Camp Grayling is one of the known FEMA Detention facilities.
I am between two of the others.. Kincheloe and Raco.
Oddly enough,, I have heard large transport planes landing at night just recently..
There is no airport in the area that would handle such traffic.. The Sault Airport handles small aircraft.
Kincheloe is the wrong direction and farther away.
Raco,, is suspect...
Large, jet aircraft,,, and engines spooling down,, in an area with very little air traffic and no (known) military bases.
Odd.