Barkingmad: Smash Bugger
Thank you for your inputs. As is often the case on PPRUNE this is spiralling into more and more arcane postings.
The original poster asked a very simple question relating to Airbus procedures.
I attempted to give a concise, simple reply. I am deeply sorry if my precis has failed to fully cover all the variations that exist between different operators and equipment fits. The general principle holds as to the reasons for the procedure nevertheless.
SB - perhaps you have only seen the Airbus with full twin GPS enabled capabilities? I had the good fortune/misfortune to fly the Airbus models from their inception and with an overlay NDB/VOR approach then the A/P does indeed disconnect at MDA-50
My reading of the OP was a question of why in manual flight does the F/D go off for an NPA and stay on for an ILS. My initial reply still answers that!