Date: 202101
Local time of day: 0601-1200
Location: ZZZ.TRACON, US
Light: Daylight
Aircraft: Regional Jet 900 (CRJ900)
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Climb; Initial Approach; Cruise; Descent
ATC / advisory: TRACON ZZZ
Aircraft component: Autoflight System
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Flying; First Officer
Human factors: Confusion; Situational Awareness
Anomaly: Aircraft Equipment Problem Less Severe; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance
Detector: Person Air Traffic Control; Person Flight Crew
When detected: In-flight
Result: Flight Crew Became Reoriented; Flight Crew Requested ATC Assistance / Clarification
Contributing factors: Human Factors; Aircraft
Primary problem: Aircraft

Narrative: In our initial climb to 6;000 feet we were instructed by Departure to turn off course and given a fix to fly to. I confirmed the fix with the CA (Captain) and pressed Nav Mode on the FMS. I looked over to my PFD to set the new altitude assigned by Departure and the CA looked away at the same time. Shortly thereafter; Departure called and asked us if we were turning on course. We both looked up and realized that the Nav mode had not captured the course. I immediately turned the heading bug towards the course line on the display; while the CA notified the Controller that we were correcting and turning on course.While compensating for winds and flying via the heading bug; we started to analyze the problem. Shortly after changing the AP to the CA's side; we were able to correct the Nav issue; as the AP was functioning properly on the CA's side; I continued as the pilot flying. About 45 minutes out; the CA left the flight deck to use the LAV. As he returned; he noticed that we had about 8 status messages that popped up sometime after he had left the flight deck. I was engaged with a short conversation with the FA (Flight Attendant) and did not notice the display of messages until he returned. The status messages were flight control related; noting flight spoilers; rudder; etc. The CA referred to the QRH for landing data as a precautionary measure; in the event of a total system failure to those systems. The CA Then notified ATC of our potential systems status and requested deleting the LAHSO restrictions. ATC was unable to comply.Later; as we were given an intercept angle to intercept the final approach course; I selected the NAV button and was waiting for the intercept. We had a [heavy aircraft] on our left and we were paying close attention to that traffic; when we noticed that the aircraft had blown through the center line and was deviating right. The CA then asked me what was going on and while trying to process the information; I replied; 'I have no idea.' At that time Tower called to query our actions; It was as if the aircraft had a mind of its own and before I was able to kick off the autopilot; the CA then asked for the flight controls. We landed without incident and all flight control systems were operational throughout the landing phase; as all the spoilers had deployed. The AP had remained on the CA's side throughout the entire approach.Hindsight; I told the CA; that the one course of action we could have taken at the onset of discovering that the AP/Nav was not recognizing my side; we should have changed roles and allowed him to be the Pilot Flying. With the unexpected behavior of the FMS during the critical phase of flight; I was in total agreement with the CA's actions and decisions; I believe his actions were appropriate and timely while operating in the essence of safety for the passengers and crew.




Synopsis: CRJ-900 First Officer reported track deviations resulted when the aircraft's autoflight systems became unreliable.