aquarium1

On A320,Carrying out a NPA which is fed in FMGS, is there any way of seeing ILS guidance too on the ISIS.

FlightDetent

Yes, just tune the frequency. Preferably using the ident code on RAD NAV pg MCDU LSK 3L.

ref: FCOM DSC-34-NAV-20 "F": STANDBY INSTRUMENTS - Landing System Function

aquarium1

But won’t this generate approach mismatch message?

sonicbum

Yes, this will trigger the "CHECK APPROACH SELECTION" MCDU message.

BizJetJock

I don't know the Airbus system, but the obvious question to me is - if the ILS is available why are you flying an NPA? And if you're flying it because the ILS is NOTAMed inop then you can get yourself in a lot of trouble if you start using an uncalibrated signal for "guidance".
Overall it sounds like a very bad idea.

FlightDetent

Although not lightyears apart, there still are a few steps between using a NOTAMed signal to fly something unpublished or forbidden and pulling out the crosshairs visible on the STBY ATT. Come on.

The OP narrative starts with having the FMGS setup for the NPA, hence the PFD indications as well as APCH mode of FD will be slaved to that primary means.

Sometimes a tech question from an eager and technically curious colleague is just that.

Nevertheless, the good advice needs to be respected. Do not fantasize beyond the published way of doing things, the techniques and procedures have been crafted for a reason. 👍

MCDU2

BizJetJock

Check/training/aircraft has a tech issue/ATC are in the process of switching the ILS on....

BizJetJock

All are missing the point of why it is a bad idea - the profile of the NPA/2D approach may be significantly different from the ILS, so you end up with conflicting information. Fly the approach you are flying!
? If it is not yet on then having the ISIS diplaying will not do anything, and if it is then why not wait 3 minutes and fly the ILS?
I fully get wanting to know what it will do for nerdy reasons, I'm right there with that one!