Boris Badenov
Fortis Leader
Your situation is exceedingly unlikely to actually occur.
I didn't stipulate everything you did. I just said (or meant to say) that it's a bad day and the deice is (for whatever reason) MEL'd, and there's unforecast icing at your destination (this has happened to me numerous times...pretty sure it's not unrealistic) and you're shooting this NDB that you say you don't really have to worry about because there aren't any RAIM warnings and the Magenta Magic does all the work for you, etc. But then for whatever reason that poops the bed, too (overvoltage popped the C/B, Sunspots, whatever...again, I can personally attest to the fact that these things ACTUALLY happen, like in the real world. The most likely cause would be that the F/O in question hit the wrong buttons, but I digress).
So now you're worrying about whether the airplane will keep flying, you're suddenly on green needles (or so we called it in the Beatchjet FMS...not sure what the right terminology is in your ride, but regardless, you're flying a raw data approach). And the guy sitting next to you not only hasn't ever done an NDB to minimums on raw data, but hasn't even DONE an NDB at all, ever, and is probably trying to get the Magneta Line Of Grace back like his life depended on it (because of course in his mind it does). So now it's just you, looking at some inconveniently placed backup HSI and trying to remember which line is the bearing pointer and exactly how it was you even flew an inbound course from an ADF anyway all those years ago and hell how much ice can this thing take anyway I don't even know and crap how do you even find the FAF on this thing oh crap I have to tune a crossing radial, etc etc etc.
And I'm sure you'd carry it off. You wouldn't have gotten this far if you were a bad pilot, I suspect. But do you really think that's an acceptable level of Safety? Remember, we're talking about just two relatively common systems failures, one of which could even have happened and been legal before you took off. The whole point of having two pilots is to have two PILOTS.