Narrative:

Dfw approach initially assigned runway 17L which was programmed in FMS. Approach later assigned runway 17C. As this was being entered; the cedar creek 6 arrival dropped out of the FMS flight plan. While re-entering the aircraft started a right turn off the cedar creek 6 arrival. PF was first officer and he re-entered FMS arrival while manually re-correcting left to course. The approach controller asked if we were turning; we said the change of runway assignment messed up our FMS and we corrected. There was no conflict of traffic and rest of flight was continued uneventfully. This is a reoccurring thing at dfw. When runways are changed; sometimes all or part of the arrival route will drop out of the FMS at a very critical time.

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Original NASA ASRS Text

Title: AN ACR ACFT'S RWY ASSIGNMENT WAS CHANGED FROM DFW RWY 17L TO RWY 17C. DURING FMC PROGRAMMING THE ARR STAR TRACK DROPPED OUT. A TRACK DEVIATION RESULTED.

Narrative: DFW APPROACH INITIALLY ASSIGNED RWY 17L WHICH WAS PROGRAMMED IN FMS. APPROACH LATER ASSIGNED RWY 17C. AS THIS WAS BEING ENTERED; THE CEDAR CREEK 6 ARR DROPPED OUT OF THE FMS FLT PLAN. WHILE RE-ENTERING THE ACFT STARTED A RIGHT TURN OFF THE CEDAR CREEK 6 ARR. PF WAS FO AND HE RE-ENTERED FMS ARR WHILE MANUALLY RE-CORRECTING LEFT TO COURSE. THE APCH CTLR ASKED IF WE WERE TURNING; WE SAID THE CHANGE OF RWY ASSIGNMENT MESSED UP OUR FMS AND WE CORRECTED. THERE WAS NO CONFLICT OF TFC AND REST OF FLT WAS CONTINUED UNEVENTFULLY. THIS IS A REOCCURRING THING AT DFW. WHEN RWYS ARE CHANGED; SOMETIMES ALL OR PART OF THE ARR RTE WILL DROP OUT OF THE FMS AT A VERY CRITICAL TIME.

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.