Narrative:

We were on the graham arrival for nashville navigation was by gfms. System had worked great up to this point. As we approached graham VOR approach told us to expect a visual to runway 20R. I waited until the gfms switched to the next waypoint which was bna and then proceeded to load the approach in the box. After I made the appropriate entries approach asked if we were going direct to bna. It was then that we noticed that the autoplt was in auxiliary navigation and the auxiliary navigation light was still illuminated however, the system was not navigating to the station -- it was just drifting. It was not even holding our previous heading. I am aware of the caution about the volls arrival into bna and have experienced the same anomaly on that arrival but was not aware of problems with the graham arrival.

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Original NASA ASRS Text

Title: A B727 WITH A GFMS SYS INSTALLED HAS A TRACK DEV WHEN IT DOES NOT PERFORM AS EXPECTED DURING A REPROGRAMMING PROC.

Narrative: WE WERE ON THE GRAHAM ARR FOR NASHVILLE NAV WAS BY GFMS. SYS HAD WORKED GREAT UP TO THIS POINT. AS WE APCHED GRAHAM VOR APCH TOLD US TO EXPECT A VISUAL TO RWY 20R. I WAITED UNTIL THE GFMS SWITCHED TO THE NEXT WAYPOINT WHICH WAS BNA AND THEN PROCEEDED TO LOAD THE APCH IN THE BOX. AFTER I MADE THE APPROPRIATE ENTRIES APCH ASKED IF WE WERE GOING DIRECT TO BNA. IT WAS THEN THAT WE NOTICED THAT THE AUTOPLT WAS IN AUX NAV AND THE AUX NAV LIGHT WAS STILL ILLUMINATED HOWEVER, THE SYS WAS NOT NAVING TO THE STATION -- IT WAS JUST DRIFTING. IT WAS NOT EVEN HOLDING OUR PREVIOUS HDG. I AM AWARE OF THE CAUTION ABOUT THE VOLLS ARR INTO BNA AND HAVE EXPERIENCED THE SAME ANOMALY ON THAT ARR BUT WAS NOT AWARE OF PROBS WITH THE GRAHAM ARR.

Data retrieved from NASA's ASRS site as of July 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.