Annex 14 of ICAO 8168 and MOS 139 in Australia detail requirements for airfields. Amongst many items, the no-circling areas are drawn with reference to the runway strip and the type of approach.
From reading these documents, it appears a no-circling area covers the limits to allow up to the greater of the runway splay or the inbound segment of the straight-in approach up to 15deg (for Cat C). If there were to be an obstacle infringing this area then only a Circling Approach would be specified. In this case the western edge of the no-circling limit. Therefore the approach may indeed coincide with the western edge of the no-circling limit. In which case this is all a moot point. Could someone confirm this?
I have also found an Airservices Australia (ASA) depiction of the chart, see here:
http://www.airservicesaustralia.com/...RGGN01-135.pdf
It shows the 15deg offset. Not being familiar with these charts, there is also an arrow which I believe may be the approaching inbound track. Irrespective, even if (1) the ASA depiction is correct and (2) the assertions of some that you can't manoeuvre the aircraft because you're inside the no-circling area are correct, it can be seen that the inbound leg at some point will enter the no-circling area. Where though?..
I'm inclined to believe the Jepp and ASA circling area depictions are not truly to scale nor a perfect representation. This is perhaps what's causing confusion.
Intruder:
Given the obstacle just outside the 2.0 NM from ARGSM fix, I'd start the alignment at 2.0 NM from ARGSM.
I completly agree. Practically and to mitigate any threats, 2nm to run ARGSM is an excellent position to begin altering the flight path to be stabilised whilst also giving a wide enough buffer for EGPWS. This position is also most likely outside the no-circling area for those that still believe you can't manoeuvre. This position gives you 2.8nm to run until the threshold. I'm still after a definitive reference for between 2.8nm and 4.2nm though...
At this stage, with this example, I'm inclined to believe manoeuvring to a longer straight-in final once within the circling area 'limit' (4.2nm from threshold) is allowed (as per above reference) even if it approaches through a no-circling area, simply because a straight-in approach has been designed as per the above regs quoted.
However, the edge of this no-circling area may in fact also be the inbound leg, therefore negating this particular query. Anyone have an answer for this?