9.G
aterpster, it's the same like for the most of us called Jeppesen, if that's what you're referring to. BTW in your example MSA is predicated on the RNAV way point RW 18 therefore it's not sectored and logically it can't be it's not a nav aid after all. Yet MSA is quite useful if you simply climb to MSA regardless of your position as long as you're within 25 NM and above MSA you're good.
The history of MSAs evolved from the military in the days of lousy nav aids and a method to recover from disorientation without flying into a mountain while inbound to an airport (air base). I have never heard of it as an altitude to be used to climb to in the event of a loss of GPS.
Let's say I suffer a loss of GPS at F70 at MDA and at the MAP. First, I have some significant terrain to the SE although the MSA controlling obstacle is well to the NE. And, to get to 12,100 from MDA within 25 miles I must make good a climb gradient of approximately 410 feet per mile, or 6.73%. In the process I hope I don't hit lesser, but nonetheless, potentially fatal terrain.
Not a pleasant prospect unless I am flying a really high-performance jet; one that well exceeds the minimum climb performance requirements.
Or I could tune in a local VOR and figure out a much lower safe altitude than 12,100.