Narrative:

Oceanic clearance (shanwick) changed our route while airborne from 59N 10 west direct 60N 20 west direct 61N 30W as filed and originally cleared to 60N 10W direct 61N 20W direct 61N 30W. The captain only had received and copied the clearance onto the flight plan and inserted the changes into all 3 INS remotely (from #1). The first officer checked the accuracy of the waypoints on #2. I (second officer) checked the distance between waypoints to ensure accuracy (I had to recalculate distances because they weren't on the flight plan). Also I think I did check the waypoint latitude/longitude. We passed over 60N 10W and reported. I did the fuel/INS accuracy check, as called for in our procedures. We reported passing 61N 20W ETA XX12Z/air traffic area XX17Z. I did the fuel/INS accuracy check and everything looked ok. At approximately XX30 Z the captain said, 'oh shit' (first sign of trouble). He had just done a fix (required approximately 10 mins after the previous fix by our SOP). We showed ourselves 15-20 mi south of course. We initiated a 45 degree right turn, 320 degrees true (approximately position 60 44N 2416W). We were back on course at 61 04.8N 25W at XX41Z. As we looked at our mistake we had in fact gone from 60N 10W to 60N 20W, instead of 61N 20W, then to 61N 30W. We looked at the waypoint in the INS. It had been incorrectly inserted by the captain, even though he had written the dew clearance correctly on the flight plan. Neither the first officer nor I caught the error of 1 digit. Furthermore, the fix 10 mins after the turn at 60N 10W didn't reveal a discrepancy large enough to notice. The track check was within a few degrees. The INS check at what I thought was 61N 20W showed us at 60N 20W. I just missed it, lacking concentration perhaps due to fatigue (only slept 2 hours that night). We did not report it to oceanic because we were back on course within a few mins. On one brought it to our attention. The big question: how could we have screwed up?? The procedures are good, but we failed to pay attention to details.

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Original NASA ASRS Text

Title: HEADING TRACK POS DEVIATION.

Narrative: OCEANIC CLRNC (SHANWICK) CHANGED OUR RTE WHILE AIRBORNE FROM 59N 10 W DIRECT 60N 20 W DIRECT 61N 30W AS FILED AND ORIGINALLY CLRED TO 60N 10W DIRECT 61N 20W DIRECT 61N 30W. THE CAPT ONLY HAD RECEIVED AND COPIED THE CLRNC ONTO THE FLT PLAN AND INSERTED THE CHANGES INTO ALL 3 INS REMOTELY (FROM #1). THE F/O CHKED THE ACCURACY OF THE WAYPOINTS ON #2. I (S/O) CHKED THE DISTANCE BTWN WAYPOINTS TO ENSURE ACCURACY (I HAD TO RECALCULATE DISTANCES BECAUSE THEY WEREN'T ON THE FLT PLAN). ALSO I THINK I DID CHK THE WAYPOINT LAT/LONGITUDE. WE PASSED OVER 60N 10W AND RPTED. I DID THE FUEL/INS ACCURACY CHK, AS CALLED FOR IN OUR PROCS. WE RPTED PASSING 61N 20W ETA XX12Z/ATA XX17Z. I DID THE FUEL/INS ACCURACY CHK AND EVERYTHING LOOKED OK. AT APPROX XX30 Z THE CAPT SAID, 'OH SHIT' (FIRST SIGN OF TROUBLE). HE HAD JUST DONE A FIX (REQUIRED APPROX 10 MINS AFTER THE PREVIOUS FIX BY OUR SOP). WE SHOWED OURSELVES 15-20 MI S OF COURSE. WE INITIATED A 45 DEG RIGHT TURN, 320 DEGS TRUE (APPROX POS 60 44N 2416W). WE WERE BACK ON COURSE AT 61 04.8N 25W AT XX41Z. AS WE LOOKED AT OUR MISTAKE WE HAD IN FACT GONE FROM 60N 10W TO 60N 20W, INSTEAD OF 61N 20W, THEN TO 61N 30W. WE LOOKED AT THE WAYPOINT IN THE INS. IT HAD BEEN INCORRECTLY INSERTED BY THE CAPT, EVEN THOUGH HE HAD WRITTEN THE DEW CLRNC CORRECTLY ON THE FLT PLAN. NEITHER THE F/O NOR I CAUGHT THE ERROR OF 1 DIGIT. FURTHERMORE, THE FIX 10 MINS AFTER THE TURN AT 60N 10W DIDN'T REVEAL A DISCREPANCY LARGE ENOUGH TO NOTICE. THE TRACK CHK WAS WITHIN A FEW DEGS. THE INS CHK AT WHAT I THOUGHT WAS 61N 20W SHOWED US AT 60N 20W. I JUST MISSED IT, LACKING CONCENTRATION PERHAPS DUE TO FATIGUE (ONLY SLEPT 2 HRS THAT NIGHT). WE DID NOT RPT IT TO OCEANIC BECAUSE WE WERE BACK ON COURSE WITHIN A FEW MINS. ON ONE BROUGHT IT TO OUR ATTN. THE BIG QUESTION: HOW COULD WE HAVE SCREWED UP?? THE PROCS ARE GOOD, BUT WE FAILED TO PAY ATTN TO DETAILS.

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.