Date: 202010
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Aircraft: EMB ERJ 145 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Approach
ATC / advisory: TRACON ZZZ
Aircraft component: Central Computer
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Flying; First Officer
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Human factors: Workload; Time Pressure; Confusion; Distraction
Second reporter function: Pilot Not Flying; Captain
Anomaly: Aircraft Equipment Problem Less Severe; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew Became Reoriented; Flight Crew FLC Overrode Automation; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Overcame Equipment Problem
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: It was from ZZZ1 to ZZZ IFR flight. Our flight plan and clearance was from ZZZ1..ZZZZZ5. ZZZ. On the ground; [the] Captain; and I reviewed the route including every fix in the arrival and programmed [the] FMS for Runway XXL in ZZZ. From takeoff until descend via ZZZZZ 5 Arrival; flight was uneventful. Captain and I took off from Runway XXL at ZZZ1 and then instructed to go direct ZZZZZ shortly after instructed go to direct ZZZZZ1 which is [the IAF] of [the] arrival. We were instructed to descend via ZZZZZ5 Arrival in to ZZZ with both altitude and airspeed restriction as stated in the STAR. During the descend; the ZZZ Approach Controller gave instruction to switch our runway to XXR. Captain and I programmed [the] FMS and switched our planned runway to XXR as well as review the fixes along the route. However; as we approach the fix ZZZZZ2; LNAV autopilot was switched to lateral mode [and the] airplane was late to turn to [the] final [approach] fix which is ZZZZZ3. As soon as Pilot Flying noticed the mode change in autopilot; Pilot Flying used heading bug to make a left turn to rejoin the course for the rest of arrival. After the arrival; flight crew flew rest of flight uneventfully and land safely at Runway XXR. Next time; we will review the fixes more carefully after making any changes on the runways or arrivals and make sure if there are any fixes that are duplicated; we will deleted it.


Second narrative: On arrival to ZZZ we were descending via ZZZZZ5. Our dispatch release had planned [Runway] XXL and we had already briefed our approach prior to the beginning of the arrival as is common for preparation and safety. As an LCA (line check airman) I have been flying our route structure for over X;XXX hours in the left seat and this is common practice for myself. However; I am still trying to understand the traffic flows in ZZZ and as time progresses I am positive the other crews and I will get better at selecting runways based on flow and approaches utilized over time. ZZZ Approach Control gave us instructions for XXR somewhere after ZZZZZ5 I believe. I was the pilot monitoring. So I immediately went to work resetting FMS verifying ZZZZZ3 had now changed to ZZZZZ2. Altitudes were correct at said waypoint. Getting new landing data. Resetting both navigational aids for the correct runway. And since my FO (First Officer) was fairly new to the plane I began briefing his approach to him out loud; highlighting changes and re-briefing all pertinent information. It was in the middle of this brief that I heard the lateral NAV disconnection chime. The plane had entered ROL mode and within a second I and the FO were both reaching for the heading bug. He made the correction on the FGC (Flight Guidance Computer) about as quickly as anyone could. We recaptured the LNAV course to ZZZZZ2 and were given a number to call.I have been operating with this company for over X years; almost Y are as an LCA. In all my time I have never seen what I described above. After the fact I am aware of exactly what happened and I will explain and make suggestions to correct. Upon loading the runway change to XXR the FMS duplicated the ZZZZZ fix. I know this because the pilot observing told us when we got on the ground what he had witnessed and told us it was a current trend within our airline and they were trying to troubleshoot. I understand why that might happen in the mind of the FMS as it is trying to separate the arrival into parts. Initial arrival segment versus approach segment. However; reloading approaches or fielding runways changes are common in our route structure and not once in four years has this happened anywhere else. ZZZZZ4 in ZZZ2. Landing north transitions to ZZZZZ6 at 7000. Landing south your next fix might be ZZZZZ7 at 7000 for XXC. But never in four years has a reassigned runway and a reload of the approach caused ZZZZZ4 to duplicate. This is specific to ZZZ2. This is why we are just now seeing this throughout the pilot group in this airspace. I know there is verbiage within our books that states duplicated points must be removed for this very reason. However; in this event I was unable to catch the duplicated fix due to workload and I had never seen the issue before so my mental radar so to speak was focused on threats I have seen: monitoring our descent rate; monitoring speed control for arrival compliance; re-briefing navigational aid frequencies; briefing go-around and missed approach for the new runway. All the things I have seen cause errors in our flight on a normal day. So when this lateral break happened I was as stunned as the FO. I will say to his credit he corrected in the quickest fashion and made the correct adjustment for the situation. There was nothing more we could have done. I did not feel safety was at stake nor that the violation was hugely significant. I however do see that as a systemic issue the implications of this are massive and need to be corrected ASAP which is why I have my recommendations. I spoke with a sim pilot who was able to recreate the event and he confirmed what I had already suspected. Pilots need to be aware that this is common in ZZZ2. When receiving a new runway or a change to the approach. Look for duplicate fixes!


Synopsis: Air Carrier flight crew reported the FMS produced duplicate fixes during an arrival and runway change.