Justicar, good to see some actual citations of documents to back up your argument. May I ask a question or two?
You quoted Article 49 (5)(a) and (5)(b) and concentrated on "notified instrument approach procedure", but not the 'specified... height'.
Specified is defined in (7) as
(7) In this article “specified” in relation to aerodrome operating minima means such particulars of aerodrome operating minima as have been notified in respect of the aerodrome or if the relevant minima have not been notified such minima as are ascertainable by reference to the notified method for calculating aerodrome operating minima.
There is the word 'notified' which DFC mentioned.
In 155 (Interpretation) is says
Notified’ means set out with the authority of the CAA in a document published by or under an arrangement entered into with the CAA and entitled ‘United Kingdom Notam’ or ‘Air Pilot’ and for the time being in force
Ah, there is the reference to the AIP, so the minima specified in the ANO are to be found in NOTAMS or the AIP. Surely that gives the AIP more than an advisory document status, sounds like it is where the ANO tells you to find the minima for an instrument letfown. Doesn't that make it law?
Now, getting to the AIP again
3.3.2.1 Pilots with a valid Instrument Meteorological Conditions (IMC) Rating are recommended to add 200 ft to the minimum applicable DH/MDH, but with absolute minima of 500 ft for a precision approach and 600 ft for a non-precision approach.
There is the 'but', which I think makes 500/600 absolute. Therefore, as it's referenced by the ANO as being where you find these numbers, that makes it mandatory to add 600/600ft to a published approach.
I think that's what DFC said, and it's hard to see why he is wrong. Why do you think he is?
Another question.
49 (7) has two parts. The first is
In this article “specified” in relation to aerodrome operating minima means such particulars of aerodrome operating minima as have been notified in respect of the aerodrome
I am assuming this is when there is a published IAP.
it goes on to say.
or if the relevant minima have not been notified such minima as are ascertainable by reference to the notified method for calculating aerodrome operating minima.
I assume this is when there is no published IAP, one of these DIY approaches we hear about.
So if is this is the case, where is the "notified method for calculating aerodrome operating minima" to be found? Wouldn't this determine the MDH for somebody performing a DIY instrument letdown in class G. If this is not to be found, or the calculation hasn't been made using that notified method, then is an instrument letdown below MSA actually allowed? DFC made reference to this too, that DIY letdowns below MSA are illegal.
So, my other question is, what authority does anybody have to descend below MSA if they only have an IMCR (or IR) if there is no published (notified) approach?