Narrative:

Flight was proceeding eastbound to europe from the USA on north atlantic track 'V' the most northern track published this day upon reaching a fix located at 58 degree 000 north 02 degree 000 west. The aircraft (autoplt coupled to INS) executed a 10 degree bank left turn, which was undetected initially by either pilot. The aircraft deviated 6.6 mi from the track prior to the crew discovering the error. Corrective action was initiated by the captain to return the aircraft to centerline, by immediately turning right to establish an intercept heading. The turn, because of an 85 KT crosswind from the south in further excursion from centerline to a maximum distance of 16 mi, once established on a proper intercept another aircraft was observed in level flight at the 4 O'clock position at the same altitude. The crew deduced that this aircraft was assigned the slot immediately to their rear and that along track separation was reduced. The captain elected to fly a 10 mi offset from the assigned track in order to insure safe separation. Once proceeding on a parallel track speed also was increased in an effort to regain along track separation. The observed aircraft also increased speed and maintain a 3 O'clock position. At this point flight reduced speed in order to keep the other aircraft in sight. Simultaneously with the above described maneuvering, flight made numerous attempts to contact the controling agency to request a lower altitude. Once contact with shanwick oceanic and scottish control was made, they were advised of the incurred delay and clearance to a lower altitude was received. The flight continued normally under radar contact to final destination. The cause of this navigation excursion may be attributed to a compounding of minor errors. The next fix after 58 north 20 west was 57 north 10 west. The first error occurred in spite of accomplishing the standard coordinate check, when the west coordinate as 100 degree 000 west vice 010 degree 000 west. This error resulted in the aircraft attempting to reverse course at station passage. The second minor error involved a F/a entering the cockpit soliciting breakfast orders at the critical time near station passage. The course and distance check would have revealed a problem without the distraction.

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Original NASA ASRS Text

Title: HEADING AND TRACK DEVIATION OVER THE NAT SYSTEM. ASSOCIATED SPEED DEVIATION. LESS THAN STANDARD SEPARATION OCCURRED WITH ANOTHER ACFT.

Narrative: FLT WAS PROCEEDING EBND TO EUROPE FROM THE USA ON NORTH ATLANTIC TRACK 'V' THE MOST NORTHERN TRACK PUBLISHED THIS DAY UPON REACHING A FIX LOCATED AT 58 DEG 000 N 02 DEG 000 W. THE ACFT (AUTOPLT COUPLED TO INS) EXECUTED A 10 DEG BANK LEFT TURN, WHICH WAS UNDETECTED INITIALLY BY EITHER PLT. THE ACFT DEVIATED 6.6 MI FROM THE TRACK PRIOR TO THE CREW DISCOVERING THE ERROR. CORRECTIVE ACTION WAS INITIATED BY THE CAPT TO RETURN THE ACFT TO CENTERLINE, BY IMMEDIATELY TURNING RIGHT TO ESTABLISH AN INTERCEPT HDG. THE TURN, BECAUSE OF AN 85 KT XWIND FROM THE S IN FURTHER EXCURSION FROM CENTERLINE TO A MAX DISTANCE OF 16 MI, ONCE ESTABLISHED ON A PROPER INTERCEPT ANOTHER ACFT WAS OBSERVED IN LEVEL FLT AT THE 4 O'CLOCK POSITION AT THE SAME ALT. THE CREW DEDUCED THAT THIS ACFT WAS ASSIGNED THE SLOT IMMEDIATELY TO THEIR REAR AND THAT ALONG TRACK SEPARATION WAS REDUCED. THE CAPT ELECTED TO FLY A 10 MI OFFSET FROM THE ASSIGNED TRACK IN ORDER TO INSURE SAFE SEPARATION. ONCE PROCEEDING ON A PARALLEL TRACK SPEED ALSO WAS INCREASED IN AN EFFORT TO REGAIN ALONG TRACK SEPARATION. THE OBSERVED ACFT ALSO INCREASED SPEED AND MAINTAIN A 3 O'CLOCK POSITION. AT THIS POINT FLT REDUCED SPEED IN ORDER TO KEEP THE OTHER ACFT IN SIGHT. SIMULTANEOUSLY WITH THE ABOVE DESCRIBED MANEUVERING, FLT MADE NUMEROUS ATTEMPTS TO CONTACT THE CTLING AGENCY TO REQUEST A LOWER ALT. ONCE CONTACT WITH SHANWICK OCEANIC AND SCOTTISH CTL WAS MADE, THEY WERE ADVISED OF THE INCURRED DELAY AND CLRNC TO A LOWER ALT WAS RECEIVED. THE FLT CONTINUED NORMALLY UNDER RADAR CONTACT TO FINAL DEST. THE CAUSE OF THIS NAVIGATION EXCURSION MAY BE ATTRIBUTED TO A COMPOUNDING OF MINOR ERRORS. THE NEXT FIX AFTER 58 N 20 W WAS 57 N 10 W. THE FIRST ERROR OCCURRED IN SPITE OF ACCOMPLISHING THE STANDARD COORDINATE CHECK, WHEN THE WEST COORDINATE AS 100 DEG 000 WEST VICE 010 DEG 000 WEST. THIS ERROR RESULTED IN THE ACFT ATTEMPTING TO REVERSE COURSE AT STATION PASSAGE. THE SECOND MINOR ERROR INVOLVED A F/A ENTERING THE COCKPIT SOLICITING BREAKFAST ORDERS AT THE CRITICAL TIME NEAR STATION PASSAGE. THE COURSE AND DISTANCE CHECK WOULD HAVE REVEALED A PROBLEM WITHOUT THE DISTR.

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.