Aeronautical Terms beginning with N
N1
Rotational speed of the low pressure compressor in a turbine engine.
N1,N2,N3
Spool speed expressed in percent rpm. N1 on a turboprop is the gas producer speed. N1 on a turbofan or turbojet engine is the fan speed or low pressure spool speed. N2 is the high pressure spool speed on engine with 2 spools and medium pressure spool on engines with 3 spools with N3 being the high pressure spool.
N2
Rotational speed of the high pressure compressor in a turbine engine.
N90
New York TRACON
NA
Not Authorized
Nacelle
A streamlined enclosure on an aircraft in which an engine is mounted. On multiengine propeller-driven airplanes, the nacelle is normally mounted on the leading edge of the wing.
NACG
National Aeronautical Charting Group. (obsolete)
NACO
National Aeronautical Charting Office
NAR
National Airspace Redesign
NAS
National Airspace System.
NASA
National Aeronautics and Space Administration
NASSI
National Airspace System Status Information
NAT
North Atlantic
NAT/OPS
North Atlantic Operation
NATCA
National Air Traffic Controllers Association
National Aeronautical Charting Group (NACG)
A Federal agency operating under the FAA, responsible for publishing charts such as the terminal procedures and en route charts. Moved to Aeronautical Information Services AJV-A
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 Airspace System (NAS)
Consists of a complex collection of facilities, systems, equipment, procedures, and airports operated by thousands of people to provide a safe and efficient flying environment.
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).
National defense airspace
Airspace established by a regulation prescribed, or an order issued under, 49 U.S.C. 40103(b)(3).
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.
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 operations.
National Route Program (NRP)
A set of rules and procedures 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.
National Security Area (NSA)
Areas consisting of airspace of defined vertical and lateral dimensions 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 it is necessary to provide a greater level of security and safety, flight in NSAs may be temporarily prohibited. Regulatory prohibitions are disseminated via NOTAMs.
National Transportation Safety Board (NTSB)
A United States Government independent organization responsible for investigations of accidents involving aviation, highways, waterways, pipelines, and railroads in the United States. NTSB is charged by congress to investigate every civil aviation accident in the United States.
Nautical twilight
The period of time before sunrise and after sunset when the sun is not more than 12° below the horizon.
NAV/COM
Navigation and Communication Radio.
NAVAID
Navigational Aid.
Navaid Classes
VOR, VORTAC, and TACAN aids are classed according to their operational use. The three classes of NAVAIDs 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.
NAVCEN
Coast Guard Navigation Center
Navigable airspace
Airspace at and above the minimum flight altitudes prescribed by or under this chapter, including airspace needed for safe takeoff and landing.
Navigate
To move between websites on the internet. Navigation is often accomplished by means of links or connections between sites.
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.
Navigation Specification [ICAO]
A set of aircraft and flight crew requirements needed to support performance-based navigation operations within a defined airspace. There are two kinds of navigation specifications: RNP and RNAV. Note: The Performance-based Navigation Manual (Doc 9613), Volume II contains detailed guidance on navigation specifications.
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.
Navigational Gap
A navigational course guidance gap, referred to as an MEA gap, describes a distance along an airway or route segment where a gap in navigational signal coverage exists. The navigational gap may not exceed a specific distance that varies directly with altitude.
NBCAP
National Beacon Code Allocation Plan
NBCAP AIRSPACE
National Beacon Code Allocation Plan Airspace
NCWF
National Convective Weather Forecast
ND
Navigation Displays
NDB
Nondirectional Radio Beacon.
NDB (ADF)
Nondirectional Beacon (Automatic Direction Finder).
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.
Negative Static Stability
The initial tendency of an aircraft to continue away from the original state of equilibrium after being disturbed.
Negative Torque Sensing (NTS)
A system in a turboprop engine that prevents the engine from being driven by the propeller. The NTS increases the blade angle when the propellers try to drive the engine.
Negative vorticity
Vorticity caused by anticyclonic turning; it is associated with downward motion of the air.
Net Weight
The weight of the aircraft less the weight of any chocks or other devices used to hold the aircraft on the scales.
Neutral Static Stability
The initial tendency of an aircraft to remain in a new condition after its equilibrium has been disturbed.
NEXRAD
Next Generation Weather Radar
NFDC
National Flight Data Center
NFDD
National Flight Data Digest
NFPO
National Flight Procedures Office
NGA
National Geospatial Intelligence Agency
Nickel-Cadmium Battery (NiCad)
A battery made up of alkaline secondary cells. The positive plates are nickel hydroxide, the negative plates are cadmium hydroxide, and potassium hydroxide is used as the electrolyte.
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.
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.
NIMA
National Imagery and Mapping Agency
Nimbostratus
A principal cloud type, gray colored, often dark, the appearance of which is rendered diffuse by more or less continuously falling rain or snow, which in most cases reaches the ground. It is thick enough throughout to blot out the sun.
NM
Nautical Mile.
NMAC
Near Midair Collision
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.
No Gyro Vector
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.
No procedure turn (NoPT)
Term used with the appropriate course and altitude to denote that the procedure turn is not required.
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.
No-gyro approach
A radar approach that may be used 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.
NOAA
National Oceanic and Atmospheric Administration.
Noctilucent clouds
Clouds of unknown composition which occur at great heights, probably around 75 to 90 kilometers. They resemble thin cirrus, but usually with a bluish or silverish color, although sometimes orange to red, standing out against a dark night sky. Rarely observed.
Non-Restrictive Routing (NRR)
Portions of a proposed route of flight where a user can flight plan the most advantageous flight path with no requirement to make reference to ground-based NAVAIDs.
Non-RNAV DP
A DP whose ground track is based on ground-based NAVAIDS and/or dead reckoning navigation.
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/her 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 Compass Locator.
Nondirectional Radio Beacon (NDB)
An L/MF or UHF radio beacon transmitting nondirectional signals whereby the pilot of an aircraft equipped with direction finding equipment can determine 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 ILS marker, it is normally called a compass locator.
Nonmovement Areas
Taxiways and apron (ramp) areas not under the control of air traffic.
Nonprecision approach
A standard instrument approach procedure in which only horizontal guidance is provided.
Nonprecision approach procedure
A standard instrument approach procedure in which no electronic glide slope is provided.
Nonprecision Approach Runway
An instrument runway served by visual aids and a nonvisual aid providing at least directional guidance adequate for a straight-in approach.
Nonradar
Precedes other terms and generally means without the use of radar, such as: Nonradar Approach, Nonradar Approach Control, Nonradar Arrival, Nonradar Route, and Nonradar Separation.
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.
Nonradar Approach Control
An ATC facility providing approach control service without the use of radar.
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.
Nonradar Route
A flight path or route over which the pilot is performing his/her own navigation. The pilot may be receiving radar separation, radar monitoring, or other ATC services while on a nonradar route.
Nonradar Separation
The spacing of aircraft in accordance with established minima without the use of radar; e.g., vertical, lateral, or longitudinal separation.
Nonradar Separation [ICAO]
The separation used when aircraft position information is derived from sources other than radar.
NOPAC
North Pacific
NoPT
No Procedure Turn.
NORDO
(No Radio) Aircraft That Cannot Or Do Not Communicate By Radio When Radio Communication Is Required Are Referred To As “Nordo.
Norm-referenced testing
System of testing in which students are ranked against the performance of other students.
Normal
In meteorology, the value of an element averaged for a given location over a period of years and recognized as a standard.
Normal Category
An airplane that has a seating configuration, excluding pilot seats, of nine or less, a maximum certificated takeoff weight of 12,500 pounds or less, and intended for non-acrobatic operation.
Normal Operating Zone (NOZ)
The NOZ is the operating zone within which aircraft flight remains during normal independent simultaneous parallel ILS approaches.
Normal refraction
Refraction of the radar beam under normal atmospheric conditions; normal radius of curvature of the beam is about 4 times the radius of curvature of the Earth.
Normalizing (Turbonormalizing)
A turbocharger that maintains sea level pressure in the induction manifold at altitude.
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 American 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.
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 of CENRAP.
North Pacific
An organized route system between the Alaskan west coast and Japan.
NOTAM
Notice To Airmen
NOTAM L
Local 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 Telecommunication. B. II Distribution-Distribution By Means Other Than Telecommunications
NOTAM(D)
A NOTAM Given (In Addition To Local Dissemination) Distant Dissemination Beyond The Area Of Responsibility Of The Flight Service Station. These NOTAMs Will Be Stored And Available Until Canceled
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 operations. There are two types: NOTAM(D) and FDC NOTAM.
Notice to Airmen (NOTAM)
A notice filed with an aviation authority to alert aircraft pilots of any hazards en route or at a specific location. The authority in turn provides means of disseminating relevant NOTAMs to pilots.
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.
NOZ
Normal Operating Zone
NPA
Nonprecision Approach
NPRM
Notice of Proposed Rulemaking
NRP
National Route Program.
NRR
Non-Restrictive Routing
NRS
National Reference System
NSA
National Security Area.
NSE
Navigation System Error
NSW
No Significant Weather
NTAP
Notice To Airmen Publication
NTSB
National Transportation Safety Board.
NTZ
No Transgression Zone
Nuisance Alert
An alert in which one or more of the following is true: 1. The alert is generated by a known situation that is not considered an unsafe operation, such as LAHSO or other approved operations. 2. The alert is generated by inaccurate secondary radar data received by the Safety Logic System. 3. One or more of the aircraft involved in the alert is not intending to use a runway (for example, helicopter, pipeline patrol, non-Mode C overflight, etc.).
Numerical forecasting
Forecasting by digital computers solving mathematical equations; used extensively in weather services throughout the world.
Numerical weather prediction
Forecasting by digital computers solving mathematical equations; used extensively in weather services throughout the world.
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.
NWS
National Weather Service.
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