Narrative:

During arrival on the ldora STAR; we originally briefed runway 34R; but were given 35L on check in with approach. Center had us go fast on the arrival and assigned 300 kts or better until advised so time was reduced for checklists and arrival changes. I; the pm (pilot monitoring); changed the runway in the FMS and linked it from the ldora arrival; it looked correct and the PF (pilot flying) verbally verified the change before I executed it in FMS 1. After passing the ldora fix; the airplane did not follow the FMS course and I reached up and hit heading mode on the fcp (flight control panel) and turned to an intercept heading and notified the PF that we were not on course. A few seconds later ATC must have seen us overshooting and gave us a heading back to intercept. We immediately dialed in the new heading and intercepted with no further errors. It was later discovered that in our dual FMS airplane that the FMS's were not synced properly and the change I made in FMS 1 did not duplicate in FMS 2; and we did not realize the error in time to correct before overshooting course.the root cause was a flight equipment deviation that was not properly discovered or verified by the flight crew. Contributing factors were the preconceived notion the flight equipment had been set up properly before the flight by maintenance and or another crew. This is not something we are required to check every flight (FMS sync) and some of our company airplanes have two FMS's and others only have a single FMS installed.to avoid this error in the future I will make sure to check that each FMS is synced properly in dual FMS aircraft.

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Original NASA ASRS Text

Title: CRJ-200 Captain reported a track deviation occurred on the LDORA STAR into DEN; citing lack of FMS synchronization as contributing.

Narrative: During arrival on the LDORA STAR; we originally briefed Runway 34R; but were given 35L on check in with approach. Center had us go fast on the arrival and assigned 300 kts or better until advised so time was reduced for checklists and arrival changes. I; the PM (Pilot Monitoring); changed the runway in the FMS and linked it from the LDORA arrival; it looked correct and the PF (Pilot Flying) verbally verified the change before I executed it in FMS 1. After passing the LDORA fix; the airplane did not follow the FMS course and I reached up and hit Heading mode on the FCP (Flight Control Panel) and turned to an intercept heading and notified the PF that we were not on course. A few seconds later ATC must have seen us overshooting and gave us a heading back to intercept. We immediately dialed in the new heading and intercepted with no further errors. It was later discovered that in our dual FMS airplane that the FMS's were not synced properly and the change I made in FMS 1 did not duplicate in FMS 2; and we did not realize the error in time to correct before overshooting course.The root cause was a flight equipment deviation that was not properly discovered or verified by the flight crew. Contributing factors were the preconceived notion the flight equipment had been set up properly before the flight by maintenance and or another crew. This is not something we are required to check every flight (FMS sync) and some of our company airplanes have two FMS's and others only have a single FMS installed.To avoid this error in the future I will make sure to check that each FMS is synced properly in dual FMS aircraft.

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.