Chapter1 The National  Airspace System Introduction The  National Airspace System (NAS) is the network of  United States airspace: air navigation facilities, equipment,  services, airports or landing areas, aeronautical charts,  information/services, rules, regulations, procedures, technical  information, manpower, and material. Included are system  components shared jointly with the military. The system’s  present configuration is a reflection of the technological  advances concerning the speed and altitude capability of jet  aircraft, as well as the complexity of microchip and satellite- based navigation equipment. To conform to international  aviation standards, the United States adopted the primary  elements of the classification system developed by the  International Civil Aviation Organization (ICAO). This chapter is a general discussion of airspace classification;  en route, terminal, and approach procedures; and operations  within the NAS. Detailed information on the classification  of airspace, operating procedures, and restrictions is found  in the  Aeronautical Information Manual (AIM). 1-1