Operating cost (to the airport) of VOR DME NDB or ILS, and LPV?

I think the problem is that most commercial operators (who tend to be lucrative customers in terms of landing fees) can’t fly GPS approaches, but they can all fly an ILS.

Also they can all fly an NDB or VOR approach whose existence may be almost useless (e.g. the Shoreham EGKA MDA is such that you could just do a DIY descent out over the sea) but it legalises their use of the airport in “officially IFR” conditions.

This is obviously why Gloucester EGBJ has just put in an ILS. Not LPV! Virtually nobody in the UK can fly an LPV, legally or practically. The figures circulating, from vague memory, for the ILS installation, are well north of £1M. However EGBJ has a very good (and wealthy) catchment area and benefits from the closure of another airport which had a lot of passenger traffic. But also almost every half decent spamcan with a radio and a CDI can fly an ILS.

And only a % of the private community can fly a GPS approach. I don’t what it is overall but where I am based it is probably only about 5-10% of the privately owned (including syndicated) fleet. There are some schools and I know for a fact that most can’t fly one legally or even practically. I think only one, an FTO with some DA40s and DA42s, can fly them.

You keep saying that but I wonder what your source is.

Observation

I have never seen an IFR aircraft for hire or training here that was not equipped for RNAV approaches

It evidently depends on what you mean by " IFR aircraft for hire". The vast majority of hire planes in the UK are low grade spamcans used for PPL training. Most of them have some combination of VOR or ADF or DME and in the absence of required approach approvals these can be used to fly any applicable approach. A few have a GNS430 but almost none of them have the AFMS etc so can’t do it legally (whether this matters is always going to be debatable ). The SR22 syndicates had all the gear but they have AFAIK all collapsed and in any case were £300/hr+. There is a small number of nice planes for hire from the FTOs, but one FTO I know has stopped renting out its DA42s because – they told me this – the renters kept breaking bits on it. There are also some nice privately owned planes available for hire – e.g. my TB20 used to be – but these are rare.

The IMCR or IR syllabus in the UK does not require GPS approaches. A school or an FTO doesn’t need any GPS gear. If the plane has a GPS, fully approved etc, the IRT examiner is entitled to require it to be demonstrated, but the FTOs tend to leave an expired database in it and then they don’t need to train for this. I have that from a well placed source, too.

I would say the TBM and PC12 fleet is all GPS capable. The King Air fleet is very variable. I see a lot of them. The private ones can be very nice. But the the AOC ones tend to be really basic and shagged, very high-hour types. Private business jets should be GPS capable, AOC ones less so, and 737 and bigger jets are often not (officially) GPS approach capable at all.

The Islander ops (pic above) to the Channel Islands are a notorious example, but somehow they kept going. They work IMHO only because they can safely scud run underneath almost any wx, over the open sea. There is no way they can do VMC on top except by luck and on a nice day. They would never work inland.

Perhaps things are different in Germany.

an EASA thing, the same installation would have been ok for nonprecision approaches in an N reg

Almost certainly not legal in an N-reg either

And perversely it is easier to legalise this in an EASA reg than in an N reg, today, in Europe. With the former, you just throw some €€€ to EASA. With the latter it is a whole lot more complicated unless the GPS has an AML STC and an AFMS authorising all that.