2023-01 · NASA ASRS report 1969673
A320 flight crew reported a FMGC 1 malfunction in flight that also affected the IR. The flight crew followed the FMGC failure procedure; which led to the autothrottles being unavailable during the landing.
While in cruise flight from ZZZ1 to ZZZ; FMGC 1 had a partial failure. The system would not show information pertaining to the time or predictive details of the flight. The Captain was the pilot monitoring in this case; so the Captain gave me both the flight controls and the radios. The Captain proceeded to do both the short and long resets of the FMGC 1. The reset of FMGC 1 was unsuccessful. The FMGC seemed to reset itself several times in flight and almost come back to functioning as normal; but eventually stayed in the partially failed condition. The Captain then wrote up the FMGC and sent a message to Maintenance about its condition. While reviewing the procedure we revived an IR (Inertial Reference) 3 position error message on the FMGC 1. Then we determined that the IR position was drifting a bit but was within acceptable limits. Shortly afterward we received a similar error about IR 2. We made the same determination about this system that it was within limits. We talked about possible issues with navigation and how we would handle it if they arose. We continued to watch the systems and brief the approach into ZZZ for [Runway] XXR. We determined that we would only use AP2 (Autopilot) on the approach and that we would continue to watch the systems for any other errors. No other errors seemed to appear on the descent and the first half of the approach. As we reached approximately 500 ft. on the approach; I disconnected the AP and started to hand-fly the aircraft. At this time the Captain noted that the speed bug had vanished. I continued to fly and noticed that the speed was beginning to drop off. I then noticed that the GS was beginning to show that we were low. I pitched the nose up to correct but the speed continued to drop. At that moment the GS warning came on; the Captain said to kick off the AT (Autothrottles); and I disconnected the AT and added power. After the descent was stabilized; I reestablished visually on the PAPI and landed the aircraft without further incident. Upon touchdown and rollout; the TERRAIN TERRAIN PULL UP EGPWS went off. Unsure what had caused this at the moment; I attributed it to the issue with the FMGC and we continued with the landing. After we landed; we were confused as to what happened; but decided to investigate it when we got to the gate. After parking at the gate and shutting down the aircraft; we went back over the events of the flight in an effort to determine what had happened. We then re-read the FMGC failure procedure and noted that the last page had a note that the AT would not work once the AP was turned off. We took a moment to think about how we could have missed this; noting that several other messages had popped up during the procedure; and the system had come back and failed several times during the flight. We made sure the FMGC was noted in the logbook and informed Maintenance before departing the plane.The fact that there had been several issues that popped up during the flight led to checklists and procedures to become interrupted. In the future I will be sure to get out my QRH and look at the procedure also; if the situation allows for it. The procedure was a very long one. It is very easy to become distracted by multiple situations accumulating. If I am ever in a similar situation; while in cruise flight where the task saturation is lowered; I will also get out my QRH and follow along with what is happening.
While in cruise flight from ZZZ1 to ZZZ; FMGC 1 had a partial failure. The system would not show information pertaining to the time or predictive details of the flight. I was the pilot monitoring in this case; so I assigned the FO (First Officer) to work both the flight controls and the radios. I reviewed the Single Latch with AP (Autopilot) and FD Still Available in Managed Modes on Both Sides" QRH XX - XX but in the process the FMGC 1 came back online; although temporary. It then failed again and I proceeded to do both the short and long resets of the FMGC 1. The reset of FMGC 1 was unsuccessful. The FMGC seemed to reset itself several times in flight; and almost come back to functioning as normal; but eventually stayed in the partially failed condition. I then wrote up the FMGC and sent a message to Maintenance about its condition. While reviewing the procedure we received an IR (Inertial Reference) 3 position error message on the FMGC 1. We determined that the IR position was drifting but was within acceptable limits. Shortly after; we received a similar error about IR 2. We made the same determination about this system that it was within limits. We backed up all navigation conventionally using manually tuned VORs and advised ATC that if we were off course; to advise us.We talked about possible issues with navigation and how we would handle it if they arose. We continued to watch the systems and brief the approach into ZZZ for [Runway] XXR. We determined that we would only use AP2 on the approach and that we would continue to watch the systems for any other errors. No other errors seemed to appear on the descent and the first half of the approach. As we reached approximately 500 ft. on the approach; the FO disconnected the AP and started to hand-fly the aircraft. At this time I noted that my speed bug had vanished. The airspeed was decreasing and the FO was getting low on the glideslope. The AT (Autothrottles) were not being responsive so I asked the FO to disconnect the autothrust and add power. The descent was stabilized and the FO landed normally and on speed without AT. After we landed; we were confused as to what happened; but decided to investigate it when we got to the gate. After parking at the gate and shutting down the aircraft; we went back over the events of the flight in an effort to determine what had happened.We then re-read the FMGC failure procedure and noted that the last page had a note that the AT would not work once the AP was turned off. We took a moment to think about how we could have missed this; noting that several other messages had popped up during the procedure; and the system had come back and failed several times during the flight. We made sure the FMGC was noted in the logbook and informed Maintenance before departing the plane. FMGC failures do not occur often and [I] have never been trained of this particular event in the simulator. When the FMGC acted normally; albeit briefly; I suspect I stopped reviewing the entire procedure."
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.
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