMATION FROM ACN 136322: I WAS THE RELIEF CREW AND ASSUMED PLT FLYING POSITION AFTER PASSING 'SAPIX'. THE NEXT POSITION WAS 'PASSA' AND THEREAFTER 'TRASK' ON THE CDU AND 'TRIPP' ON THE FLT PLAN. THE RELIEVED CREW MENTIONED THAT 'TRASK' WAS ON TRACK TO 'TRIPP'. TO MAKE THINGS MORE CONFUSING, 'TRIPP' WAS NOT ON THE NAV CHART, BUT WAS ON THE PLOTTING CHART, WHILE 'TRASK' WAS ON THE NAV CHART, BUT NOT ON THE PLOTTING CHART. AFTER XING 'PASSA' I WAS NOT CONVINCED THAT 'TRASK' AND 'TRIPP' WERE ON THE SAME COURSE AND ASKED THE OTHER RELIEF PLT TO PLOT A POSITION, WHICH CONFIRMED MY SUSPICION THAT WE WERE SOUTH OF COURSE.

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.