To look at the equipment requirements first.
There is a big difference between a requirement for certain certified and serviceable equipment to fly in certain airspace and a requirement to have certain certified serviceable equipment in order to complete a procedure that relies on that equipment.
For example and authority may require that all aircraft operating in certain airspace classes must have 75Mhz Marker beacon equipment. That does not mean that a) without a marker beacon receiver it is OK to fly in airspace of that class because there are no markers in that airspace. or b) that there will be any requirement to use the marker beacon equipment in certain airspace of that class.
That is simply that authority saying what equipment is required before flying in that airspace class.
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.
As for flying an ILS with non-FM immune equipment.
All ILS equipment is unserviceable unless is meets the requirements of Annex 10. Meaning that unless the equipment is FM immune then it can not be relied upon to fly an ILS.
Similarly information provided by a non-FM immune VOR receiver can not be relied upon because according to Annex 10 it is unserviceable.
NDB and DME equipment are not affected by the FM issue.
Can you rely on a non-FM immune VOR? - NO.
Why, because it is legally U/S.
Can you rely on a non-FM immune ILS? - NO
Why, because it is legally U/S.
There is nothing wrong with using a non-FM immune ILS or VOR in a situation where the actual position of the aircraft can be confirmed by other means eg visual. eg when training and the aircraft is in VMC but the student is behind screens.
When talking about non-FM immune VOR and ILS systems everyone seems to think along the lines of so what, the errors are mostly theoretical and as I am only using it enroute well above obstacles there will not be a problem.- Wrong!
VOR tracking is often used as the basis of procedural ATC separation. Using non-FM immune equipment could cause a loss of separation........which would be reckless would it not?
I am sure that no one here would try to fly an ILS with a U/S ILS system anywhere. For non-FM immune read U/S for IFR IMC purposes.
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As for DIY approach procedures.
Yes indeed, the 1000ft within 5nm of the aircraft requirement does not apply when approaching to land. After all at touchdown the separation is 0!. Furthermore, when completing a published approach procedure, the obstacle clearance will be at times less than 1000ftand the area taken into account far smaller than 5nm from the aircraft.
So yes indeed there is nothing stopping someone at the moment from constructing a home made procedure. If that procedure does not comply with the requirements of DOC8168 then it is very easy to say reckless operation when something goes wrong.
There is one other fly in the ointment..........the navaid used must have been approved for use as an approach aid. One can not use an enroute VOR/DME as an approach aid. Such use as an approach aid requires a survey and a calibration flight..........all very expensive.
Thus the CAA are indeed quite happy for a person to construct a homemade procedure and do the obstacle survey, non-visual aid survey, flight checking by an approved checker, design of the procedure accordng to DOC8168 by a qualified procedure designer etc etc..........all for personal use to show that the operation is not reckless endangerment!
Otherwise, you could simply have a rule that you will be visual at the enroute MSA. As I am sure you will know that system has other benifits relating to the requirements to have alternates for IFR IMC flights.
Regards,
DFC