Narrative:

After takeoff from atl runway 10; attempting to begin navigation on the jogor RNAV departure; the FMS experienced (or had experienced) about a 70 NM position shift showing our position to be about 70 NM west of atl when we were actually just off the departure end of runway 10. After takeoff; we flew the tower-assigned heading (about 110 degrees) and contacted departure as instructed. Departure control issued the usual clearance direct to shele; the first fix on the departure. We took the clearance; set up the FMS and began to comply but then quickly noticed the problem and requested vectors for the departure. Glancing around at instruments; my primary flight display CDI showed close to on-course but there was no course line displayed on my mfd map display. I saw the point was still on the legs page of the CDU and had the first officer set up the direct course on the FMS and execute it and select navigation mode on the fcp. Meanwhile; I selected larger ranges on the FMS map display until I could find our course which finally showed up on the 80 mile range showing our location about 70 NM west of atl and on no part of the route to mobile. A minute or so later; the amber message 'FMS dead reckoning' showing on the CDU and EFIS. We informed ATC that we needed vectors due to FMS problems and they promptly gave us vectors for the crosswind and through the downwind area and handed us off to ZTL as we climbed to 14;000 ft. We reset the FMS position and verified several points/positions with ATC before accepting further routing. Flight crew cause/narrative: no idea. Runway 10 was verified on the FMS prior to takeoff and toga was selected in position on the runway for a runway position update. I did not notice anything unusual with the map display prior to takeoff. Without knowing the cause of the problem or exactly when the position shift occurred; I'm not sure I can suggest much other than increased vigilance during preparation for takeoff; looking at the map display and white needle navigation information next to the CDI after runway update is performed (toga) in case it was to happen prior to takeoff roll.

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Original NASA ASRS Text

Title: Flight crew of a small air carrier jet suffered an approximate 70 NM map shift at or shortly after takeoff from ATL.

Narrative: After takeoff from ATL Runway 10; attempting to begin navigation on the JOGOR RNAV departure; the FMS experienced (or had experienced) about a 70 NM position shift showing our position to be about 70 NM west of ATL when we were actually just off the departure end of Runway 10. After takeoff; we flew the Tower-assigned heading (about 110 degrees) and contacted Departure as instructed. Departure Control issued the usual clearance direct to SHELE; the first fix on the departure. We took the clearance; set up the FMS and began to comply but then quickly noticed the problem and requested vectors for the departure. Glancing around at instruments; my Primary Flight Display CDI showed close to on-course but there was no course line displayed on my MFD map display. I saw the point was still on the legs page of the CDU and had the First Officer set up the direct course on the FMS and execute it and select navigation mode on the FCP. Meanwhile; I selected larger ranges on the FMS Map display until I could find our course which finally showed up on the 80 mile range showing our location about 70 NM west of ATL and on no part of the route to Mobile. A minute or so later; the amber message 'FMS Dead Reckoning' showing on the CDU and EFIS. We informed ATC that we needed vectors due to FMS problems and they promptly gave us vectors for the crosswind and through the downwind area and handed us off to ZTL as we climbed to 14;000 FT. We reset the FMS position and verified several points/positions with ATC before accepting further routing. Flight Crew Cause/Narrative: No idea. Runway 10 was verified on the FMS prior to takeoff and TOGA was selected in position on the runway for a runway position update. I did not notice anything unusual with the map display prior to takeoff. Without knowing the cause of the problem or exactly when the position shift occurred; I'm not sure I can suggest much other than increased vigilance during preparation for takeoff; looking at the map display and white needle navigation information next to the CDI after runway update is performed (TOGA) in case it was to happen prior to takeoff roll.

Data retrieved from NASA's ASRS site as of April 2012 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.