DFC
As is often the case, you mix up real stuff with your imagination, making it all sound very authoritative. I just hope that you are not an instructor! I have known a number like that; they make up stuff as they go along, all very convincing.
In general in Class G, no equipment is required. However, if you decide to fly IFR in IMC with no serviceable certified nav equipment and either infringe airspace or have a CFIT or near CFIT accident, or get lost and run out of fuel then it probably goes without saying that the operation was reckless.
The above is an example.
In any discussion of what is legal, one must totally separate what is
legal, and what is
sensible. Otherwise, the discussion descends into something totally pointless.
If you want an example of "reckless" look no further than the standard practice in the flight training industry where people go off flying having checked their fuel on board purely by reference to a piece of paper back at the school.
Can you rely on a non-FM immune VOR? - NO.
Why, because it is legally U/S.
Then, close down all flying schools. They train with non-FM VORs all the time
Reference please for the words "legally U/S".
One can not use an enroute VOR/DME as an approach aid
Reference please, applicable to private flight.
JonWhitehouse
Very true about not going below the MSA but you have to land eventually. Obviously one would rather land at a proper airport with an ILS or whatever, but the point is that it is
legal to fly a DIY instrument approach.
It goes without saying that one must do it very carefully but that is a whole different point.
One day, probably after a lot of the CAA have retired on their generous civil service index linked pensions, we might get GPS approaches into airfields that currently have no approach at all (and have no ATC which is a requirement for any published approach at present). Then, these discussions will be as moot as they are in the USA right now.