Narrative:

We reported over the fix lumbr (58N/70W) with an estimate for cyril 50 460N/80W, 557 NM) of 40 mins after passing lumbr. Cymx questioned our estimate. We checked our computer flight plan which we had used to program our INS and ONS units and it showed cyril as 56 460N--thus the error. Our computer flight plan showed 333 NM lumbr to cyril and not the correct arwy (NA364), since we were heading for 56N instead of 50N. This required reprogramming both INS units and the ONS unit with the proper coordinate. If cymx had not questioned the estimate we certainly would have infringed on another arwy/route. It is the airline procedure to check computer coordinate against chart coordinates, but something broke the chain of our normal procedures today and allowed the error to go unnoticed. There is no radar coverage in the area and the heading we had programmed would have taken us across several arwys/routes (also west/O radar coverage). A double check of chart verses computer positions is a must. Some human programmed the error and we humans did not follow complete procedures and so it got by us.

Google
 

Original NASA ASRS Text

Title: ACR WDB DEVIATED FROM CLRNC ROUTE IN NORTHERN CANADA.

Narrative: WE RPTED OVER THE FIX LUMBR (58N/70W) WITH AN ESTIMATE FOR CYRIL 50 460N/80W, 557 NM) OF 40 MINS AFTER PASSING LUMBR. CYMX QUESTIONED OUR ESTIMATE. WE CHKED OUR COMPUTER FLT PLAN WHICH WE HAD USED TO PROGRAM OUR INS AND ONS UNITS AND IT SHOWED CYRIL AS 56 460N--THUS THE ERROR. OUR COMPUTER FLT PLAN SHOWED 333 NM LUMBR TO CYRIL AND NOT THE CORRECT ARWY (NA364), SINCE WE WERE HDG FOR 56N INSTEAD OF 50N. THIS REQUIRED REPROGRAMMING BOTH INS UNITS AND THE ONS UNIT WITH THE PROPER COORDINATE. IF CYMX HAD NOT QUESTIONED THE ESTIMATE WE CERTAINLY WOULD HAVE INFRINGED ON ANOTHER ARWY/ROUTE. IT IS THE AIRLINE PROC TO CHK COMPUTER COORDINATE AGAINST CHART COORDINATES, BUT SOMETHING BROKE THE CHAIN OF OUR NORMAL PROCS TODAY AND ALLOWED THE ERROR TO GO UNNOTICED. THERE IS NO RADAR COVERAGE IN THE AREA AND THE HDG WE HAD PROGRAMMED WOULD HAVE TAKEN US ACROSS SEVERAL ARWYS/ROUTES (ALSO W/O RADAR COVERAGE). A DOUBLE CHK OF CHART VERSES COMPUTER POSITIONS IS A MUST. SOME HUMAN PROGRAMMED THE ERROR AND WE HUMANS DID NOT FOLLOW COMPLETE PROCS AND SO IT GOT BY US.

Data retrieved from NASA's ASRS site as of August 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.