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Article

Almanac

A book that contains astronomical or meteorological data arranged according to days, weeks, and months of a given year and may also include diverse information of a nonastronomical character. This article is restricted to astronomical and…

Article

Altimeter

Any device which measures the height of an aircraft. The two chief types are the pressure altimeter, which measures the aircraft's distance above sea level, and the radar altimeter, which measures distance above the ground. Pressure Altimeter A…

Biography

Berthoud, Ferdinand (1727–1807)

Article

Buoy

An anchored or moored floating object, other than a lightship, intended as an aid to navigation. Buoys are the most numerous of all engineered aids to navigation, with some 20,000 in United States waters alone.A great variety of buoys are in use.…

Biography

Cook, James (1728–1779)

Biography

Harrison, John (1693–1776)

Biography

Lacaille, Nicolas Louis de (1713–1762)

Biography

Lesseps, Ferdinand Marie (1805–1894)

Biography

Maskelyne, Nevil (1732–1811)

Biography

Maury, Matthew Fontaine (1806–1873)

Biography

Mayer, Johann Tobias (1723–1762)

Biography

Ptolemy, (Claudius Ptolemaeus) (lived AD 2nd century)

An article from Science News May 2018

This AI uses the same kind of brain wiring as mammals to navigate

Briefing

Progress in developing x-ray pulsar-based navigation (XNAV) Published in 2018

In early 2018, NASA announced that it had demonstrated a new type of celestial navigation for the first time. Called XNAV, for x-ray pulsar-based navigation, it relies on beams of radiation from pulsars—the cinders of exploded, massive stars. As…

Briefing

Sea turtle navigation Published in 2015

One of the most remarkable features of the sea (marine) turtles that inhabit the tropical and subtropical waters of the world is their homing ability. Throughout the year, sea turtles swim huge distances, often more than 1600 kilometers (1000…

Article

Air navigation

A discipline that combines the means to know the location and heading of an aircraft with respect to some map or coordinate system, with guidance which means steering the aircraft along some desired path toward a destination. The construction of…

Article

Air-traffic control

A service to promote the safe, orderly, and expeditious flow of air traffic. Safety is principally a matter of preventing collisions with other aircraft, obstructions, and the ground; assisting aircraft in avoiding hazardous weather; assuring that…

Article

Aircraft collision avoidance system

A device that reduces the risk of midair collision by providing advisories to the flight crew. It is known in the United States as a Traffic Alert and Collision Avoidance System (TCAS), and operates independently of the ground-based air-traffic…

Article

Aircraft compass system

An instrument that indicates the bearing, or angle of the direction in which an aircraft is pointing in the horizontal plane. A compass may indicate magnetic heading or bearing, bearing referenced to a radio signal source, or bearing with respect to…

Article

Aircraft instrumentation

A coordinated group of instruments that provides the flight crew with information about the aircraft and its subsystems. Together with the controls, aircraft instruments form the human–machine interfaces that enable the flight crew to operate the…

Article

Airport surface detection equipment

A ground mapping system that uses analog radar equipment to provide surveillance of aircraft and other surface vehicles on an airport surface. It is used by air-traffic controllers in airport control towers to monitor and control the movement of…

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Airspeed indicator

A device that computes and displays speed of an aircraft relative to the air mass in which the aircraft is flying. Three common types are the indicated airspeed meter, true airspeed indicator, and Machmeter.The commonest type is the indicated…

Article

Alternative satellite navigation systems

The satellite navigation systems GPS (the U.S.–managed Global Positioning System) and GLONASS (the Russian global navigation satellite system) have been operational in some form for decades. Other global and regional navigational satellite systems…

Article

Automatic horizon

A device that provides the pilot with symbols representative of the attitude of an aircraft relative to an artificial horizon. In an automatic or artificial horizon a vertical gyro moves a horizon bar relative to a fixed aircraft index. Motion of…

Article

Automatic landing system

The means for guiding and controlling aircraft from an initial approach altitude to a point where safe contact is made with the landing surface. Such systems differ from low-approach systems in three major respects: (1) They furnish not only…

Article

Autopilot

An automatic means for steering an aircraft, ship, or other vehicle. The terminology means to automatically (autonomously) control a mode of the vehicle, usually its trajectory. Examples include altitude, speed, heading, accelerations, body rates,…

Article

Celestial navigation

Navigation with the aid of celestial bodies, primarily for determination of position when landmarks are not available. In celestial navigation, position is not determined relative to the objects observed, as in navigation by piloting, but in…

Article

Dead reckoning

A form of navigation that determines position of a craft by advancing a previous position to a new one on the basis of assumed distance and direction moved. The name probably stems from the early practice of determining speed by throwing overboard a…

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Direction-finding equipment

Equipment used for determining the direction from which a received signal is being radiated. Direction finders serve a variety of applications. Direction finders can be used for navigation purposes to determine the heading of a vehicle relative to a…

Article

Distance-measuring equipment

An internationally standardized navigation system which allows an aircraft to measure its distance from a selected ground-based beacon. Such beacons are used throughout the world by all airliners, most of the military aircraft of the West, and a…

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Doppler VOR

A very high-frequency omnidirectional radio range (VOR) employing the Doppler principle. The bearing accuracy achieved by users when VOR beacons are installed in the vicinity of obstructions, or when aircraft using VOR signals fly over mountainous…

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Electronic navigation systems

Systems that locate suitably equipped users by means of measurements made by electronic sensors. Typical measurements include distance or bearing from a vehicle to a known point, or direct determination of the present position of the vehicle in a…

Article

Glide-path indicator

An aircraft landing instrument that provides the pilot with a visual indication of vertical and horizontal angular deviations from a glide path or final approach segment (FAS) that indicates the off-center position of the aircraft from the FAS with…

Article

Ground proximity warning system

A system carried on many aircraft to warn the pilot that the aircraft may be in danger of inadvertent contact with the ground. It is intended to reduce the occurrence of controlled-flight-into-terrain (CFIT) accidents, in which aircraft with no…

Article

Guidance systems

The algorithms, computers, and sensors used to produce steering commands in the control of mobile platforms. The types of vehicles include airplanes, rockets, missiles, ships, torpedoes, drones, and others, including robotic vehicles used in…

Article

Gyrocompass

A north-seeking form of gyroscope used as a directional reference in navigation. The first practical gyrocompasses were developed by H. Anschütz (Germany) in 1908, E. A. Sperry (United States) in 1911, and S. G. Brown (England) in 1916. Modern…

Article

Gyroscope

A device that is used to define a fixed direction in space or to determine the change in angle or the angular rate of its carrying vehicle with respect to a reference frame. Gyroscopes (also called gyros) respond to vehicle angular rates, that is,…

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Homing

A process of navigation by which a destination is approached by keeping some navigation parameter constant. In its early uses, the most commonly chosen parameter was the relative bearing from the vehicle to destination as determined from a signal…

Article

Hyperbolic navigation system

A navigation system that produces hyperbolic lines or surfaces of position by measuring the difference in times of reception (or phase difference) between radio signals from two or more synchronized transmitters. Such systems require the use of a…

Article

Inertial navigation system

A self-contained system that can automatically determine the position, velocity, and attitude of a moving vehicle for the purpose of directing its future course. Based on prior knowledge of time, gravitational field, initial position, initial…

Article

Instrument landing system (ILS)

A collection of discrete radio navigation aids used by pilots of all types of aircraft for approach guidance to a specific airport runway, especially during times of limited visibility. Typically, three components constitute the instrument landing…

Article

Lighthouse

A distinctive structure, built on or near a shore, which exhibits a light of distinctive characteristics to serve as an aid to navigation (see illustration). Lesser lights may be displayed from fixed structures called beacons or from floating buoys…

Article

Loran

A navigation system from which hyperbolic lines of position are determined by measuring the difference in times of arrival of pulses from widely spaced, synchronized transmitting stations. Since radio waves travel at the speed of light, a line of…

Article

Magnetic compass

A compass depending for its directive force upon the attraction of the Earth's magnetism on a magnet free to turn in any horizontal direction. A compass is an instrument used for determining horizontal direction. Principle of operation The magnetic…

Article

Marine navigation

The process of directing a watercraft to a destination in a safe and expeditious manner. From a known present position, a course is determined that avoids dangers, and on this course estimates are made of time schedules. The task is to make…

Article

Microwave landing system (MLS)

An all-weather aircraft landing-guidance system that operates at microwave frequencies and provides deviations from the landing runway centerline using a time-referenced scanning beam (TRSB) technique. The MLS was standardized in 1988 and approved…

Article

Navigation

The process of directing the movement of a craft from one place to another. Navigation involves position, direction, distance, time, and speed.The process of keeping track of a craft's location by measuring and applying progress from a previous…

Article

Piloting

The form of navigation in which position is determined relative to external reference points, usually fixed points on the Earth. It is the oldest form of navigation. The following remarks are formulated in the context of marine navigation. However,…

Article

Polar navigation

The complex of navigational techniques modified from those used in other areas to suit the distinctive regional character of polar areas. Although polar navigation has become routine to a rising number of navigators operating in and through such…

Article

Precision approach radar (PAR)

A tracking system that provides a ground control approach (GCA) air-traffic controller with a precise display of an aircraft's position relative to a runway final-approach course. To ensure absolute safety, precise information is displayed on a plan…

Article

Radio compass

A popular term for an automatic radio direction finder used for navigation purposes on ships and aircraft. It is not strictly a compass, because it indicates direction with respect to the radio station to which it is tuned, rather than to the north…

Article

Rate-of-climb indicator

An aircraft instrument that provides an indication of the vertical change of the aircraft position within the air mass. It is more commonly known as the vertical-velocity or vertical-speed indicator. Contained within a sealed case, it is connected…

Article

Rho-theta system

A navigation system in which one or more signals are emitted from a facility (or colocated facilities) to produce simultaneous indication of bearing and distance. Since a bearing is a radial line of position and a distance is a circular line of…

Article

Satellite navigation systems

Radionavigation systems using artificial satellites as sources of radio signals and position references. Development of satellite-based systems for positioning and navigation began almost immediately after the launch of Sputnik I by the Soviet…

Article

Schuler pendulum

Any apparatus which swings, because of gravity, with a natural period of 84.4 min, that is, with the same period as a hypothetical simple pendulum whose length is the Earth's radius. In 1923 Max Schuler showed that such an apparatus has the unique…

Article

Sextant

A navigation instrument used for measuring angles, primarily altitudes of celestial bodies. Originally, the sextant had an arc of 60°, or one-sixth of a circle, from which the instrument derived its name. Because of the double-reflecting principle…

Article

Ship routing

The selection of the most favorable route for a ship's transit in the open ocean. Safety, economics, and environmental protection play a key role in determining this selection. In the late 1890s, the practice of following predetermined routes for…

Article

Space navigation and guidance

The determination of the position and velocity of a space probe with respect to a target body or a known reference body such as the Earth (navigation) and, based upon this determination, the application of propulsive maneuvers to alter the…

Article

Stall-warning indicator

A device that determines the critical angle of attack for a given aircraft, at which point the lift stops increasing and the aircraft will no longer sustain itself in steady-state condition (level flight or climb/descent). The indicator usually…

Article

Star tracker

A device that automatically measures the angular separation of stellar observations with respect to a reference platform. It is also referred to as an astrotracker.By utilizing the star tracker in conjunction with a precise time reference…

Article

Surveillance radar

Any radar equipment used by civil or military authorities for locating aircraft, ships, or ground vehicles; most commonly, in civil air-traffic management, a radar used by controllers to indicate the position of aircraft aloft or on the airport…

Article

Tacan

A member of the rho-theta family of air navigation systems which define an aircraft's position by its distance and bearing to a single beacon. Such systems inherently answer the navigator's questions of “in what direction” and “how far,” without…

Article

Turn and bank indicator

A combination instrument which provides an aircraft pilot with two distinct pieces of information: the aircraft's rate of turn about the vertical axis, and the relationship between this rate and the aircraft's angle of bank. It is also known as the…

Article

Underwater navigation

The process of directing the movements of submersible vehicles, and divers, from one point to another. The development of improved submersible vehicles, coupled with advances in saturated diving, has resulted in new requirements for underwater…

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Vessel traffic service

A marine traffic management system, operated by a competent authority, for improving the safety and efficiency of vessel traffic and protecting the environment within designated service areas. A vessel traffic service (VTS) has the ability and the…

Article

VOR (VHF omnidirectional range)

A short-range air navigation aid, which provides azimuth aid by visual means of cockpit instruments. A VOR system provides properly equipped aircraft with bearing information relative to the VOR station and magnetic north. The VOR system is used…

Article

Yaw indicator

An aircraft instrument that provides a measure of the sideslip or yaw of the aircraft, defined as the angular measure of the relative wind in relation to a vertical plane passing through the longitudinal center of the aircraft. This device is not…

Article

Indoor navigation for first responders

On December 3, 1999, a tragedy occurred in Worcester, Massachusetts, at a fire in a large aging brick warehouse, the former Worcester Cold Storage and Warehouse Co. building. What at first seemed like a routine response situation by the Worcester…

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Time transfer using a satellite navigation system

Several satellite navigation systems are currently in operation or are scheduled for deployment in the near future. These include the United States Global Positioning System (GPS), the Russian Global Navigation Satellite System (GLONASS) satellites,…

Article

Coordinated Universal Time (UTC) scale

The precise measurement of time and time interval is a key enabler of modern technology in which a profusion of electronic devices and communications equipments depend on the synchronization of time and frequency in order to operate properly over…

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Pulsar navigation

Throughout history, celestial sources have been utilized for vehicle navigation. Great ships have successfully sailed Earth's oceans utilizing only these celestial aides. Many vehicles operating in the space environment also navigate utilizing…

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Animal navigation

Animals possess a remarkable ability to navigate underwater, on land, and in the air. The distances navigated range from the immediate vicinity of their homes to migration over thousands of kilometers. Animal navigational abilities have been known…

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Assisted GPS and location-based services

As recently as 2004, the Global Positioning System (GPS) receiver most widely used by the U.S. military was the PLGR (Precision Lightweight GPS Receiver). It is a five-channel receiver that operates on only one of the three GPS frequencies (L1), has…

Article

Atom interferometer, magnetic waveguide

A magnetic waveguide atom interferometer is a device which creates an interference pattern by coherently splitting a Bose-Einstein condensate (BEC) into two separate parts, guiding each along separate paths using magnetic waveguides, and recombining…

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Autonomous navigation

Autonomous navigation means that a vehicle is able to plan its path and execute its plan without human intervention. In some cases remote navigation aids are used in the planning process, while at other times the only information available to…

Article

Balloon circumnavigation

The first crewless circumnavigation of the globe was achieved by one of the 280 balloons flown around the Southern Hemisphere by the U.S. National Center for Atmospheric Research (NCAR) during 1966 as part of its GHOST project. Many of the…

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Galileo Navigation Satellite System

The Galileo program is a European-sponsored satellite navigation program that is to provide worldwide navigation and time services to a large variety of transportation, telecommunication, scientific, recreational, and other applications. Although…

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Global Positioning System (GPS)

The Global Positioning System is a satellite-based system providing worldwide continuous position, velocity, time, and related data to civil and military users. It has a growing number of applications in the fields of marine, land, and aerospace…

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Integrity monitoring (satellite navigation)

Satellite navigation systems provide a number of significant benefits over traditional ground-based navigation aids. These benefits include global coverage, improved accuracy, and the ability to support area navigation (the ability to navigate along…

Article

International GPS Service

The Global Positioning System (GPS) provides unprecedented potential for precise ground- and space-based positioning, timing, and navigation anywhere in the world. Extremely precise use of GPS, particularly for earth sciences applications, stems…

Article

Location-based security

In numerous applications it is desirable to restrict access to plaintext data based on the recipient's location or the time. For instance, in digital cinema distribution, the distributor would like to restrict access to the location of the…

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Satellite navigation advances

The Global Positioning System (GPS) has revolutionized navigation and precise timing applications for countless military and civilian users worldwide. Businesses, and indeed entire industries worldwide, have been created using the position and…

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Satellite-based geodesy

The classical definition of geodesy is the “science of the measurement and mapping of the Earth's surface” by direct measurements, such as terrestrial triangulation, leveling, and gravimetric observations, and, in the past 50 years, also with space…

Article

Wide-Area Augmentation System (WAAS)

The Global Positioning System (GPS) is used in a wide variety of both civil and military applications. These applications affect users in everyday activities, from communications and power generation to precisely determining one's location. The GPS…

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from article Automatic landing system

Schematic of radar-beam system for aircraft-carrier and shore applications.

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from article Altimeter

Schematic arrangement of sensitive pressure altimeter. 1 ft = 0.3 m.

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from article Altimeter

Radar altimeter principles. (a) Ideal return power distribution, which would be observed if the signal came only from the closest point to the radar. (b) Typical distribution of average returned power as a function of distance from the radar. (c)…

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from article Altimeter

Block diagrams of typical radar altimeters. (a) Automatic pulse altimeter. Control, tracking, and output circuits may all be digital. (b) Servo-adjusted-sweep FM altimeter.

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from article Sextant

Marine sextant.

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from article Sextant

Periscopic sextant for use in aircraft.

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from article Air-traffic control

Terminal radar controller's plan view display. Aircraft positions are shown by radar returns. Display is centered on primary airport with parallel and intersecting runways. Range rings are spaced 5 mi (9 km) apart. Airspace within boundary and above…

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from article Hyperbolic navigation system

Typical grid of hyperbolic lines of position formed by a master (M) and two secondary stations (W and X).

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from article Hyperbolic navigation system

Individual lines of position from a master and two secondaries at location P. γ =LOP crossing angle.

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from article Hyperbolic navigation system

Typical curves of constant horizontal dilution of precision (HDOP) for a master (X) and two secondary stations (X and Y). Numbers give HDOP values of contours.

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from article Schuler pendulum