I only have access to a 2001 OMFJ chart that gives a DA of 585ft for the ILD and an MDA of 600ft for the GP inop.
I don't see how 600ft can equal a DA of 580Ft?
I'm sorry if I confused you - there is no correlation between DA & MDA. If you consider the
minimum DA & MDA to be the respective OCAs, the methodologies to derive the ILS OCA & the GP INOP OCA are entirely different.
The ILS OCA will include a height loss margin added to any obstacle that penetrates a set of assessment surfaces peculiar to
ILS. The OCA is the minimum
DA, or a minimum OCH of 200ft (Cat 1)
The GP INOP (LOC) procedure is a non-precision approach and has a minimum obstacle clearance requirement. The set of assessment surfaces are assessed differently from the ILS. The OCA is the minimum
MDA, or a minimum OCH of 250ft.