I would then say that since we are cleared for the ILS, that would imply that as soon you are established on the LLZ you may descend to 3000' (Initial approach altitude) and perform a straight in ILS 22, if your position after establishment can be confirmed either by other navaids or by ATC radar.
There are two sorts of approach: procedural approaches and radar vectored approaches.
For a procedural approach, you fly from an IAF proceding from point to point on prescribed tracks and/or arcs (I'll call them "legs"). The protection from terrain is guaranteed by making sure that if you fly those legs as depicted, you won't hit anything. You don't need to know where you are on the legs, as they just link waypoints at which altitude changes may occur -- you know you may descend to the next level when you have reached the next point. The procedure is 1-dimensional in that you fly along prescribed legs.
A radar vectored approach offers its protection in a different way. The controller has an RVA chart and can permit you to descend to a level consistent with the minimum altitude for your 2-dimensional position. It obviously offers more flexibility.
There is no halfway house. Procedural approaches do not permit the crew arbitrarily to say "looks like I'm now in an area where the terrain would permit a descent to 3000 ft, so down we go". Descents are only permitted on the legs of the approach as you pass points that signify altitude changes.
So when you've intercepted the LLZ on your straight in, how do you know that you can descend to 3000 ft rather than the 3200 ft MSA?
What you
want to say is "well I'm pretty sure from other navaids I'm within a few miles of the BN so that nasty terrain that I might hit below 3200 ft is well behind me. Let's go down to 3000 ft."
But that's not the way the procedural approach game is played.
Only when you reach the BN can you be sure that a descent to 3000 ft is safe, and only then on a particular track, the racetrack -- because that's the start of the approach. Otherwise, how do you know how far out you are? As far as the procedure designer is concerned, you might be 30 miles NE of the BN when you intercept the localizer (given VOR tolerances that's not unlikely if you're coming in from SKI). So the procedure has to say, "you can descend when you get to BN, and not before".
(That's a long way of saying what OzExpat said, "There is no indication on the chart of the DME distance at which one could descend from 3200 to 3000".)
In a radar environment, you're at liberty to ask the controller for you "maneuver space", wiggle your way onto the LLZ at 2500 ft (if authorised) and come straight in. But the guarantee of terrain separation comes from the controller knowing where you are in 2 dimensions. Make no mistake, if you're asking for "maneuver space" below the MSA, you
are asking for a radar vectored approach, not a procedural one.
If this procedure were to be used regularly in a non-radar environment, it would make sense to establish a direct arrival procedure. US style would be, I think, to establish a waypoint say 5 miles NE of the BN on the LLZ as an intersection with a feeder route from the SKI. You could also route direct to that point with RNAV. That would become an IAF for a direct (no PT) arrival and you'd be free to descend from 3200 to 3000 after that point. UK style would be to establish a DME arc say 5 miles outside the BN (since there's no TDME it would have to be on the SVA I guess) and allow you to join the arc to intercept the LLZ either at 3000 ft, or if that didn't work at 3200 ft with further descent once established.
I hope that's consistent with the contribution above from OzExpat (who has forgotten more about procedure design than I will ever know). He doesn't have the benefit of the real chart (EN_AD_2_ENCN_5-3 which is on the
EAD if you have the patience required to access it -- they've put it in the wrong section there in that it's under AD rather than Charts). The only substantial difference appears to be the recognition that at 3000 ft the GP intercept point is actually 0.5 mile outside BN.
Hope that makes sense.