Everett M. Greene wrote:

..


Having no experience with or data about the Helena IFR procedures,
but having experience with the high Sierras and Rockies, I would find
it hard to believe the someone would "hit some granite" without being
way out of bounds. I'd describe the terrain around Helena as gently
rolling, not mountainous. Even the mountains to the west are little
more than big hills.

Well, you need to look at the charts. It indeed is an open valley with
room for a "200 and 1/2" ILS but it has terminal routes over terrain
some 5,000 feet higher than the airport.