Airfields act as a Spawn Point for aircraft. These are dotted over the map and are recognizable with a white Airplane symbol. They usually have an Army Base close by along with numerous civilian buildings, a Control Tower which doubles as a Spawn Point for Para Infantry and occasionally a depot. Airfields have very heavy AI.
Airfields have their own capture building, the Airfield Bunker.
Airfield Bunker/Radio Room
These are created as a PPO from the Supply Truck, and are deployed to reduce the distance to a friendly Airfield in order to resupply/RTB.