Narrative:

We were being vectored for an RNAV visual to rwy xxl. The approach loaded in FMGC's was the ILS to rwy xyl; the first officer was the pilot flying; and he attempted to load the RNAV visual into the right FMGC. When he did this; the entire database dumped. There was no data in the navigation system whatsoever; and neither of us were able to load a new destination. I notified the controller that we had lost our navigation system; and we would be unable to shoot the RNAV visual. Since the weather was VMC and no clouds; with >10 visibility; I asked the first officer if he would be ok to get vectors to a visual approach. He said he was fine with that; and I asked the controller for vectors. The controller asked us if we needed special assistance; and I advised him that we did not; but we only had basic instruments. He told us that he would vector us toward ZZZ VOR; and then we could tell him when we had the airport in sight. We proceeded with the vectors; and visually acquired the airport. It was during this time that the first officer spent a good deal of time heads down; and that lead to some distractions. I too was distracted by the malfunction; and spend a good deal of time heads down. I noticed that the app mode was not armed at about 7;000 MSL. The first officer asked me to arm it then; and I pushed the button to arm it; but was then again distracted by a question from ATC; and I failed to press the confirm button. App mode was not armed; and at 3;000' when the first officer pressed the speed button to go 'managed' on the speed; the power and target speed went to 250 knots. The first officer; not realizing that this problem was a normal result of app mode not being selected; disconnected the auto-thrust; and proceeded to fly the visual approach with manual thrust control. He believed that he could not trust the auto-throttles; although the fmcg problem was apparently unrelated to the speed issue of not being in app mode when selecting managed speed. This additional attention to detail of flying the visual approach in manual thrust mode causes us to be high on glide-path as the first officer started to fly erroneous flight director indications. I turned off the flight directors to prevent him from being confused by the FD. The first officer corrected the aircraft onto the glide-path; however we became destabilized for a brief period below 500'; and the first officer got the rate of descent to around 1;200 FPM at 400'. We landed uneventfully. This data dump of the FMGC's concerns me because it could present be a serious problem if in IMC and minimal fuel. We had enough extra fuel to make the go around; so I would recommend going around early next time as soon as the first officer and I were not on the same page as to the use of the manual thrust; and the first officer was not comfortable flying in manual thrust. I would suggest that we practice more manual thrust visual approaches in the simulator during our recurrent training. I should have been more active in telling the first officer not to go heads down once we were in the later stages of being vectored for a visual approach. His continued efforts to figure out how to reload the database were not helpful at that point in the flight; and our goal for a stable approach would have been better served if he had stayed outside and not been working on the FMGC. Had we wanted to work on the FMGC at that late stage; we would have needed to ask for a heading or a holding pattern. I think our plan to land with a visual was a good plan; but once we committed to that plan; we should have ceased troubleshooting the FMGC's that low and that close to the airport. Also; I should have had more attention to detail in not getting distracted from arming the app mode as that caused the first officer to connect unrelated issues of navigation failure and autothrust failure as there was no autothrust failure.

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Original NASA ASRS Text

Title: An A321 FMGC dumped the primary and secondary routes when the Captain selected an RNAV Visual 13R in the Secondary Flight Plan while the First Officer was flying the VOR 13L in the Primary Flight Plan. They were able to partially recover before landing.

Narrative: We were being vectored for an RNAV visual to Rwy XXL. The approach loaded in FMGC's was the ILS to Rwy XYL; the FO was the pilot flying; and he attempted to load the RNAV visual into the right FMGC. When he did this; the entire database dumped. There was no data in the navigation system whatsoever; and neither of us were able to load a new destination. I notified the controller that we had lost our navigation system; and we would be unable to shoot the RNAV visual. Since the weather was VMC and no clouds; with >10 visibility; I asked the FO if he would be OK to get vectors to a visual approach. He said he was fine with that; and I asked the controller for vectors. The controller asked us if we needed special assistance; and I advised him that we did not; but we only had basic instruments. He told us that he would vector us toward ZZZ VOR; and then we could tell him when we had the airport in sight. We proceeded with the vectors; and visually acquired the airport. It was during this time that the FO spent a good deal of time heads down; and that lead to some distractions. I too was distracted by the malfunction; and spend a good deal of time heads down. I noticed that the APP Mode was not armed at about 7;000 MSL. The FO asked me to arm it then; and I pushed the button to arm it; but was then again distracted by a question from ATC; and I failed to press the CONFIRM button. APP Mode was not armed; and at 3;000' when the FO pressed the speed button to go 'managed' on the speed; the power and target speed went to 250 knots. The FO; not realizing that this problem was a normal result of APP mode not being selected; disconnected the auto-thrust; and proceeded to fly the visual approach with manual thrust control. He believed that he could not trust the auto-throttles; although the FMCG problem was apparently unrelated to the speed issue of not being in APP mode when selecting managed speed. This additional attention to detail of flying the visual approach in manual thrust mode causes us to be high on glide-path as the FO started to fly erroneous flight director indications. I turned off the flight directors to prevent him from being confused by the FD. The FO corrected the aircraft onto the glide-path; however we became destabilized for a brief period below 500'; and the FO got the rate of descent to around 1;200 FPM at 400'. We landed uneventfully. This data dump of the FMGC's concerns me because it could present be a serious problem if in IMC and minimal fuel. We had enough extra fuel to make the go around; so I would recommend going around early next time as soon as the FO and I were not on the same page as to the use of the manual thrust; and the FO was not comfortable flying in manual thrust. I would suggest that we practice more manual thrust visual approaches in the simulator during our recurrent training. I should have been more active in telling the FO not to go heads down once we were in the later stages of being vectored for a visual approach. His continued efforts to figure out how to reload the database were not helpful at that point in the flight; and our goal for a stable approach would have been better served if he had stayed outside and not been working on the FMGC. Had we wanted to work on the FMGC at that late stage; we would have needed to ask for a heading or a holding pattern. I think our plan to land with a visual was a good plan; but once we committed to that plan; we should have ceased troubleshooting the FMGC's that low and that close to the airport. Also; I should have had more attention to detail in not getting distracted from arming the APP mode as that caused the FO to connect unrelated issues of Navigation Failure and Autothrust Failure as there was no Autothrust failure.

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.