A320 PRNAV, RNAV Approach
Dear all,
A320 Fcom - PRO part - Special OPS - RNP-1 states that, in case of FMS1/FMS2 pos diff. during PRNAV operations, the pilot has to inform ATC of the loss of RNP capability.
In case of RNAV GNSS approach, Fcom - PRO - SOP - says:
"If the FMS1/FMS2 POS DIFF message is triggered during the approach, discontinue the approach, unless radio NAVAID raw data is available and indicates correct navigation to continue the approach by using the AP/FD associated to the non-affected FMGC side."
The question is: why in a RNAV approach (which is more critical than a PRNAV STAR) I'm allowed to check if one FMGC still has a good position to continue the approach, whereas in a PRNAV STAR, Fcom says I just have to inform ATC of the loss of PRNAV capability?
Last question: why in the SOP for RNAV GNSS approaches there's no guideline in case of "Check IR 1(2)(3)/FM position" message on MCDU whereas there's a guideline for this in case of PRNAV operations?
Thanks!