Narrative:

Initially cleared lgw to den via nat track a, which read 58/10 60/20 61/30 61/40 59/50 prawn ydp. The track was loaded into the 3 INS on preflight and checked for accuracy. Approximately 3 mins before entering the track system at 59N-10W, we were given a rerte that read 59/10 61/20 62/40 60/50 58/60 (later changed by oceanic control to 59/60) lakes, and cleared direct to the first fix (59/10). I quickly entered the first fix in the #2 INS so we could go direct as cleared, and then continued to enter the remaining latitude/longs of the rerte. The captain loaded the route into the #1 and #3 INS's. At the third waypoint (62/30), a xchk of the INS's showed crosstrack errors of 29 and 28 mi. #2 INS was navigating and of course showed no xtrack error. Because of the exceptionally large difference between #'south 1 and 3, and #2, we started a turn toward where the #1 and #3 INS's showed we should be (suspected that #2 was in error). On inspection of the waypoint inputs, it showed that the 62/30 waypoint was entered into #2 INS by me as 62/30 north 30/00 west instead of the correct 62/00 north 30/00 west. Time was critical at the point of rerte to input the first fix of that rerte, so we could go direct as cleared. I hurriedly input the first fix, but just as fast put in the remaining fixes into the #2 (navigating) INS. I didn't need to do it so fast. In hindsight, it was this hurried way of doing it that led to the keystroke mistake on the third waypoint down the line (62/30). After loading the rerte, I should have rechked the inputs for accuracy--I didn't.

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Original NASA ASRS Text

Title: PROGRAMMED INS IN ERROR WHEN REROUTED.

Narrative: INITIALLY CLRED LGW TO DEN VIA NAT TRACK A, WHICH READ 58/10 60/20 61/30 61/40 59/50 PRAWN YDP. THE TRACK WAS LOADED INTO THE 3 INS ON PREFLT AND CHKED FOR ACCURACY. APPROX 3 MINS BEFORE ENTERING THE TRACK SYS AT 59N-10W, WE WERE GIVEN A RERTE THAT READ 59/10 61/20 62/40 60/50 58/60 (LATER CHANGED BY OCEANIC CTL TO 59/60) LAKES, AND CLRED DIRECT TO THE FIRST FIX (59/10). I QUICKLY ENTERED THE FIRST FIX IN THE #2 INS SO WE COULD GO DIRECT AS CLRED, AND THEN CONTINUED TO ENTER THE REMAINING LAT/LONGS OF THE RERTE. THE CAPT LOADED THE ROUTE INTO THE #1 AND #3 INS'S. AT THE THIRD WAYPOINT (62/30), A XCHK OF THE INS'S SHOWED CROSSTRACK ERRORS OF 29 AND 28 MI. #2 INS WAS NAVIGATING AND OF COURSE SHOWED NO XTRACK ERROR. BECAUSE OF THE EXCEPTIONALLY LARGE DIFFERENCE BTWN #'S 1 AND 3, AND #2, WE STARTED A TURN TOWARD WHERE THE #1 AND #3 INS'S SHOWED WE SHOULD BE (SUSPECTED THAT #2 WAS IN ERROR). ON INSPECTION OF THE WAYPOINT INPUTS, IT SHOWED THAT THE 62/30 WAYPOINT WAS ENTERED INTO #2 INS BY ME AS 62/30 N 30/00 W INSTEAD OF THE CORRECT 62/00 N 30/00 W. TIME WAS CRITICAL AT THE POINT OF RERTE TO INPUT THE FIRST FIX OF THAT RERTE, SO WE COULD GO DIRECT AS CLRED. I HURRIEDLY INPUT THE FIRST FIX, BUT JUST AS FAST PUT IN THE REMAINING FIXES INTO THE #2 (NAVIGATING) INS. I DIDN'T NEED TO DO IT SO FAST. IN HINDSIGHT, IT WAS THIS HURRIED WAY OF DOING IT THAT LED TO THE KEYSTROKE MISTAKE ON THE THIRD WAYPOINT DOWN THE LINE (62/30). AFTER LOADING THE RERTE, I SHOULD HAVE RECHKED THE INPUTS FOR ACCURACY--I DIDN'T.

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.