Route Selection Route Selection and Navigationand Navigation

Chapter 7

Direction Direction DeterminationDetermination

NorthNorth

True NorthTrue North- line - line through North Pole.through North Pole.

Magnetic NorthMagnetic North- - direction to northern direction to northern magnetic pole.magnetic pole.

Grid NorthGrid North-North as -North as established by map established by map maker.maker.

TrueNorth

MagneticNorth

GridNorth

By Sighting Polaris, a Star located almost over North Pole. By Sighting Polaris, a Star located almost over North Pole. Northerly direction along a line of longitudeNortherly direction along a line of longitude

A A gyrocompassgyrocompass is a compass finds North by using an fast is a compass finds North by using an fast spinning wheel and friction forces in order to exploit the spinning wheel and friction forces in order to exploit the rotation of the Earth. rotation of the Earth.

Find true North, i.e. the direction of Earth's rotational Find true North, i.e. the direction of Earth's rotational axis, as opposed to magnetic Northaxis, as opposed to magnetic North

Not affected by metalNot affected by metal

True NorthTrue North

Magnetic NorthMagnetic North North Arrow of Magnetic compass align North-South with North Arrow of Magnetic compass align North-South with

earth’s magnetic line of force.earth’s magnetic line of force. North magnetic pole currently located in Northern Canada North magnetic pole currently located in Northern Canada

(1227 Km from Geographical pole i.e. Pole of Rotation)(1227 Km from Geographical pole i.e. Pole of Rotation) Compass: Determines direction using a magnetic north Compass: Determines direction using a magnetic north

needle pivoting 360 degrees and pointing to magnetic northneedle pivoting 360 degrees and pointing to magnetic north

Magnetic NorthMagnetic North

Isogonics chartIsogonics chart

http://www.centennialofflight.gov/essay/Dictionary/Poles/DI81.htm

The Agonic Line is the line of zero degree variation

Declination angleDeclination angle

Magnetic declinationMagnetic declination

The angular The angular distance between distance between north and magnetic north and magnetic northnorth

Degree of Degree of declination depends declination depends on geographic on geographic location location

True and magnetic True and magnetic north are the same north are the same at Agonic lineat Agonic line

MAGNETIC NORTH

TRUE NORTH

GRID NORTH

Grid NorthGrid North

The direction of a grid line which is The direction of a grid line which is parallel to the central meridian on a parallel to the central meridian on a map. map.

Grid North may not match true north Grid North may not match true north because a map is a flat representation of because a map is a flat representation of a curved surface. a curved surface.

Grid North pertains to the north for a Grid North pertains to the north for a specific plane coordinate system. All specific plane coordinate system. All north-south lines run parallel to one north-south lines run parallel to one another in the UTM projections.another in the UTM projections.

Types of compassTypes of compass

Azimuth: 0 to 360 degrees, bearingsAzimuth: 0 to 360 degrees, bearings Read in clockwise direction from northRead in clockwise direction from north

Quadrant: 0 to 90 degrees, bearingsQuadrant: 0 to 90 degrees, bearings read eastward or westward of the north or read eastward or westward of the north or

south directionsouth direction Mariner’s compass: 32 bearingsMariner’s compass: 32 bearings

Also called a compass roseAlso called a compass rose Converting exerciseConverting exercise

Direction Direction DesignationDesignation

Types of AzimuthTypes of Azimuth An azimuth is an angle measured clockwise from a An azimuth is an angle measured clockwise from a

base line direction (north).base line direction (north). Defined as a horizontal angle measured clockwise Defined as a horizontal angle measured clockwise

from a baselinefrom a baseline Types of azimuth:Types of azimuth:

Orthodrome based on true north Orthodrome based on true north magnetic azimuths based on magnetic north magnetic azimuths based on magnetic north grid azimuths measures with grid north as basegrid azimuths measures with grid north as base

Bearing: Same as a azimuth but representedBearing: Same as a azimuth but representedusing North or south as a baselineusing North or south as a baseline

Back bearing: the 180-degree opposite of the Back bearing: the 180-degree opposite of the azimuth or bearing. Also known as back azimuth.azimuth or bearing. Also known as back azimuth.

Azimuths (cont.)Azimuths (cont.)

546000mE

38 1

8000

mN

19

20

22

21

23

47 48 49 50 51 52 53 54

GNGN

Grid azimuth = Grid azimuth = 45 degrees45 degrees

OrthodromeOrthodrome

A great circles arc that is A great circles arc that is casted between two casted between two points on a surface of a points on a surface of a sphere. Is the shortest sphere. Is the shortest geodetic connecting line geodetic connecting line between two points on a between two points on a sphere.sphere.

Measuring an AzimuthMeasuring an AzimuthProtractorsProtractors

Measuring an AzimuthMeasuring an AzimuthCompassesCompasses

302010

W

E

E. decl.

W.decl.

mm

BASE PLATE

DIRECTION OFTRAVEL ARROW

BASE LINE

INDEX LINE

ORIENTEERINGARROW

ROTATINGDIAL

FLOATINGMAGNETIC

NEEDLE

ORIENTEERINGLINE

N

S

11

/ 21

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Magnetic Lensatic Compass(Military Type)

Silva Polaris Compass(Civilian Orienteering)

Direction - Some Direction - Some ExamplesExamples

Where is north onthis map?

Where is north onthis map?

Position Position DeterminationDetermination

• Land OperationLand Operation Water Operation Water Operation

Resection methodResection method

Resection is the method of locating Resection is the method of locating one's position on a map by one's position on a map by determining the grid azimuth to at determining the grid azimuth to at least two well-defined locations that least two well-defined locations that can be pinpointed on the map. can be pinpointed on the map.

For greater accuracy, the desired For greater accuracy, the desired method of resection would be to use method of resection would be to use three or more well-defined locations.three or more well-defined locations.

http://www.map-reading.com/resect.php

Nautical ChartsNautical Charts Used for marine navigation and contain information Used for marine navigation and contain information

on all navigational aids, such as buoys and beacons, on all navigational aids, such as buoys and beacons, lighthouses, radio and radar stations, shipping lighthouses, radio and radar stations, shipping channels, restricted areas. channels, restricted areas.

Types of nautical charts: Types of nautical charts: Sailing chartsSailing charts are used to fix a position in long-distance are used to fix a position in long-distance

navigation. They usually employ Mercator's projection. navigation. They usually employ Mercator's projection. General chartsGeneral charts of the coast are used the same as sailing of the coast are used the same as sailing

charts and also for near-shore navigation. They employ charts and also for near-shore navigation. They employ Mercator's projection. Mercator's projection.

Coast chartsCoast charts are used for coastwide navigation and to are used for coastwide navigation and to approach a shore from a long distance offshore. They show approach a shore from a long distance offshore. They show details of land formations and artificial landmarks which details of land formations and artificial landmarks which help fix positions. help fix positions.

Harbor chartsHarbor charts are used to navigate harbors and their are used to navigate harbors and their approaches. They greatly detail terrain and artificial approaches. They greatly detail terrain and artificial objects.objects.Buoys - floating objects that are anchored to the bottom. Beacons -Which are structures that are permanently fixed to the sea-bed or land.

http://www.boatus.org/onlinecourse/ReviewPages/BoatUSF/Project/info5d.htm

Nautical ChartsNautical Charts

Symbols used in Nautical Symbols used in Nautical ChartsCharts

Position DeterminationPosition Determination Lines of Position:Lines of Position: The modern chart shows us The modern chart shows us

positions of many recognizable navigation aids positions of many recognizable navigation aids like churches and lighthouses, which facilitate like churches and lighthouses, which facilitate the approach to a coastal area.the approach to a coastal area.

Ranges:Ranges: A precise way to obtain a Line of A precise way to obtain a Line of Position (and without a compass) is to locate Position (and without a compass) is to locate two navigational aids in line. two navigational aids in line.

Position DeterminationPosition Determination

FixFix is the ship's position on the earth at is the ship's position on the earth at some given point in time. A fix is some given point in time. A fix is determined by the simultaneous determined by the simultaneous intersection of Line of Positions.intersection of Line of Positions.

Dead reckoning Dead reckoning is a technique to is a technique to determine a ship's approximate position determine a ship's approximate position by applying to the established charted by applying to the established charted position a vector or series of vectors position a vector or series of vectors representing true courses and speed.representing true courses and speed.

LORAN (LOng RAnge LORAN (LOng RAnge Navigation)Navigation)

LORAN is a position-fixing system consisting of LORAN is a position-fixing system consisting of an array of fixed stations that transmit precisely an array of fixed stations that transmit precisely synchronized signals to mobile receivers.synchronized signals to mobile receivers.

Fixed difference in the time of arrival of the Fixed difference in the time of arrival of the signals from any two stations will define a signals from any two stations will define a hyperbolic arc on which the receiver must lie.hyperbolic arc on which the receiver must lie.

Global Positioning Global Positioning SystemSystem

The Global Positioning System (GPS) The Global Positioning System (GPS) consists of a constellation of satellites that consists of a constellation of satellites that broadcast two pieces of data to radio-broadcast two pieces of data to radio-navigation receivers. A receiver determine navigation receivers. A receiver determine the precisely-known position of these the precisely-known position of these satellites at the same time, then the satellites at the same time, then the receiver could precisely determine its own receiver could precisely determine its own position through position through triangulationtriangulation..

Aeronautical chartsAeronautical charts Contain a great deal of data on ground features, with an Contain a great deal of data on ground features, with an

emphasis on such things as landmarks, elevations, emphasis on such things as landmarks, elevations, heights of obstructions, airports, and airways.heights of obstructions, airports, and airways.

World Aeronautical Charts World Aeronautical Charts (WAC) based on Lambert (WAC) based on Lambert Conformal Conic projection are used for flight planning Conformal Conic projection are used for flight planning and in-flight navigation by VFR pilots on extended cross and in-flight navigation by VFR pilots on extended cross country flight at low to medium altitudes and medium to country flight at low to medium altitudes and medium to high airspeed.high airspeed.

Sectional Aeronautical Charts: Sectional Aeronautical Charts: Series of charts based Series of charts based on Lambert Conformal Conic projection covering the on Lambert Conformal Conic projection covering the United States at a scale of 1:500,000. United States at a scale of 1:500,000. The topographic information The topographic information consists of contour lines, consists of contour lines, shaded relief, drainage patterns, and an extensive shaded relief, drainage patterns, and an extensive selection of visual checkpoints and landmarks. selection of visual checkpoints and landmarks. Cultural features Cultural features include cities and towns, roads, include cities and towns, roads, railroads, and other distinct landmarks. railroads, and other distinct landmarks. The The aeronautical information aeronautical information includes visual and radio includes visual and radio aids to navigation, airports, controlled airspace, special-aids to navigation, airports, controlled airspace, special-use airspace, obstructions, and related data.use airspace, obstructions, and related data.

Aeronautical chartsAeronautical charts

World Aeronautical World Aeronautical Charts Charts

Sectional Aeronautical Sectional Aeronautical Chart Chart

Terminal Area ChartsTerminal Area Charts

Helicopter Route Charts Helicopter Route Charts