CHARTSCHARTS

•Graticule - grid over the globe made up of circles

•Parallels of Latitude

•Meridians of Longitude

•Prime Meridian

•International Date Line

Meridians of LongitudeMeridians of Longitude Circles that pass directly through the Circles that pass directly through the

North and South poles (true poles)North and South poles (true poles) Meridians are measured 180 degrees Meridians are measured 180 degrees

east and west of the prime meridianeast and west of the prime meridian Prime meridian passes through Prime meridian passes through

Greenwich, EnglandGreenwich, England International Date Line is International Date Line is the meridian 180 degrees the meridian 180 degrees opposite the prime meridianopposite the prime meridian

Parallels of LatitudeParallels of Latitude Circles on the earth surface that lie Circles on the earth surface that lie

parallel to the equatorparallel to the equator The equator is the line of latitude The equator is the line of latitude

that is equidistant between the that is equidistant between the poles.poles.

Circles of latitude get smaller Circles of latitude get smaller

and smaller towards the polesand smaller towards the polesEquator = Great Circle

Small Circles

Both Longitude and Latitude are measured Both Longitude and Latitude are measured in degrees, minutes, seconds.in degrees, minutes, seconds.

(60 minutes in a degree, 60 seconds in a (60 minutes in a degree, 60 seconds in a minute)minute)

Longitude 0o to 180o East and West from prime meridian

Degrees 0

Minutes ’

Seconds ”

Meldrum Bay is at

450 55 ’ 35 ” lat

830 07 ’ 10 ” long

One nautical mile is 6080 feet, a statute mile is 5280

A nautical mile is one minute of arc along a great circle

6080 feet to 5280 feet

70 to 60

1.15 to 1

1 knot is slighter faster than 1 mph

60 knots = about 70 mph

What is located at N44˚27’30”W080˚09’30” ?What is located at N44˚27’30”W080˚09’30” ?

What is located at N42˚50’10”W081˚33’20” ?What is located at N42˚50’10”W081˚33’20” ?

What is the distance from the Equator to the What is the distance from the Equator to the North Pole?North Pole?

What is the distance between N42˚00’00” What is the distance between N42˚00’00” W081˚33’20” and N43˚50’00”W081˚33’20” ?W081˚33’20” and N43˚50’00”W081˚33’20” ?

QuestionsQuestions

Collingwood Airport

Melbourne Airport

5400 NM

110 NM

MEAN TIMEMEAN TIME Time between two transits of a meridian is Time between two transits of a meridian is

apparent solar day – variesapparent solar day – varies Mean sun travels at assumed constant Mean sun travels at assumed constant

speedspeed Mean solar day same all yearMean solar day same all year 360360oo passes in 24 hours so 24 hr = 360 passes in 24 hours so 24 hr = 360oo

1 hr = 151 hr = 15oo 1 min = 151 min = 15’ ’ 1 sec = 151 sec = 15”” Local mean time set to mid-meridian 15Local mean time set to mid-meridian 15oo

Great CirclesGreat Circles

Great circles are lines drawn directly Great circles are lines drawn directly around the Earth that will cut it into around the Earth that will cut it into two equal halves.two equal halves.

The cut would take The cut would take place directly throughplace directly through the center of the Earththe center of the Earth Great circles are the Great circles are the shortest distances betweenshortest distances between two points on the Earthtwo points on the Earth

Great Circle routeGreat Circle route

CHARTSCHARTS

•Great circle or great circle route will be a circle that cuts through the center of the globe

•Small circles – all parallels of latitude except the equator

•All meridians are great circles

ADIS ABABA

LONDON

GREENLAND

VANCOUVER

Rhumb LinesRhumb Lines

A rhumb line crosses each meridian A rhumb line crosses each meridian of longitude at the same angle.of longitude at the same angle.

Represents the path Represents the path

of constant heading of constant heading

between two points.between two points. Not the shortest Not the shortest

distance.distance.

How do we make a 2-How do we make a 2-dimensional map from a 3-dimensional map from a 3-

dimensional Earth?dimensional Earth?

Waldseemuller’s Map of Waldseemuller’s Map of 15071507

Mercator ProjectionMercator Projection Maintains constant distance between Maintains constant distance between

meridians.meridians. This causes distortionThis causes distortion

towards the poles.towards the poles. Straight line on thisStraight line on this

map is a rhumb line.map is a rhumb line.

Transverse Mercator Transverse Mercator projectionprojection

Similar to mercator, except the mapping Similar to mercator, except the mapping cylinder is rotated 90 degrees.cylinder is rotated 90 degrees.

This allows the map-maker to center the This allows the map-maker to center the projection on a meridian of longitude.projection on a meridian of longitude.

Good for small maps (VTAs) or for Good for small maps (VTAs) or for mapping a long narrow country like Chilemapping a long narrow country like Chile

Map begins toMap begins to distort once you distort once you move away frommove away from the central meridianthe central meridian

Lambert Conformal Conic Lambert Conformal Conic ProjectionProjection

Map maker fits a cone over the Earth.Map maker fits a cone over the Earth. The points where the cone is touching The points where the cone is touching

the surface of the Earth are called the the surface of the Earth are called the standard parallels.standard parallels.

Map is accurate at theMap is accurate at the standard parallels butstandard parallels but distorts as you move away.distorts as you move away. Used for medium scale Used for medium scale maps (majority of aviation maps (majority of aviation charts)charts)

Meridians of Longitude curve in Meridians of Longitude curve in towards the poles.towards the poles.

Straight lines represent great circles Straight lines represent great circles and therefore do not maintain and therefore do not maintain constant headings (unless due north-constant headings (unless due north-south)south)

Lambert Conformal Conic Lambert Conformal Conic ProjectionProjection

Great Circle/Rhumb Line on Great Circle/Rhumb Line on MercatorMercator

Great Circle/Rhumb Line onGreat Circle/Rhumb Line onLambert Conformal ConicLambert Conformal Conic

VNC 5000VNC 5000

WAC ChartWAC Chart

VTAVTA

ScaleScale

The scale used on a map depends on The scale used on a map depends on it’s use. it’s use.

Large scale (WAC charts) displays a Large scale (WAC charts) displays a large area, but not a lot of detaillarge area, but not a lot of detail

Small scale (VTA charts) displays a Small scale (VTA charts) displays a small area, and lots of detailsmall area, and lots of detail

Medium scale (VNC charts) Medium scale (VNC charts) compromise between area and scale.compromise between area and scale.

ScaleScale

Ratio of chart length to the distance Ratio of chart length to the distance on the Earth it represents.on the Earth it represents.

For example 1:500,000 means 1 inch For example 1:500,000 means 1 inch on the map equals 500,000 inches on on the map equals 500,000 inches on the ground.the ground.

*Remember* 1 minute latitude = 1 *Remember* 1 minute latitude = 1 NMNM

Magnetic VariationMagnetic Variation

The magnetic north pole does not The magnetic north pole does not coincide with the true north pole.coincide with the true north pole.

Maps are aligned with true north, Maps are aligned with true north, however our magnetic compass aligns however our magnetic compass aligns with magnetic northwith magnetic north

The difference between true north The difference between true north and magnetic north varies depending and magnetic north varies depending on your location and is called on your location and is called magnetic variation.magnetic variation.

East Magnetic VariationEast Magnetic Variation

Subtract East Variation from true Subtract East Variation from true track to get magnetic tracktrack to get magnetic track

Variation East – Magnetic LeastVariation East – Magnetic Least

West Magnetic VariationWest Magnetic Variation

Add west variation to true track to Add west variation to true track to get magnetic trackget magnetic track

Variation West – Magnetic BestVariation West – Magnetic Best

Isogonal vs. AgonalIsogonal vs. Agonal

An isogonal line is a line joining An isogonal line is a line joining points on the Earth with equal points on the Earth with equal magnetic variation.magnetic variation.

An agonal line is a line joining points An agonal line is a line joining points on the Earth with zero magnetic on the Earth with zero magnetic variationvariation

MAGNETIC DEVIATIONMAGNETIC DEVIATIONMagnetic field from airframe, engine, Magnetic field from airframe, engine,

electrical system.electrical system.Compass card shows deviation & correctionCompass card shows deviation & correction

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AGONIC LINEAGONIC LINE

CYKZ 1CYKZ 1

CYKZ 2CYKZ 2

CYKZ 3CYKZ 3

OO 1OO 1

OO 2OO 2

PQ 1PQ 1

PQ 2PQ 2

QA 2QA 2

YZ TERMINALYZ TERMINAL