1、Maps and ChartsNAVIGATIONThe earth is a sphere and therefore its surface cant be represented on a flat planeWe need a map to show the topography with little distortionThere are two principal types of chart projections used in air navigation charts, the Transverse Mercator and the Lambert Conformal C

2、onicEach have their own advantages and are both usedOUTLINEMercator ProjectionTransverse Mercator ProjectionLambert Conformal Conic ProjectionTopographical Symbols / Elevation and Contours (Relief)Scale and MeasurementLocating position by Lat. and Long.Navigation AidsMERCATOR PROJECTIONMercator Proj

3、ection is based on that of a cylinder which has its point of tangency at the equatorOnly the equator is true to scale and free of distortionLets see why?MERCATOR PROJECTIONCharacteristics of the Mercator Projection:All Meridians are straight and parallel linesParallels of Latitude are also straight

4、and parallel linesA Straight line drawn between any two points on the chart is called a rhumb line (A curved line cutting all meridians at the same angle)There is no constant scale, areas in the northerly areas are exaggerated. For example, Greenland looks about the size of Africa, but in reality it

5、 is about an 1/8 of the sizeMERCATOR PROJECTIONSince we need a more accurate way to navigate with maps, we need to look at the Transverse Mercator ProjectionThis type of projection is used for air navigationMercator ProjectionTransverse MercatorTRANSVERSE MERCATORPoint of Tangency is a meridian of L

6、ongitude rather than the Equator, thus more options are available Any of the 360 meridians of longitude can be selected as the point of tangency for the chart projectionIn this case, the chart is more accurate along the selected meridianAccurate in depicting scale, especially charts covering a small

7、 geographical areaTRANSVERSE MERCATOR PROJECTIONTRANSVERSE MERCATORMAPS AND CHARTSMaps Based on the Transverse Mercator ProjectionVTA: VFR Terminal Area Chart Accurate scale only on small geographic areas Published for airports classified as controlled airspace Scale: 1:250 000 ( 1” to 4 SM)LAMBERT

8、CONFORMAL CONICThe basic idea of the Lambert Conformal is that of a cone superimposed over the surface of a sphereThe angles between meridians and parallels will be the same on the chart as on the groundCharacteristics of the Lambert Conformal Conic Projection:Meridians are curves or straight lines

9、converging at the polesParallels of latitude are curves which concave towards the nearest poleScale of distance is uniform throughoutStraight line drawn between two points can be assumed to be an arc of a great circleLAMBERT CONFORMALLAMBERT CONFORMALLAMBERT CONFORMAL PROJECTIONMaps based on the Lam

10、bert Conformal ConicVNC: VFR Navigation Chart For visual navigation, useful at lower altitudes & slower speeds, 40 maps cover the entire country Little distortion compared to Transverse Mercator Scale 1: 500 000 (1” to 8 SM) MAPS AND CHARTSMaps based on the Lambert Conformal ConicWAC:World Aeronauti

11、cal ChartFor visual navigation, useful for flights at higher altitudes and greater speedsDepicts sizeable portion of countrys geographical area, 18 charts cover the entire countryScale: 1: 1 000 000 ( 1” to 16 SM)MAPS AND CHARTSMaps used displaying Navigation AidsLow Enroute Charts (LO):Aeronautical

12、 radio navigation information over designated airways systemsFor use up to but not including 18 000 feet ASLNo cities or topographical features, only navigation aids, airways and communication frequenciesScale not constant, varies to suit each chart10 charts cover entire countryMAPS AND CHARTSMaps u

13、sed displaying Navigation AidsHigh Enroute Charts (HI):Aeronautical radio navigation information over designated airways systemsFor use at 18 000 feet ASL and aboveNo cities or topographical features, only navigation aids, airways and communication frequenciesScale not constant, varies to suit each

14、chart6 charts cover entire countryMAPS AND CHARTSLATITUDERunning East / West that parallel to the top and bottom of the chartMeasurements are actually lines of longitude along a line of latitudeEach degree is displayed in big numbers below lineLine without a number between two lines with numbers is

15、the 30” line1 minute of latitude = 1NMMAPS AND CHARTSLONGITUDE Divided the same way as latitudeMeasurements are actually lines of latitude along a line of longitudeExcept the degrees, minutes & seconds get smaller (to converge) the further north or south you go from the equatorThus never use a line

16、of Latitude to measure distanceWHY a line of latitude?MAPS AND CHARTSSymbols used on the map can be found in the map legend or in the CFSIf a symbol is located along your route, you must identify itThis will be useful in situational awareness using info from the mapTOPOGRAPHIC SYMBOLSMAPS AND CHARTS

17、VNC, WAC and VTA charts use various ways to display elevationHypsometric Tinting is used on VNC, WAC and VTA navigation chartsThe color coding represents increasing elevations in thousand foot (300 meter) incrementsELEVATION RELIEFMAPS AND CHARTSContour lines join areas of equal elevation (ASL)Spot

18、heights give even more elevation info by giving info for specific pointsELEVATION RELIEFMAPS AND CHARTSHighest ElevationGiven in latitude and longitudeInfo can be found on the legend of the mapELEVATION RELIEFMAPS AND CHARTSMAPS AND CHARTSLocating position using latitude and longitude:Latitude is always firstExpressed in North and SouthLongitu