Narrative:

On the arrival into ZZZ we were past zzzzz and approaching ZZZZZ1 when the FMS seemed to lose its position. It displayed amber dashed lines on the distance remaining location on the pilot flying pfd and the vertical profile displayed the aircraft prior to zzzzz even though we had just passed it. As we approached ZZZZZ1; the FMS did not sequence and the aircraft continued the previous course without making the turn. Both the pilot flying and pilot monitoring FMS needles on the HSI displayed previous course information and did not sequence for the turn. I immediately disconnected the autopilot and autothrottles and hand flew the depicted turn while the pilot monitoring informed ATC of the FMS malfunction. We were subsequently issued vectors and an assigned heading. During the course deviation; we remained within 3 miles of the depicted course on the mfd. This event appears to be caused by a navigation anomaly in the FMS and is unlike any other known FMS issues. Usually when an error like this is noted with and HSI being 'frozen'; the pilot flying HSI still functions normally. In this case; both pfd needles were frozen and the error occurred during descent; whereas previous cases the error has normally occurred on climb or departure. I recommend further research be conducted to see if this type of error has been occurring throughout the fleet and try to pinpoint a cause. This type of event could have been very dangerous had we been on another arrival and if the deviation would have occurred in the other direction nearer to other arrival corridors.

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Original NASA ASRS Text

Title: ERJ-175 Captain reported that during descent the FMS lost its position with both pilots needles on the HSI displaying previous flight information.

Narrative: On the arrival into ZZZ we were past ZZZZZ and approaching ZZZZZ1 when the FMS seemed to lose its position. It displayed amber dashed lines on the distance remaining location on the pilot flying PFD and the vertical profile displayed the aircraft prior to ZZZZZ even though we had just passed it. As we approached ZZZZZ1; the FMS did not sequence and the aircraft continued the previous course without making the turn. Both the Pilot Flying and Pilot Monitoring FMS needles on the HSI displayed previous course information and did not sequence for the turn. I immediately disconnected the autopilot and autothrottles and hand flew the depicted turn while the Pilot Monitoring informed ATC of the FMS malfunction. We were subsequently issued vectors and an assigned heading. During the course deviation; we remained within 3 miles of the depicted course on the MFD. This event appears to be caused by a navigation anomaly in the FMS and is unlike any other known FMS issues. Usually when an error like this is noted with and HSI being 'frozen'; the pilot flying HSI still functions normally. In this case; both PFD needles were frozen and the error occurred during descent; whereas previous cases the error has normally occurred on climb or departure. I recommend further research be conducted to see if this type of error has been occurring throughout the fleet and try to pinpoint a cause. This type of event could have been very dangerous had we been on another arrival and if the deviation would have occurred in the other direction nearer to other arrival corridors.

Data retrieved from NASA's ASRS site 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.