I think the "black letter" interpretation of ENR 1.5 p 1.10(d) is quite clear. It effectively stops you from converting a S-I Approach to a Circling Approach when the S-I MDA is below the circling MDA.

That being said, I believe that there can be an unusual situation where the 3D DA is above the Circling MDA - depending on the location of controlling obstacle. I know that there are some approaches like this in the USA (see plate below), but here in Australia - I don't know. Anyway, in this scenario it is possible to convert a 3D approach to a Circling approach and remain compliant with part 1.10(d).

My two cents worth!

I think the "black letter" interpretation of ENR 1.5 p 1.10(d) is quite clear. It effectively stops you from converting a S-I Approach to a Circling Approach when the S-I MDA is below the circling MDA.

I have to take a contrary view: the subpara is looking at the extant cloud/vis, not the prescribed minima.

If the actual weather is

(a) at or better than circling requirements, then there is no problem with breaking off from the ILS and circling .. indeed, this used to be a very common procedure to get around problem wind conditions.

(b) below the prescribed circling requirements, then one is obligated to go to the miss.

I don't see the contrary view that you speak about - this is the "black-letter" interpretation of ENR 1.5 p 1.10(d)

Just to clarify; we are talking about 1.10.1d ?

If so, there is no reference to the MDA in that subpara. The second clause provides for the two options; indeed, I cannot see that your interpretation is other than inconsistent with the logical intent of the subpara ?

I guess, perhaps, that we shall have to disagree regarding interpretation of the written word on this occasion ?

Just to clarify; we are talking about 1.10.1d ?
Yes - see below

:

If so, there is no reference to the MDA in that subpara ...
No, there is no direct reference to an MDA but it does talk about a "runway approach" - this implies a MDA (2D approach) or a DA (3D approach).

That being said, this discussion is getting too convoluted for me - agree to disagree!