Thanks for the responses so far guys. I'll have to dig in the FCOM a little deeper then. There's only so much reading you can do of that incredibly narrow typeface before your head hurts!
@Roj approved
*A/C intercepts a descending leg of the Vert flt path (this is a big one, we can't press the APP button now until the active WPT is the one with a coded vertical path, otherwise it does some funky stuff)
By that do you mean you can't arm it until the vert flight path in question is the final descent.. or simply you have to be descending AND intercepting the inbound radial for this to work? I have to say that at this point, with developing knowledge of the A320, it seems to overcomplicate NPA approaches slightly.
A BLUE arrow is displayed on the ND to show where the FINAL APP conditions are met and where final descent will begin If a WHITE arrow is displayed, at least one engagement condition isn't met, FINAL APP won't engage and the a/c will not descend automatically.
When we tried this in the sim/VFD we didn't get any blue/white arrows despite the approach being programmed correctly. Is there anything which could cause that to happen in your experience?
So, if you are in a HOLD, once turning inbound, IMM EXIT, then if the next WPT is the FDP you can press APP.
That's as I thought then. So we just need to make sure the NEXT waypoint is the FDP for the approach, which in this case it wasn't.
Thanks again. It's a great aircraft, but certainly complex haha.