There has been so much 737-techie stuff lately on this thread and
whether this is linked to that or
something else dropping out will annunciate what ...
While I cannot comment on such debate as I am not 737-qualified, I am a Boeing (747) man and surely, the basics are:
1) An automatic approach must always be monitored against the raw data by the PF (indeed I favour shadowing the stick & thrust levers)
2) Any failure should result in PF hand flying (if necessary) until the fault is corrected
3) If there is time, the automatics can be re-instated by PNF, otherwise
4) Revert to a hand-flown approach and landing, or
5) Accomplish a manual go-around.
One thing appears to me to be coming through time and time again - practically an obsession with getting the automatics back "in" to avoid a manual landing. Why? Is it really because many pilots are losing their basic skill set and are prepared to almost risk the safety of the aircraft trying to re-instate A/P A/T ILS LAND, rather than take what should be a welcome opportunity to manually fly and even manually (shock! horror!) land their own aircraft ... ?
I have always believed (and trained) that automatics are there as an aid to the pilots - not as an end in themselves.
... or is it just that I am getting more like Victor Meldrew every day ...
JD