Air support tower

Air support tower is a Nod structure, this building supports the Nod air tower by providing Vertigo bombers with a place to rearm, refuel and undergo repair. Similar to the air tower, it can support four Vertigo bombers, but it is much cheaper to produce. However, it cannot construct any aircraft itself; therefore, an air tower must be built before any support towers can be constructed.

The Black Hand utilizes neither aircraft, nor these structures.

In-game
The combat support airfield was implemented in Kane's Wrath. It appears in Global Conquest games, when there were aircraft present in the strike force but no base with proper airfields. It was also freely buildable from the support structures tab, from both the construction yard and from cranes.