Narrative:

While flying as first officer (PF) on a ferry flight from siauliai international airport; lithuania (eysa); we were notified by ATC that we were approximately 8 mi south of course. We checked our FMC position data page and noticed a disparity between FMC; radio and IRS position. We informed ATC that we were having difficulty with our area navigation system and requested vectors while investigating the problem. Further comparisons were made using VOR radials and DME of vortacs along our route of flight with the aircraft's FMC fix pages which confirmed the problem. We updated our FMC with the current radio position and we were able to proceed on our filed route without further incident once we confirmed our navigation system integrity with ATC. Subsequent examination revealed that our 3 IRU position were 9 mins of latitude south of the FMC radio position while our longitude was correctly depicted on both. This confirmed that an erroneous data entry was the most likely source for the error. Siauliai airport (eysa) data was not contained in our database and we manually entered the correct parking position using the latitude/longitude coordinates listed on the commercial chart plate for our parking position during initial preflight with all 3 crew members independently verifying the coordinates prior to FMC position intersection entry as per our company procedure. Prior to departure; we were particularly concerned about our navigation accuracy after hearing ATC inform another aircraft that they were 8 mi off course; and after a servicing delay of approximately 2 hours the captain decided to do a quick align and re-input the coordinates into the FMC. Although we both verified and confirmed the position prior to input; we both did not notice that the latitude and longitude values selected during the quick align were incorrect. The correct position on the commercial chart siauliai airport (eysa) plate for our parking position was listed as N55054.4 E023023.2 what the captain actually loaded; and what I mistakenly verified was N55045.4 E023023.2.since the airport was not part of our FMC database; there was not an airport reference point (arp) on the FMC position init page nor was there was an airport symbol visible on the ehsi to help confirm that our present position had now changed and was incorrect. We had input a latitude/long for the end of the runway for situational awareness and comparison; but had deleted it when we received our ATC clearance and were directed to proceed direct to a fix (mirma) after takeoff rather than the originally filed flight plan. The fix (mirma) was over 70 miles away from the airport and when the range scale was increased to view our first waypoint; the 9 NM change in relative aircraft position was not detected. Although the aircraft is equipped with a variant of the honeywell pegasus FMC; the aircraft is not GPS equipped. Having a GPS position displayed on the FMC position init page would also have presented an additional source to compare with and precluded the need to manually input a latitude and longitude as well. From a human factors standpoint; fatigue could also be considered a contributing factor. This was the second flight of the day.

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Original NASA ASRS Text

Title: FLT CREW WAS NOTIFIED BY ATC OF NAVIGATION DEVIATION.

Narrative: WHILE FLYING AS FO (PF) ON A FERRY FLT FROM SIAULIAI INTL ARPT; LITHUANIA (EYSA); WE WERE NOTIFIED BY ATC THAT WE WERE APPROX 8 MI S OF COURSE. WE CHKED OUR FMC POS DATA PAGE AND NOTICED A DISPARITY BTWN FMC; RADIO AND IRS POS. WE INFORMED ATC THAT WE WERE HAVING DIFFICULTY WITH OUR AREA NAV SYS AND REQUESTED VECTORS WHILE INVESTIGATING THE PROB. FURTHER COMPARISONS WERE MADE USING VOR RADIALS AND DME OF VORTACS ALONG OUR RTE OF FLT WITH THE ACFT'S FMC FIX PAGES WHICH CONFIRMED THE PROB. WE UPDATED OUR FMC WITH THE CURRENT RADIO POS AND WE WERE ABLE TO PROCEED ON OUR FILED RTE WITHOUT FURTHER INCIDENT ONCE WE CONFIRMED OUR NAV SYS INTEGRITY WITH ATC. SUBSEQUENT EXAM REVEALED THAT OUR 3 IRU POS WERE 9 MINS OF LATITUDE S OF THE FMC RADIO POS WHILE OUR LONGITUDE WAS CORRECTLY DEPICTED ON BOTH. THIS CONFIRMED THAT AN ERRONEOUS DATA ENTRY WAS THE MOST LIKELY SOURCE FOR THE ERROR. SIAULIAI ARPT (EYSA) DATA WAS NOT CONTAINED IN OUR DATABASE AND WE MANUALLY ENTERED THE CORRECT PARKING POS USING THE LATITUDE/LONGITUDE COORDINATES LISTED ON THE COMMERCIAL CHART PLATE FOR OUR PARKING POS DURING INITIAL PREFLT WITH ALL 3 CREW MEMBERS INDEPENDENTLY VERIFYING THE COORDINATES PRIOR TO FMC POS INTXN ENTRY AS PER OUR COMPANY PROC. PRIOR TO DEP; WE WERE PARTICULARLY CONCERNED ABOUT OUR NAV ACCURACY AFTER HEARING ATC INFORM ANOTHER ACFT THAT THEY WERE 8 MI OFF COURSE; AND AFTER A SVCING DELAY OF APPROX 2 HRS THE CAPT DECIDED TO DO A QUICK ALIGN AND RE-INPUT THE COORDINATES INTO THE FMC. ALTHOUGH WE BOTH VERIFIED AND CONFIRMED THE POS PRIOR TO INPUT; WE BOTH DID NOT NOTICE THAT THE LATITUDE AND LONGITUDE VALUES SELECTED DURING THE QUICK ALIGN WERE INCORRECT. THE CORRECT POS ON THE COMMERCIAL CHART SIAULIAI ARPT (EYSA) PLATE FOR OUR PARKING POS WAS LISTED AS N55054.4 E023023.2 WHAT THE CAPT ACTUALLY LOADED; AND WHAT I MISTAKENLY VERIFIED WAS N55045.4 E023023.2.SINCE THE AIRPORT WAS NOT PART OF OUR FMC DATABASE; THERE WAS NOT AN AIRPORT REFERENCE POINT (ARP) ON THE FMC POS INIT PAGE NOR WAS THERE WAS AN AIRPORT SYMBOL VISIBLE ON THE EHSI TO HELP CONFIRM THAT OUR PRESENT POSITION HAD NOW CHANGED AND WAS INCORRECT. WE HAD INPUT A LAT/LONG FOR THE END OF THE RUNWAY FOR SITUATIONAL AWARENESS AND COMPARISON; BUT HAD DELETED IT WHEN WE RECEIVED OUR ATC CLEARANCE AND WERE DIRECTED TO PROCEED DIRECT TO A FIX (MIRMA) AFTER TAKEOFF RATHER THAN THE ORIGINALLY FILED FLIGHT PLAN. THE FIX (MIRMA) WAS OVER 70 MILES AWAY FROM THE AIRPORT AND WHEN THE RANGE SCALE WAS INCREASED TO VIEW OUR FIRST WAYPOINT; THE 9 NM CHANGE IN RELATIVE AIRCRAFT POSITION WAS NOT DETECTED. ALTHOUGH THE AIRCRAFT IS EQUIPPED WITH A VARIANT OF THE HONEYWELL PEGASUS FMC; THE AIRCRAFT IS NOT GPS EQUIPPED. HAVING A GPS POSITION DISPLAYED ON THE FMC POS INIT PAGE WOULD ALSO HAVE PRESENTED AN ADDITIONAL SOURCE TO COMPARE WITH AND PRECLUDED THE NEED TO MANUALLY INPUT A LATITUDE AND LONGITUDE AS WELL. FROM A HUMAN FACTORS STANDPOINT; FATIGUE COULD ALSO BE CONSIDERED A CONTRIBUTING FACTOR. THIS WAS THE SECOND FLIGHT OF THE DAY.

Data retrieved from NASA's ASRS site as of January 2009 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.