I lived in Green River for Most of my life.
It's true the airspace hasn't been active for 30 some odd years.
The missile base in green river shut down many moons ago and I have no idea why they keep the restricted area on the map. The only thing I can possibly think of is they may reactivate in times of war????
All you need to do legally is check notams.(Although you probably have better odds of winning the lottery than the airspace being hot)
If it's not hot your good to go.
It's pretty simple, per the FAR part 91:
"(a) No person may operate an aircraft within a restricted area (designated in part 73)
contrary to the restrictions imposed, or within a prohibited area, unless that person has
the permission of the using or controlling agency, as appropriate."
It's pretty simple, per the FAR part 91:
only parially right nmflyguy
according to 73.13
"no person may operate an aircraft within a restricted area between
the designated altitudes and during time of designation, unless he has the advance permission of :
(a) the using agency described in 73.15; or
(b) the controlling agency described in 73.17.
So where the published "time of use is by notam 48 hours in advance" you don't need permission to use the airspace.
Fly on