Hello, below are two excerpts from the "Thales New FM Pilot's Guide, Release 1A - Airbus 318/319/320/321". This is dependent on what OPC your company installed, but I would bet this is a pretty standard install world wide. The system self evaluates continuously, if the accuracy downgrades you will get a status message which is not clearable, therefore I would say no, you do not need to monitor the GPS primary feature.
Regards,
Nav Accuracy check
Refer to Operator's SOPs. Following procedures recommended, depending on availability of GPS:
l If GPS available: On PROG page,
GPS PRIMARY................. Check When GPS PRIMARY is shown (green), the Accuracy is invariably HIGH.
If "GPS PRIMARY LOST" (amber) appears in scratchpad and on ND, proceed as for GPS not available. ND message is not clearable.
POSITION ACCURACY
The following data related to Position Accuracy are displayed on the PROG page:
GPS Status [5R]
GPSOPT [OPC] [A/C CONF]
OPC: GPS Option activated
For non GPS A/C this field is blank.
When both GPS accuracy and integrity requirements are met, the Confidence Status on GPS (autonomous system) or GPIRS (hybrid system) position is designated as GPS PRIMARY, displayed on PROG page [5R].
III_083_011_SA_00
If these requirements are not met, field [5R] is blank and GPS/IRS mode is lost; "GPS PRIMARY LOST" message (amber) is triggered on MCDU and ND of the affected side. It cannot be cleared from ND. When GPS/IRS mode is restored "GPS PRIMARY" message (white) is triggered on MCDU and on ND; GPS PRIMARY is again displayed in [5R].