Pure guess here...so shoot me down....haven't looked it up....(A320 related by the way)
Could it be so that in the case of an FMGC failure (FMS), and one AP 'kicks out', that we automatically have a downgrade from CAT 3 DUAL, to CAT 1 using the remaining AP (1 or 2) and still able to continue the auto flight regime down to CAT 1 minima....
I'll get my coat lol....
F/o
Last edited by First.officer; 22nd Feb 2016 at 11:56.
Reason: Added the A320 bit!