NAVIGABLE AIRSPACE- Airspace at and above the minimum flight altitudes prescribed in the CFRs including airspace needed for safe takeoff and landing.
(Refer to 14 CFR Part 91.)
NAVIGATION REFERENCE SYSTEM (NRS)-The NRS is a system of waypoints developed for use within the United States for flight planning and navigation without reference to ground based navigational aids. The NRS waypoints are located in a grid pattern along defined latitude and longitude lines. The initial use of the NRS will be in the high altitude environment in conjunction with the High Altitude Redesign initiative. The NRS waypoints are intended for use by aircraft capable of point-to-point navigation.
NAVIGATIONAL AID- Any visual or electronic device airborne or on the surface which provides point‐to‐point guidance information or position data to aircraft in flight.
(See AIR NAVIGATION FACILITY.)
NBCAP AIRSPACE-
(See NATIONAL BEACON CODE ALLOCATION PLAN AIRSPACE.)
NDB-
(See NONDIRECTIONAL BEACON.)
NEGATIVE-“No,” or “permission not granted,” or
“that is not correct.”
NEGATIVE CONTACT- Used by pilots to inform
ATC that:
a..
Previously issued traffic is not in sight. It may be followed by the pilot's request for the controller to provide assistance in avoiding the traffic.
b.
They were unable to contact ATC on a particular frequency.
NFDC-
(See NATIONAL FLIGHT DATA CENTER.)
NFDD-
(See NATIONAL FLIGHT DATA DIGEST.)
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.
(See ICAO term NIGHT.)
NIGHT [ICAO]-The hours between the end of evening civil twilight and the beginning of morning civil twilight or such other period between sunset and sunrise as may be specified by the appropriate authority.
Note: Civil twilight ends in the evening when the center of the sun's disk is 6 degrees below the horizon and begins in the morning when the center of the sun's disk is 6 degrees below the horizon.
NO GYRO APPROACH-A radar approach/vector provided in case of a malfunctioning gyro‐compass or directional gyro. Instead of providing the pilot with headings to be flown, the controller observes the radar track and issues control instructions “turn right/left” or “stop turn” as appropriate.
(Refer to AIM.)
NO GYRO VECTOR-
(See NO GYRO APPROACH.)
NO TRANSGRESSION ZONE (NTZ)- The NTZ is a 2,000 foot wide zone, located equidistant between parallel runway final approach courses in which flight is not allowed.
NONAPPROACH CONTROL TOWER- Author-izes aircraft to land or takeoff at the airport controlled by the tower or to transit the Class D airspace. The primary function of a nonapproach control tower is the sequencing of aircraft in the traffic pattern and on the landing area. Nonapproach control towers also separate aircraft operating under instrument flight rules clearances from approach controls and centers. They provide ground control services to aircraft, vehicles, personnel, and equipment on the airport movement area.
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