Plain English Meaning
Everything that makes flying in the United States work as one organized system — the airspace itself, the airports, the radars and radios, the controllers and rules, and the published information pilots use. When people talk about 'the system,' this is what they mean.
Full Definition
The complete network of U.S. airspace, air navigation facilities, equipment, services, airports, charts, rules, regulations, procedures, technical information, manpower, and material used to support flight operations within the United States and over surrounding international waters where the U.S. provides air traffic services.
Context Anchor
Seen in FAA publications, air traffic control discussions, flight planning, airspace explanations, and about how move through the U.S. system.