[1] Flight through NSAs is not prohibited and no special advance clearance or authorization need be obtained to enter them.
However, pilots of aircraft are strongly encouraged to either stay clear of NSAs or obtain prior authorization to pass through them in order to reassure the controlling agency that no threat to national security exists.
[1] On VFR sectional charts, NSAs are delimited by a heavy dashed magenta border and a special notation.
It is designed to safeguard classified, sensitive, or restricted information, equipment or materials relevant to the NNSA mission.
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