52 RCACSGround School

NavigationPO 404 EO 3“Projections”

Introduction

Teaching Points Introduction to Maps Lambert Conformal Conic Projection Mercator Projection Transverse Mercator Projection Properties of a Map Types of Aviation Charts

Review Reference:

FTGU Chapter 7 Section D Pages 184-187

Introduction to Maps The surface of a sphere cannot be accurately projected onto a flat

piece of paper, like a map. So maps show some portion of the earth with distortion.

The four elements of a map are AREAS SHAPES BEARINGS DISTANCES

Depending on the purpose of the map one or more of these is preserved. 

There are two basic map types used for air navigation. LAMBERT CONFORMAL CONIC PROJECTION MERCATOR PROJECTION

Theory Put a cone over the surface of the earth. Imagine a light shining from inside the earth projecting an image

outward onto the cone. Unroll the cone and you have a Lambert Conformal Conic

Projection. Properties

Meridians of longitude converge toward the nearer pole. Parallels of latitude are curves that are concave toward the nearer

pole. The scale is almost perfectly uniform. A straight line drawn on this map is a GREAT CIRCLE. When drawing a straight line less than 300 NM take the track from

the center.

Lambert Conformal Conic System

Lambert Conformal Conic System

Mercator Projection THEORY

Place a cylinder over the earth so the only place it is touching is the equator.

Imagine a light shining from the center of the earth projecting an image outward onto the cone.

Unroll the cylinder and you have a Mercator Projection. Properties

Meridians of longitude are straight and parallel. Parallels of latitude are straight and parallel. There is no constant scale. A straight line drawn on this map is a RHUMB LINE. Areas in high latitudes are greatly exaggerated. Distances shown near the equator are fairly precise.

Mercator Projection

Your can overcome the problems of the Mercator projection by modifying the technique slightly. Pick a meridian of longitude and turn the cylinder sideways so it

touches the earth at only the chosen meridian. Now distance is accurate along this meridian and the distortion

occurs at the edges of the map. This is called a Transverse Mercator Projection.

Traverse Mercator Projection

Traverse Mercator Projection

Properties of a Map

Represents a portion of the earth. Has meridians of longitude and parallels of latitude. Scale. Relief Isogonic Lines. Communities, roads and railways. Aerodromes. Restricted areas. Compass Rose. Aeronautical Information.

Properties of a Map

Scale Scale is shown by a

representative fraction graduated scale.

Representative fraction 1: 500,000 means that one inch on the map is equal to 500,000 inches

on the ground. Graduated scale

printed on the border of the map

Properties of a Map

Relief There are three ways to show relief on a map.

LAYER TINTING Certain colors mean a certain range of elevations. On some maps it is

called a hypsometric tint scale. Water is always colored blue.

CONTOUR LINES They join places of equal elevation above mean sea level. The

closer the contour lines the steeper the slope. SPOT HEIGHTS

High elevations are marked by a dot with the spot height written beside the dot.

The highest spot height in a quadrant is usually printed in larger numbers than the other spot heights.

Contoured Relief Map

Coloured Relief Map

Types of Aviation Charts

VFR Navigation Charts (VNC)slow speeds at low altitudes.

scale is 1:500,000Lambert Conformal Conic Projection.

World Aeronautical Charts (WAC) visual navigation at high speeds and high altitudes.

scale is 1:1,000,000 Lambert Conformal Conic Projection.

VFR Navigation Chart

Types of Aviation Charts VFR Terminal Area Charts (VTA)

Published for those airports around which terminal class C airspace has been designated.

scale is 1:250,000 Transverse Mercator Projection.

Enroute Charts Low altitude charts

For altitudes less than 18,000 feet High altitude charts

For altitudes equal to or greater than 18,000 feet. They have information for radio navigation and very little visual

information. Its scale is not constant. Canadian Flight Supplement

A supplement to AIP Canada and lists all aerodromes shown on, VNC’s, and WAC’s. It also contains all kinds of valuable information related to aviation and is absolutely INVALUABLE to a pilot.

Questions?

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