D6, I understand this. That is what I talk of when I mean geographically possible. What I am saying is that in some airports (overseas not in Oz – see my example for Mumbai) they do not do it this way. It might be perhaps they have different rules, I don’t know. They are able to specify that some sectors can go down to below others within 10 miles. If not why not just raise the 25NM MSA to the 10NM MSA as your are approaching the airport as you will have to climb to the 10NM MSA anyhow. I would also argue if you are doing an instrument approach, you would be flying the height constraints on the approach plate, not the MSAs (except for establishing yourself at the starting point for the instrument approach of course).