air t inc. operates in two industry segments, providing air cargo services to the air express delivery industry through its wholly owned subsidiaries, mountain air cargo, inc. ("mac") & csa air, inc. ("csa"), and aviation ground support and other specialized industrial equipment products and services through its wholly owned subsidiaries, global ground support, llc ("global") & global aviation services, llc ("gas"). mac & csa provide small package overnight air freight delivery services on a contract basis throughout the eastern half of the united states, puerto rico and the caribbean. mac & csa operate approximately 90 aircraft under agreements with federal express. mac and csa operate under separate aviation certifications. mac is certified to operate under part 121 & part 135 of the regulations of the federal aviation administration . this certification permits mac to operate aircraft that can carry up to 18,000 pounds of cargo. mac's principal office, and airt's corporate headqua