I hoped the circles would map the provinces that are reachable by the air wing to determine their mission area. For most short range aircraft, selecting airzones actually has no point because you will always want to have them stationed inside the region you want them to fly. I'd be glad to have my interceptors react whenever bombers are sighted in their range. The whack a mole game is something I don't want to do as the allmighty ruler. If i put 150 interceptors on Frankfurt's airport for interception duty, I don't want them to stay grounded when enemy bombers are their range because they are in the wrong airzone. I might want to restrict them to stay inside my airspace but I dont really care for arbitrary airzones.