For a lot of the "old" stuff (ADF, VOR, and ILS approaches with and without DME), approval to use this is implied by getting an instrument rating and an aircraft that has the equipment installed. Certainly the POH does not contain any reference to specific approvals to use the equipment as intended, indeed most POHs do not contain anything specific on this equipment.
For the newer stuff (RNP-5 / B-RNAV with GPS receivers, P-RNAV and R-NAV approaches) there are apparently four requirements: - equipment approval - aircraft installation approval - operator approval - pilot qualification (probably indirectly via requirement for operator approval)
The equipment approval is pretty clear, since ILS receivers also need to be certified, just curious where that is written down.
The requirement for aircraft installation approval is also clear, since any equipment installed is a minor/major mod. But for example, where does the requirement for the individual installation to be approved for a certain purpose come from? If I fit an ILS receiver there is no POH supplement saying "this installation is approved for ILS approaches", so why do I need this for B-RNAV, P-RNAV?
And who exactly imposes the requirement for operator approval for P-RNAV?
Yes to see how over the top it can get in Australia the pilot needs individual approach type certification (which requires annual renewal) to use each of ILS, RNAV, LLZ, VOR, NDB or GPS approaches....
Quote from CASA:
There are six navigation aids (NavAids) or procedures (Section 6.5 (b)): (i) RNAV/(GNSS); (ii) ILS; (iii) LLZ; (iv) VOR; (v) DME or GPS arrival procedure; (vi) NDB; Each navigation aid or procedure that has been satisfactorily tested, must also be entered in the person’s personal log book. Section 6.6 states: An endorsement entered in a person’s log book for a navigation aid or procedure: (a) has no time limit; and (b) may be used with any grade of instrument rating held by the person; and (c) may only be used subject to compliance with the relevant recent experience, and proficiency testing, requirements mentioned in subsection 11.
Yes to see how over the top it can get in Australia the pilot needs individual approach type certification (which requires annual renewal) to use each of ILS, RNAV, LLZ, VOR, NDB or GPS approaches....
Presumably, however, that is because Australia offers a load of sub-ICAO versions of the IR (a bit like the UK IMCR which has served thousands of pilots so well since 1969) and only the very top one is the ICAO IR.
But in Australia, this is the law, and well understood and I am sure written down somewhere.
There are lots of made-up rules that have no basis in legislation, and I am trying to find out where these rules are written down so I can - of course - follow them to the letter, or if it is NOT written down somewhere by someone with authority to make these rules, ignore them.
For example, there is an AIP entry for the UK that you need clearance to cross an airway (Class A) at its base level VFR, at right angles. This has no basis in law, it is a leftover from before the introduction of the ICAO airspace in the UK.
Recently, an IR examiner grilled me about stabilised approach criteria. They apply in EASA-OPS, not for private ops - he insisted they were universal. [In any case, I would not ignore them nor would I disagree with an examiner about trivial things like that. Where is the colour chart?].
We have police insisting on granting permission for flights within the common travel area, which is not required.
We have, all of a sudden, a universal requirement for GAR forms even at airports that are notified for immigration. Again, not sure where that comes from; the AIP entry is written in a way that requires the form for ALL flights, I am pretty sure that airlines have different procedures (which probably amount to the same).
We have aviation authorities insisting that EASA resident pilots of third-country aircraft have EASA licences, when the law clearly says operator, whoever that may be.
Hence my question - where do all these approval requirements come from? I am sure a lot of them have some basis, but I suspect not all of them
Presumably, however, that is because Australia offers a load of sub-ICAO versions of the IR (a bit like the UK IMCR which has served thousands of pilots so well since 1969) and only the very top one is the ICAO IR.
Well it has the Private IR. Which is essentially an enroute IR. The aids authorisation in Australia is over the top. But as said, it is clear how it works. The problem in Europe is that it is quite hard to know what the actual rules are.
where do all these approval requirements come from? I am sure a lot of them have some basis, but I suspect not all of them
Sorry for the comical reply but let's say the Govt set up an agency to regulate the thickness of Mars Bar wrapping paper.
They allocate a budget of GBP 10M/year, and appoint UK's best known failed ISO9000 quality manager (a former head of the Charter Institute of Failed ISO9000 Quality Managers - CIFIQM) to run it.
What do you think this chap, well rounded from all the 4 course lunches at the CIFIQM building located opposite Buckingham Palace, is going to do?
Say "this job is silly; I don't want to do it"
Recruit 100 travelling Mars Bar wrapper inspectors, each one issued with a Mitutoyo micrometer (with an individual calibration certificate, renewed every 6 months at a lab which has traceability to the National Physical Laboratory), with a company car and a final salary (1/30 rule) based pension scheme, and set them off on random inspections of sweet shops. In between that, his office will be writing to all the trade magazines "explaining" how important it is to regulate the paper thickness for everybody's "safety". The marketing managers of the calibration labs will be very happy and will be doing the same...
The examples you mention, Cobalt, is mostly people who have a mortgate to pay and a family to feed and who are as likely to read between the lines in your favour as turkeys are likely to vote for xmas. Quite a few of them are useless people who could not do a real job but even the good ones will act this way.
If you have enough money to not worry, and you have integrity, you won't be doing that, but most people live from hand to mouth, their Porsche Cayenne is on finance, and they need the money. There are also people with loads of integrity who are always decent even if they are broke but they are very rare.
Me cynical? Never 
The requirement for aircraft installation approval is also clear, since any equipment installed is a minor/major mod. But for example, where does the requirement for the individual installation to be approved for a certain purpose come from? If I fit an ILS receiver there is no POH supplement saying "this installation is approved for ILS approaches", so why do I need this for B-RNAV, P-RNAV?
And who exactly imposes the requirement for operator approval for P-RNAV?
In the UK, Arts 124 and 125 of the ANO (or their interpretation!).
