So…uh…I literally just sprinted around the ENTIRE length of the fence around the airfield in the Farmlands region.
It doesn’t have a SINGLE gap in it!
There were a couple higher ground / lower fence areas where I thought I’d be able to jump the fence into it, but no luck (I suck at jumping at this and all games).
Is there some sort of glitch jumping required?
Is it locked behind a story mission?
I know there’s a Safehouse in there…
Thanks in advance for any info!
The main entrance is on the north side, almost exactly on the middle I think. There is a road leading in to a gate, with some barrackses and cars stnding there.
On my first time to the airfield, I was able to jump a low section on the NW corner. 
Either jump over the fence in the southern border of the airfield, there’s some point at a little hill where you can relatively easy take a jump or fight your way through the main entrance in the northern part.
Maybe crawling below it is a thing, too !? I don’t know, back then that was not an option. 
I…must be blind.
Thanks @NJR87
I hear it’s a HUGE combat zone when inside…but I figure if I can get the Safehouse unlocked I can lure enemies back to Safehouse entrance and plink away…
Thank you!
Consoles still don’t have crawl until August update.
I tried jumping over in a few spots and failed.
It seems I somehow missed the main entrance on the north side LOL.
Hehe, the main entrance should be hard to miss! 
How many machines are at the airport can vary a lot, but there are often some machines of each type, and they’re usually FNIX class. There are lots of buildings in there for cover, and a large bunker area, with some hunters hiding in the darkness I seem to remember. 
I suppose you mean Överby Air Base. I remember running around that fence myself until I found the entrance.
There’s also a completely unguarded back entrance leading straight into the underground bunker from the outside at coordinates -1230, 980.
Right where the player icon is on this screenshot!
I made my way in through the Main entrance. You must be quick and jump in the doormans booth. In my case their was one hunter that agroed me. I showed him my passport (the KVM59) and then i stepped over his junk heap and made my way into the buildings. Through the buildings i made my way to the eastend of the Airfield without giving a shoot. then at the very end of the airfield i crossed over on the other side and made the safehouse. threw some fireworks to blind the big boys. I had some hunters on my heels but they where blindet too 
Hello Alicia, that entrance must be new. My visit was on the 8th March this year and at this side there was no entrance. but jumping over the fence is at the southwest corner possible. When you are on PC then run (W+Shift) and short before the fence hit the space bar. I slapped the hand at my forehead as i tried that. Because i had made the safehous trough the Main entrance.
why make it easy when it can be complicated:man 
You could go there and check if it’s there for you now!
Yes, i will look at that place. Yesterday i was on Ibboholmen and looked for some POI the serpentstone and the Milestones what is descibet in german. I passed that stone on Ibboholen so often but didn’t notice that. But i saw that many things been changed. Many things are new added. And i think this entrance at the airport must be new. I will in the next time ramble a little round on the map. I love this.
That back entrance, directly to the underground bunker, was in the game when i first went to the Airfield back in the April '19, so, it isn’t that new. 
But it is very easy to miss.
I think so too, I must have overlooked it, I just looked at it. But the rock face was not previously shown on the map. I could bang my head on the desk, oh my god.
Is the underground bunker in the airfield where the safe house is?
No, it is right at the koordinates that Alicia has shown. it is underneath the rockface. when you step in then you coming direct into the bunker that is on the westend of the Airfield. The safehouse is on the eastend (I must correct my post above) . When you step out the Bunker you can go through the wood on the southside and go east. You have there good abilities to hide when you get in Combat, because some bots are lurking around.
If you are within 250m of safehouse, you’ll get safehouse icon on your compass, leading you to it.
…I’m getting a feeling that you’re asking everything from forums, rather than bothering to play the game. 
I literally am in the middle of an 8 hour session.
This game has taken over my life these last few weeks.
I like these forums.
I like posting.
Why have forums if not to post to them?
Sorry…?
I’ll try to use search function more, I guess?
I have to admit honestly that I often looked at youtube in the beginning because some players filmed their missions there. Most of the time they were in multiplayer mode and of course had more firepower than me alone. But at least I could roughly see where I was going. I then had to come up with a strategy for myself how I could do it alone