GB;
The Collins radar on the AF330 fleet is highly monitored, and since it's an essential system, any detected failure would be transmitted via ACARS so that maintenance would be prepared to fix it.
Possible undetected failures would include:
*Heavy coating of ice on the radome - highly unlikely.
*Antenna plate coming detached from its pedestal. It is attached by clamps held by two small bolts that are safety-wired. That one is pretty rare, too.
All other functions, including antenna drive position, are monitored, and hence any failure would be reported.
Water ingestion into the honeycomb structure of the radome may cause false targets, but will not get large enough to matter at altitude, once frozen.
It's been asked but I don't think answered in the thread - the radar would fail with the loss of all IRS data, (which had occurred by 02:13Z). There are two transceivers. ADIRS 1 supplies tcvr 1 with ADIRS 3 as backup, and ADIRS 2 supplies tcvr 2, with ADIRS 3 as backup.
The failure messages would be:
WXR ATT (amber) : Attitude control failure.
WXR STAB (amber) : Antenna stabilization failure.
According to the AOM, these particular messages are displayed on the ND, (nav data display). According to the A340 AMM, (I am assuming a similar installation on the A330):
Re "heavily monitored", yes it is. The BITE montors the radar system itself as well as the periherals, (EFIS CTL PNL, ADIRUs & CMC - Central Maintenance Computer). All failure messages and BITE results are immediately transmitted to the CMC. The ATA failure codes are:
RADAR Transceiver....................................34-41-33
RADAR Antenna.........................................34-41-11
RADAR Control Unit....................................34-41-12
RADAR No Data From ADIRU......................34-12-34
RADAR No Data from EFIS 1 Panel..............22-81-12
RADAR No Data from EFIS 2 Panel..............22-81-12
RADAR No Data from CFDIU........................31-32-34
I think we can assume that the radar could function up until the loss of the IRU data.
PJ2