Plain English Meaning

A catch-all label the FAA uses for airspace areas that don't fit neatly into the regular A-through-G classifications but still affect how and where you can fly.

Full Definition

A general category used by the FAA to describe airspace classifications that fall outside the standard controlled (Class A, B, C, D, E) and uncontrolled (Class G) airspace structure. This category includes airport advisory areas, military training routes (MTRs), temporary flight restrictions (TFRs), parachute jump areas, published VFR routes, terminal areas (TRSAs), national areas (NSAs), and defense identification zones (ADIZ).