Plain English Meaning

A patch of airspace around a sensitive ground site — like a military base or government facility — where pilots are asked to stay out for security reasons. Most of the time the request is voluntary, but the FAA can make it a hard rule when the situation calls for it.

Full Definition

A defined area of airspace established at locations where there is a requirement for increased security and safety of ground facilities. Pilots are requested to voluntarily avoid flying through the depicted NSA. When a greater level of security is needed, flight in an NSA may be temporarily prohibited by regulation under FAR 99.7. NSAs are charted on aeronautical charts with their vertical and lateral limits.