A321
Flight Crew Air Transport Pilot (ATP)
Troubleshooting; Human-Machine Interface; Workload
Aircraft Equipment Problem Critical
Air Traffic Control Provided Assistance; Flight Crew Diverted; Flight Crew Requested ATC Assistance / Clarification; General Maintenance Action
Aircraft; Human Factors
Dual Flight Management Guidance Computer (FMGC) reset during base leg to CAT III ILS. Total loss of all flight plans and performance; delay vectors from ATC to evaluate. QRH Procedures; because of CAT III weather conditions and unsure if we would recover the FMCG's; diverted to alternate where the weather was VFR. Thales FMS system programming that is to be fixed on the next FMS software release.
We were on a 20 mile downwind when we were cleared for the ILS with touchdown RVR reported as 1;300 FT. I entered 'no star' and inserted; then went to flight plan and started clearing. I believe there was one fix then P Poss. When I pressed clear; we lost both FMGC's. We told approach that we had lost all navigation and that we had to break off approach. We informed ATC that we had to proceed to an airport that was basically VFR. I told the First Officer to run the QRH and I would fly the aircraft. ATC came back and informed us that two nearby airports were down; but a third was up. I informed ATC that we would go there. In about 3-5 minutes; FMGC 1 came back. The First Officer running the QRH got FMGC 2 back. We were not able to get managed speed or weights back. We did a visual approach and landing. This malfunction was caused by entering 'no star' for clearing out the unneeded way points during vectors; a known software fault.
A321 flight crew experiences dual FMGC failures during approach when 'No Star' is used to clear unneeded waypoints during vectors. With CAT III approaches in use; the crew elects to divert to a nearby VMC alternate.