Went to do a diversion rebel op where you deactivate two antennas, and when I deactivated the first one, it gave me basically 1 minute to either drive or fly 1.2km into a fully fortified unidad base. I wouldn't mind if I had like 2 or 3 minutes, but 1 minute is not nearly enough. It took me 30 seconds just to get there, and that was in a chopper. Of course as soon as I landed inside the base, they spotted me and shot me to death, and I failed the side mission. Please take a look at the video below and you'll see what I mean.
I play on PC, but use a xbox controller for this game.
There's your problem, you're landing INSIDE of the base. Almost directly next to the antenna there should be a little doorway in the wall you can pass through, so it's best to just crash land your helicopter just outside the base in the little fenced of area and sprint in. I didn't have any trouble doing it that way and I found the time we had to be sufficient enough.