There shall be an Assistant Adjutant General for Air, with the rank of brigadier general, who shall be an assistant to the Adjutant General and who shall be appointed and commissioned by the Governor upon the recommendation of the Adjutant General at such salary as may be provided by the annual appropriations act. Such individual shall be appointed from the active or retired list of the Air National Guard and shall have a minimum of five years’ active commissioned service in the South Carolina Air National Guard.