Actually, you can achieve close to a true pause, including FREEZING TIME.
Hit the Esc key and IMMEDIATELY save the game. When you reload the game, you will be back at the exact GPS position, plane attitude and speed as when you invoked Active Pause by hitting Esc, with a few seconds lost before you save the flight parameters. Giving the normal vagaries of flying with variable winds and all that jazz, what’s a few seconds of time lost saving the game? Anytime I want, I can return to flying from a certain position in Mann Gulch at 1:34 pm. Since I’m just playing around with free flight, perhaps I don’t really appreciate if one is losing anything relative to flight plans, etc. But having an .FLT file allows me to return to the same instant of flying over and over again as far as I can tell.
Too bad they closed the related thread for this topic: [HOW-TO] How to actually PAUSE the sim! since maybe my suggestion is the real answer to that “guide.”