FAA's primary mission is to provide the safest, most efficient aerospace system in the world. FAA oversees operating and maintaining this system, known as the NAS, as well as the safety of aircraft and operators. FAA operates and maintains the NAS through the following: a workforce of technicians, air traffic controllers, and other staff who work in airport towers, terminal areas, en-route centers, oceanic air traffic control centers, and other facilities, the ATC and other supporting systems and infrastructure, including ground-based surveillance radar facilities, communication equipment, automation systems, and the facilities that house and support these systems.