I personally suppose that this scenario brings the pilots to fly by raw data only.
- How are you going to use "Raw Data"? No ADIRS = no ND as far as I can see, and even if fitted / serviceable, no DDRMI
- How are you going to use GPS? You will have raw Lat/Long information only I think - great to try and "navigate by"
From a quick think, you are basically into "looking out of the window" or "ask the nice ATC man" to help you out
NoD