Aeronautical Terms beginning with N

National defense airspace

Airspace established by a regulation prescribed, or an order issued under, 49 U.S.C. 40103(b)(3).

Navigable airspace

Airspace at and above the minimum flight altitudes prescribed by or under this chapter, including airspace needed for safe takeoff and landing.

NDB (ADF)

Nondirectional Beacon (Automatic Direction Finder).

Night

The time between the end of evening civil twilight and the beginning of morning civil twilight, as published in the American Air Almanac, converted to local time.

NM

Nautical Mile.

Nonprecision approach procedure

A standard instrument approach procedure in which no electronic glide slope is provided.

NOPAC

North Pacific Area Of Operation.

NOPT

No Procedure Turn Required.