Silvertate, I think you doing a bit of raving.
Please explain the GNSS error "satellites not in optimum positions" you mentioned a few posts back.
And I am still not happy with a pseudo-glideslope that does not call out vertical profile errors. Do you know what the max vertical error is for the approach? And was the PNF monitoring it, all the way down the approach?
Ever heard of, or seen, Nav Performance Scales?
Do you always know the escape procedure, if the GPS loses the plot and deletes the trackline while on the approach?
Ever heard of an IRS (as explained by aterpster earlier but which you obviously missed).
And then the first thing TCAS does, is cause an inflight collision.
What nonsense.