Narrative:

Copilot loaded his INS for a random route guam to hnl and x-filed information to other 2 units. I checked coordinates off my INS against ICAO flight plan and missed the only incorrect position loaded. Company flight plan had us routed north to pick up jet stream. Flight planned route: gum, sando, W21 snapp, 17N 150E, 20N 155E, 22N 160 east, 25N 170 east, 25N 180 east, 24N 170 west, pnzh, canon, booke 7 hnl. The misprogrammed coordinate and the one I did not catch was the latitude at 170W. The copilot put in 25N 170W instead of 24N 170W. Shortly after takeoff, guam center cleared us direct to 17N 1505 flight planned route. The flight progressed normally, even though my position report at 25N 170E gave an estimate for 25N 180E and my next position to be 15N 170W. 10 mins after giving my 25N 180E position report, ZOA queried us to confirm our latitude for 170W. I told them it was 25N. ZOA then gave us clearance to hnl from present position direct to 25N 170W, canon, booke 7 hnl, block altitude FL350/370. I acknowledged clearance, rechked ICAO flight plan and discovered we should have been going to 24N 170W. In the time it took ZOA to call us back with the revised clearance, I estimate we were approximately 25 NM north of our original flight planned route. Even though I missed catching the error on my INS check out of guam, I did plot the course correctly on our plotting chart. When I plotted our position at 179W and it was showing us still up at 25N, I checked the INS again and assumed I misplotted. About this time ZOA was calling us and giving us the new clearance. This time of yr, the company's computer flight plans almost always send us farther north of our east rtes to take advantage of the increased tailwinds. I must have been thinking, 'stay north as long as possible before angling southeast to hnl.' why do people sometimes misread #south? I don't know why I did in this case, but I did. I appreciate ZOA giving us the clearance to conform with my screw-up.

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Original NASA ASRS Text

Title: ACR WDB TRACK HEADING DEVIATION ON EXTENDED OVERWATER OPERATION AT GUAM TO HNL.

Narrative: COPLT LOADED HIS INS FOR A RANDOM RTE GUAM TO HNL AND X-FILED INFO TO OTHER 2 UNITS. I CHKED COORDINATES OFF MY INS AGAINST ICAO FLT PLAN AND MISSED THE ONLY INCORRECT POS LOADED. COMPANY FLT PLAN HAD US ROUTED N TO PICK UP JET STREAM. FLT PLANNED RTE: GUM, SANDO, W21 SNAPP, 17N 150E, 20N 155E, 22N 160 E, 25N 170 E, 25N 180 E, 24N 170 W, PNZH, CANON, BOOKE 7 HNL. THE MISPROGRAMMED COORDINATE AND THE ONE I DID NOT CATCH WAS THE LATITUDE AT 170W. THE COPLT PUT IN 25N 170W INSTEAD OF 24N 170W. SHORTLY AFTER TKOF, GUAM CENTER CLRED US DIRECT TO 17N 1505 FLT PLANNED RTE. THE FLT PROGRESSED NORMALLY, EVEN THOUGH MY POS RPT AT 25N 170E GAVE AN ESTIMATE FOR 25N 180E AND MY NEXT POS TO BE 15N 170W. 10 MINS AFTER GIVING MY 25N 180E POS RPT, ZOA QUERIED US TO CONFIRM OUR LATITUDE FOR 170W. I TOLD THEM IT WAS 25N. ZOA THEN GAVE US CLRNC TO HNL FROM PRESENT POS DIRECT TO 25N 170W, CANON, BOOKE 7 HNL, BLOCK ALT FL350/370. I ACKNOWLEDGED CLRNC, RECHKED ICAO FLT PLAN AND DISCOVERED WE SHOULD HAVE BEEN GOING TO 24N 170W. IN THE TIME IT TOOK ZOA TO CALL US BACK WITH THE REVISED CLRNC, I ESTIMATE WE WERE APPROX 25 NM N OF OUR ORIGINAL FLT PLANNED RTE. EVEN THOUGH I MISSED CATCHING THE ERROR ON MY INS CHK OUT OF GUAM, I DID PLOT THE COURSE CORRECTLY ON OUR PLOTTING CHART. WHEN I PLOTTED OUR POS AT 179W AND IT WAS SHOWING US STILL UP AT 25N, I CHKED THE INS AGAIN AND ASSUMED I MISPLOTTED. ABOUT THIS TIME ZOA WAS CALLING US AND GIVING US THE NEW CLRNC. THIS TIME OF YR, THE COMPANY'S COMPUTER FLT PLANS ALMOST ALWAYS SEND US FARTHER N OF OUR E RTES TO TAKE ADVANTAGE OF THE INCREASED TAILWINDS. I MUST HAVE BEEN THINKING, 'STAY N AS LONG AS POSSIBLE BEFORE ANGLING SE TO HNL.' WHY DO PEOPLE SOMETIMES MISREAD #S? I DON'T KNOW WHY I DID IN THIS CASE, BUT I DID. I APPRECIATE ZOA GIVING US THE CLRNC TO CONFORM WITH MY SCREW-UP.

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.