Browse the glossary using this index

Special | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | ALL

Page:  1  2  (Next)
  ALL

N

Navigation specification

Navigation specification. 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:
Required navigation performance (RNP) specification. A navigation specification based on area navigation that includes
the requirement for performance monitoring and alerting, designated by the prefix RNP, e.g. RNP 4, RNP APCH.
Area navigation (RNAV) specification. A navigation specification based on area navigation that does not include the
requirement for performance monitoring and alerting, designated by the prefix RNAV, e.g. RNAV 5, RNAV 1.


Note.— The Performance-based Navigation (PBN) Manual (Doc 9613), Volume II, contains detailed guidance on
navigation specifications.


Near-parallel runways

Near-parallel runways. Non-intersecting runways whose extended centre lines have an angle of convergence/divergence of 15
degrees or less.


Newton

Newton (N). The force which when applied to a body having a mass of 1 kilogram gives it an acceleration of 1 metre per
second squared.


NEXRAD

NEXRAD or Nexrad (Next-Generation Radar) is a network of 159 high-resolution S-band Doppler weather radars operated by the National Weather Service (NWS), an agency of the National Oceanic and Atmospheric Administration (NOAA) within the United States Department of Commerce, the Federal Aviation Administration(FAA) within the Department of Transportation, and the U.S. Air Force within the Department of Defense. It's technical name is WSR-88D, which stands for Weather Surveillance Radar, 1988, Doppler.

NEXRAD detects precipitation and atmospheric movement or wind. It returns data which when processed can be displayed in a mosaic map which shows patterns of precipitation and its movement. The radar system operates in two basic modes, selectable by the operator – a slow-scanning clear-air mode for analyzing air movements when there is little or no activity in the area, and a precipitation mode, with a faster scan for tracking active weather. NEXRAD has an increased emphasis on automation, including the use of algorithms and automated volume scans.


Night

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 prescribed by the appropriate authority.
Note.— Civil twilight ends in the evening when the centre of the sun’s disc is 6 degrees below the horizon and begins in the
morning when the centre of the sun’s disc is 6 degrees below the horizon.


Night-Ireland

“night” means 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. In or over the State, “night” shall be deemed to be, during the
period beginning on the 1st day of April, and ending on the 30th day of September, the
time between half an hour after sunset and half an hour before sunrise, and during the
remainder of the year, the time between sunset and sunrise, and for the purpose of this
definition sunset shall be determined at surface level.


NM

Nautical mile (NM). The length equal to 1 852 metres exactly.


Non-instrument runway

Non-instrument runway. A runway intended for the operation of aircraft using visual approach procedures.


Normal operating differential pressure

‘Normal operating differential pressure’ means the pressure differential between the cabin
pressure and the outside ambient pressure, including the tolerances of the normal pressure regulating
system.


NOSIG

The trend forecast shall indicate significant changes in respect of one or more of the elements: surface wind, visibility,
weather and clouds. Only those elements shall be included for which a significant change is expected. However, in the case
of significant changes in respect of cloud, all cloud groups, including layers or masses not expected to change, shall be
indicated. In the case of a significant change in visibility, the phenomenon causing the reduction of visibility shall also be
indicated. When no change is expected to occur, this shall be indicated by the term “NOSIG”.

NOTE : Refer to ICAO Annex 3, 2.2 - 2.2.7



Page:  1  2  (Next)
  ALL