Do forts operate as air bases OUTSIDE cultural borders? Meaning that you can airlift units and launch aircraft from them?

I've built one on a one-tile island outside my borders and cannot do that. Do I need a patch or something?

I believe you can only use them like that in your own territory or in a vassal's. I could be wrong about that, but that the fact that you are unable to do so kind of confirms it.

They have to be inside your cultural borders (or those of a vassal or colony) to use them as airbases.

They have to be inside your cultural borders (or those of a vassal or colony) to use them as airbases.

That's also true if you want to heal your ships.

This is surprising since I could swear I've been able to re-base air units into other civ's cities with whom i have OB (thus suggesting that this could be done with forts as well).