NAS -- NUMEROUS TARGETS VICINITY (LOCATION)
NAS- (See NATIONAL AIRSPACE SYSTEM.)
NAS STAGE A- The en route ATC system's radar,
computers and computer programs, controller plan
view displays (PVD's/Radar Scopes), input/output
devices, and the related communications equipment
which are integrated to form the heart of the
automated IFR air traffic control system. This
equipment performs Flight Data Processing (FDP)
and Radar Data Processing (RDP). It interfaces
with automated terminal systems and is used in
the control of en route IFR aircraft.
(Refer to AIM.)
NATIONAL AIRSPACE SYSTEM- The common network of
U.S. airspace; air navigation facilities, equipment
and services, airports or landing areas; aeronautical
charts, information and services; rules, regulations
and procedures, technical information, and manpower
and material. Included are system components shared
jointly with the military.
NATIONAL BEACON CODE ALLOCATION PLAN AIRSPACE-
Airspace over United States territory located
within the North American continent between Canada
and Mexico, including adjacent territorial waters
outward to about boundaries of oceanic control
areas (CTA)/Flight Information Regions (FIR).
(See FLIGHT INFORMATION REGION.)
NATIONAL FLIGHT DATA CENTER- A facility in Washington
D.C., established by FAA to operate a central
aeronautical information service for the collection,
validation, and dissemination of aeronautical
data in support of the activities of government,
industry, and the aviation community. The information
is published in the National Flight Data Digest.
(See NATIONAL FLIGHT DATA DIGEST.)
NATIONAL FLIGHT DATA DIGEST- A daily (except weekends
and Federal holidays) publication of flight information
appropriate to aeronautical charts, aeronautical
publications, Notices to Airmen, or other media
serving the purpose of providing operational flight
data essential to safe and efficient aircraft
NATIONAL ROUTE PROGRAM (NRP)- The NRP is a set
of rules and procedures which are designed to
increase the flexibility of user flight planning
within published guidelines.
NATIONAL SEARCH AND RESCUE PLAN- An interagency
agreement which provides for the effective utilization
of all available facilities in all types of search
and rescue missions.
NAVAID- (See NAVIGATIONAL AID.)
NAVAID CLASSES- VOR, VORTAC, and TACAN aids are
classed according to their operational use. The
three classes of NAVAID's are:
a. T- Terminal.
b. L- Low altitude.
c. H- High altitude.
Note: The normal service range for T, L, and
H class aids is found in the AIM. Certain
operational requirements make it necessary
to use some of these aids at greater service
ranges than specified. Extended range is made
possible through flight inspection determinations.
Some aids also have lesser service range due
to location, terrain, frequency protection,
etc. Restrictions to service range are listed
in Airport/Facility Directory.
NAVIGABLE AIRSPACE- Airspace at and above the
minimum flight altitudes prescribed in the FAR's
including airspace needed for safe takeoff and
(Refer to FAR Part 91.)
NAVIGATIONAL AID- Any visual or electronic device
airborne or on the surface which provides point-to-point
guidance information or position data to aircraft
(See AIR NAVIGATION FACILITY.)
NBCAP AIRSPACE- (See NATIONAL BEACON CODE ALLOCATION
NDB- (See NONDIRECTIONAL BEACON.)
NEGATIVE- "No," or "permission
not granted," or "that is not correct."
NEGATIVE CONTACT- Used by pilots to inform ATC
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
b. They were unable to contact ATC on a particular
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
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
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- Authorizes 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.
NONCOMMON ROUTE/PORTION- That segment of a North
American Route between the inland navigation facility
and a designated North American terminal.
NONCOMPOSITE SEPARATION- Separation in accordance
with minima other than the composite separation
minimum specified for the area concerned.
NONDIRECTIONAL BEACON- An L/MF or UHF radio beacon
transmitting nondirectional signals whereby the
pilot of an aircraft equipped with direction finding
equipment can determine his bearing to or from
the radio beacon and "home" on or track
to or from the station. When the radio beacon
is installed in conjunction with the Instrument
Landing System marker, it is normally called a
(See COMPASS LOCATOR.)
(See AUTOMATIC DIRECTION FINDER.)
NONMOVEMENT AREAS- Taxiways and apron (ramp) areas
not under the control of air traffic.
NONPRECISION APPROACH- (See NONPRECISION APPROACH
NONPRECISION APPROACH PROCEDURE- A standard instrument
approach procedure in which no electronic glideslope
is provided; e.g., VOR, TACAN, NDB, LOC, ASR,
LDA, or SDF approaches.
NONRADAR- Precedes other terms and generally means
without the use of radar, such as:
a. Nonradar Approach. Used to describe instrument
approaches for which course guidance on final
approach is not provided by ground-based precision
or surveillance radar. Radar vectors to the
final approach course may or may not be provided
by ATC. Examples of nonradar approaches are
VOR, NDB, TACAN, and ILS/MLS approaches.
(See FINAL APPROACH-IFR.)
(See FINAL APPROACH COURSE.)
(See RADAR APPROACH.)
(See INSTRUMENT APPROACH PROCEDURE.)
b. Nonradar Approach Control. An ATC facility
providing approach control service without the
use of radar.
(See APPROACH CONTROL FACILITY.)
(See APPROACH CONTROL SERVICE.)
c. Nonradar Arrival. An aircraft arriving at
an airport without radar service or at an airport
served by a radar facility and radar contact
has not been established or has been terminated
due to a lack of radar service to the airport.
(See RADAR ARRIVAL.)
(See RADAR SERVICE.)
d. Nonradar Route. A flight path or route over
which the pilot is performing his own navigation.
The pilot may be receiving radar separation,
radar monitoring, or other ATC services while
on a nonradar route.
(See RADAR ROUTE.)
e. Nonradar Separation. The spacing of aircraft
in accordance with established minima without
the use of radar; e.g., vertical, lateral, or
(See RADAR SEPARATION.)
(See ICAO term NONRADAR SEPARATION.)
NONRADAR SEPARATION [ICAO]- The separation used
when aircraft position information is derived
from sources other than radar.
NOPAC- (See NORTH PACIFIC.)
NORDO- (See LOST COMMUNICATIONS.)
NORMAL OPERATING ZONE (NOZ)- The NOZ is the operating
zone within which aircraft flight remains during
normal independent simultaneous parallel ILS approaches.
NORTH AMERICAN ROUTE- A numerically coded route
preplanned over existing airway and route systems
to and from specific coastal fixes serving the
North Atlantic. North American Routes consist
of the following:
a. Common Route/Portion. That segment of a North
American Route between the inland navigation
facility and the coastal fix.
b. Noncommon Route/Portion. That segment of
a North American Route between the inland navigation
facility and a designated North American terminal.
c. Inland Navigation Facility. A navigation
aid on a North American Route at which the common
route and/or the noncommon route begins or ends.
d. Coastal Fix. A navigation aid or intersection
where an aircraft transitions between the domestic
route structure and the oceanic route structure.
NORTH MARK- A beacon data block sent by the host
computer to be displayed by the ARTS on a 360
degree bearing at a locally selected radar azimuth
and distance. The North Mark is used to ensure
correct range/azimuth orientation during periods
NORTH PACIFIC- An organized route system between
the Alaskan west coast and Japan.
NOTAM- (See NOTICE TO AIRMEN.)
NOTICE TO AIRMEN- A notice containing information
(not known sufficiently in advance to publicize
by other means) concerning the establishment,
condition, or change in any component (facility,
service, or procedure of, or hazard in the National
Airspace System) the timely knowledge of which
is essential to personnel concerned with flight
a. NOTAM(D)- A NOTAM given (in addition to local
dissemination) distant dissemination beyond
the area of responsibility of the Flight Service
Station. These NOTAM's will be stored and available
b. NOTAM(L)- A NOTAM given local dissemination
by voice and other means, such as telautograph
and telephone, to satisfy local user requirements.
c. FDC NOTAM- A NOTAM regulatory in nature,
transmitted by USNOF and given system wide dissemination.
(See ICAO term NOTAM.)
NOTAM [ICAO]- A notice containing information
concerning the establishment, condition or change
in any aeronautical facility, service, procedure
or hazard, the timely knowledge of which is essential
to personnel concerned with flight operations.
a. I Distribution- Distribution by means of
b. II Distribution- Distribution by means other
NOTICES TO AIRMEN PUBLICATION- A publication issued
every 28 days, designed primarily for the pilot,
which contains current NOTAM information considered
essential to the safety of flight as well as supplemental
data to other aeronautical publications. The contraction
NTAP is used in NOTAM text.
(See NOTICE TO AIRMEN.)
NTAP- (See NOTICES TO AIRMEN PUBLICATION.)
NUMEROUS TARGETS VICINITY (LOCATION)- A traffic
advisory issued by ATC to advise pilots that targets
on the radar scope are too numerous to issue individually.
(See TRAFFIC ADVISORIES.)