Date: 201203
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Weather elements / visibility: Turbulence; Rain; Fog; 3
Light: Daylight
Aircraft: Airbus 318/319/320/321 Undifferentiated
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Initial Approach
Airspace: Class B ZZZ
ATC / advisory: TRACON ZZZ
Aircraft component: FMS/FMC
Component problem: Failed
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Workload
Second reporter function: Captain; Pilot Not Flying
Anomaly: Aircraft Equipment Problem Critical
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Diverted
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: I was pilot flying. Being radar vectored on base leg for the ILS. Aircraft configured flaps 2; 180 KIAS; and weighing around 169;200 LBS. I 'cleaned up' the approach as usual by clearing the STAR to populate the intermediate waypoints on the instrument approach. Did not get the expected results and asked the Captain to 'clean up' the approach for me. At this point all NAV info was lost. FMS went blank with PPOS with blank lines. No info in secondary flight plan; RAD NAV; or anywhere else; map not available on ND with PFD normal. [We] tried to restore localizer with manual RAD NAV page and manual hard tune on RNP with no luck. Autopilot; autothrust and normal aircraft control present. I was assigned pilot flying duties since I was flying at the time. The Captain told Approach of NAV failure and we were radar vectored to assess situation. We had to abandon the approach due to lack of NAV capability and weather of 300 BKN and 3 miles in rain. Approach Control told us of local weather around nearest airports. Captain called Operations to advise situation. We conferred and came to a mutual decision to divert due to lack of navigational capability to shoot an instrument approach. Divert airport's weather was VFR. [We] landed safely without incident. All NAV was lost when approach 'clean up' was attempted second time. IRS realigned on ground in divert airport and all NAV/GPS systems returned to normal. [We] flew the same aircraft for three more flights and approaches. This time in VFR conditions; tried exact same procedure to 'clean up ' approach by clearing STAR and it worked like it was supposed to; EVERY time. Investigate this possible FMS/NAV glitch on Airbus Fleet. I have heard of this happening to other people; but am not sure if they had 'enhanced' airplanes like we did. Include alternate radio NAV aide tuning in Pilot Handbook for quick reference during situations like this. Also; don't allow Chief Pilots to question Captain's decision to divert and state that 'our policy is not to divert'.


Second narrative: On heading to intercept ILS; attempted to clean up flight plan i.e. sequence the approach. We lost navigational ability; a few moments later both ND's showed map not available. Diverted to the nearest suitable VFR airport. After lengthy conversations with Maintenance and two check pilots could not determine a cause or a fix.


Synopsis: Airbus flight crew experiences loss of all navigational capability during approach while attempting to clean up the flight plan. Both FMGC's fail along with the ability to manually tune a nav aid. Flight diverts to a VMC airport.