Air Force

An air force, also known as an air army, is in the broadest sense, the branch of a miltary that primarily conducts aerial warfare. Typically, air forces are responsible for gaining control of the air, carrying out strategic and tactical bombing missions and providing support to ground forces.

Typically an air force is only found in societies between TL D and TL 2, since prior to TL D a society will usually not have the means to travel through the air   but and after TL 2 the "air force" would be superceeded by an "air and space force" or simply "space force".

For more information see the wikipedia article Air Force.