Plain English Meaning

These are chunks of sky that have rules attached to them because something unusual happens there — military training, hazardous activity, security concerns, or other conditions a pilot needs to know about before flying through.

Full Definition

A grouping of airspace categories set aside for activities or conditions that place limits on flight operations, including prohibited areas, restricted areas, warning areas, military operations areas (MOAs), alert areas, controlled firing areas, military training routes, temporary flight restrictions, parachute jump areas, published VFR routes, terminal radar service areas, and national security areas.