Narrative:

Departing dfw airport on the grabe 2 RNAV departure from runway 35L; at approximately 1000 ft my FMS CDI needle turned as it should towards the cuzen intersection. I began a shallow turn to the right when the flight director bars began turning left. I rolled wings level. The wind indicator on my pfd was showing a 128 KT wind from the southwest which coincided with the left turn given that the CDI at this point was showing the aircraft fully deflected off course to the right. The captain's pfd wind indicator was showing a 130 KT wind from the northeast. His flight director was showing a full turn to the right to correct for his wind. The FMS's were flashing a position advisory. Upon selecting the message button; it showed position correcting. We notified ATC of the FMS malfunction and were told to level off at 3000 ft. We were at approximately 3500 ft when given this altitude. The captain asked for a heading towards cuzen and we were given a 010 degree heading. I began a shallow descent while the captain troubleshot the problem. We were then cleared to maintain 4000 ft. About one minute later the FMS's found their position and everything seemed back to normal. We notified ATC we were able to navigate again and they cleared us direct to grabe intersection and up to 17000 ft. The remainder of the flight was normal and no other anomaly was experienced with the FMS. Center control advised us a telephone number to contact dfw tower. Dfw tower notified us the event was entered as a pilot deviation.

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Original NASA ASRS Text

Title: FLT CREW OF E140 EXPERIENCE TRACK DEV ON GRABE RNAV SID WHEN CAPT'S AND FO'S FMS SYSTEMS HAVE GROSS DISAGREEMENT ON WIND DIRECTION. UNCERTAIN POS RESULTS.

Narrative: DEPARTING DFW ARPT ON THE GRABE 2 RNAV DEP FROM RWY 35L; AT APPROX 1000 FT MY FMS CDI NEEDLE TURNED AS IT SHOULD TOWARDS THE CUZEN INTERSECTION. I BEGAN A SHALLOW TURN TO THE R WHEN THE FLT DIRECTOR BARS BEGAN TURNING LEFT. I ROLLED WINGS LEVEL. THE WIND INDICATOR ON MY PFD WAS SHOWING A 128 KT WIND FROM THE SW WHICH COINCIDED WITH THE LEFT TURN GIVEN THAT THE CDI AT THIS POINT WAS SHOWING THE ACFT FULLY DEFLECTED OFF COURSE TO THE R. THE CAPT'S PFD WIND INDICATOR WAS SHOWING A 130 KT WIND FROM THE NE. HIS FLT DIRECTOR WAS SHOWING A FULL TURN TO THE R TO CORRECT FOR HIS WIND. THE FMS'S WERE FLASHING A POS ADVISORY. UPON SELECTING THE MSG BUTTON; IT SHOWED POS CORRECTING. WE NOTIFIED ATC OF THE FMS MALFUNCTION AND WERE TOLD TO LEVEL OFF AT 3000 FT. WE WERE AT APPROX 3500 FT WHEN GIVEN THIS ALT. THE CAPT ASKED FOR A HEADING TOWARDS CUZEN AND WE WERE GIVEN A 010 DEG HEADING. I BEGAN A SHALLOW DESCENT WHILE THE CAPT TROUBLESHOT THE PROB. WE WERE THEN CLRED TO MAINTAIN 4000 FT. ABOUT ONE MINUTE LATER THE FMS'S FOUND THEIR POS AND EVERYTHING SEEMED BACK TO NORMAL. WE NOTIFIED ATC WE WERE ABLE TO NAVIGATE AGAIN AND THEY CLRED US DIRECT TO GRABE INTERSECTION AND UP TO 17000 FT. THE REMAINDER OF THE FLT WAS NORMAL AND NO OTHER ANOMALY WAS EXPERIENCED WITH THE FMS. CTR CTL ADVISED US A TELEPHONE NUMBER TO CONTACT DFW TWR. DFW TWR NOTIFIED US THE EVENT WAS ENTERED AS A PLT DEV.

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.