Air units should be made in the airport or the spaceport.
I did think the lack of airbases as a tile improvement in civ4/civ5 was bull. The lack of colonies in civ5 was also bull.
Let's settle for an Aerospace Complex, shall we?
An aerospace complex with capabilities of having both interplanetary transportation and spatial transportation.
Does the spaceport replace the spaceport ? Or is there a spaceport for space travel and then a airport for local planetary transportation?