Glossary of Aviation Terminology

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Nacelle: An enclosure on an aircraft.

Nap-of-the-earth flight: Flight with a goal to remain close to the earth, usually below the height of surrounding trees and less than 100 ft above the terrain; Compare: terrain following

Natural frequency: Standard engineering term See Also: second-order filter; Symbols: omega sub n; Typical Units: rad/s,Hz; Dimensions: 1/Time;

Navigation: A system, usually software, in which the primary purpose is to generate position relative to a coordinate frame, usually fixed earth frame, such as latitude and longitude or UTM;

Navigation aid: A device or process to help with navigation, such as a VOR station or a position update;

Navigation reference point (NRP): A point, usually fixed in earth coordinates but possibly moving; Also, a basic guidance mode, providing lateral guidance to an NRP, either by course or by direct (operator selectable); Synonyms: point;

Noise: Part of received data that is undesired, consisting of random sinusoidal terms added to a signal; Compare: offset, signal;

Normalizer: Function to restrict input to a specific range, such as restricting an angle alpha in radians so that -pi le alpha le +pi; angles usually require normalizing following any computation; normalized variables often present problems for filters and other functions at their discontinuities;

NRP: Navigation reference point

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