Navigation Aeronautical Charts

Sep 2012Lesson 5.3

Navigation

Aeronautical Charts

Reference

From the Ground UpChapter 7.4:Aeronautical ChartsPages 186 - 196

Introduction• Aeronautical charts are maps that show

important information for air navigation.

• Pilots need to know what kind of charts are available and how to read them.

Outline• Distance and Speed Units• Aeronautical Charts• Chart Types• Scale and Relief

Distance Units• Statute Mile (SM or Mi) = 5280 feet

• Nautical Mile (NM) = 6080 feet = one minute of latitude

• Kilometer (km) = 1000 meters

• 66 NM = 76 SM = 122 km

Speed Units• Miles per Hour (MPH) = statute miles

per hour

• Knots = nautical miles per hour

• Kilometers per hour (km/h)

Speed Units• Indicated Airspeed = speed on airspeed

indicator

• True Airspeed = Speed of aircraft relative to air

• Groundspeed = Speed of aircraft relative to ground

Aeronautical Charts

• A Map is a small-scale, flat-surface representation of a part of the earth’s surface

• When designed for navigational information, it is called a Chart

• Four basic elements in map construction:– Areas– Shapes– Bearings– Distances

• Mathematical basis on which maps are constructed are called projections; They show distortion because Earth is a sphere

Conic Projection

• Lambert Conformal Conic Projection– Cone superimposed over surface of a sphere;

imprint made from where cone touches surface

• Properties– Meridians converge toward nearer pole– Parallels are curves and concave toward nearer

pole– Scale is constant– Straight line is an arc of a great circle

Mercator Projection• Visualized as light shown from inside earth onto

cylinder touching equator

• Properties– Meridians and parallels are straight and parallel– No constant scale– Straight line on map is a rhumb line– Extreme exaggeration of areas in far north and south– Distances near equator are more precise

• Transverse Mercator– Cylinder rotated 90 degree to touch a meridian– Exaggeration at east and west areas– More accurate because closest meridian can be used

Chart Types• VFR Navigation Charts (VNC)

– Lambert Conformal Conic Projection– 1:500,000 scale

• World Aeronautical Charts (WAC)– Lambert Conformal Conic Projection– 1:1,000,000 scale

• VFR Terminal Area Charts (VTA)– Transverse Mercator Projection– 1:250,000– Only made for high-traffic areas

Chart Types• Enroute Charts (LO/HI)

– Enroute Low Altitude (LO) for below 18,000 ft– Enroute High Altitude (HI) for above 18,000 ft– Used for IFR

• Canada Flight Supplement (CFS)– Lists all aerodromes shown on VNC/WAC– Contains valuable information (runways,

aerodrome lighting, services, radio frequencies etc)

Scale• Relationship between unit of distance on map

to distance on earth that unit represents

• Representative Fraction– Most common method of expressing map scale– Ratio of unit of length of map to number of same

units on earth

• Graduated Scale– Line drawn on part of map and graduated to show

length of one mile on map

Relief• Representation of ground elevation

above sea level

• Ways of showing relief:– Layer Tinting– Contour Lines– Spot Heights

Next Lesson

6.1 – RadioRadio

From the Ground UpChapter 8.1:RadioPages 209 - 213