PILOT NAVIGATION

Senior/Master Air Cadet

4. MAP READING

Introduction

We have seen that despite the development of very accurate navigation systems there is still

no substitute for map reading

However all of the errors that can be made on the ground are just as likely to

be made in the air

Introduction

The extreme mental pressures in the airborne environment demand that decisions have to

be made promptly

Therefore it is rare to navigate by map reading alone - other equipment is used as

well

Weather

Is a major influence on the accuracy of map reading, and at times may

prohibit its use

Weather

The lower the visibility, and the greater the cloud cover, the more difficult the map reading will be. At high altitude even

moderate cloud cover can make map reading impossible

Aircraft Altitude

Has a major effect on map reading requirements and

technique

Features which are ideal at low level are useless at high level,

& vice versa

GOOD

BAD

Low Level

At low level it is important to chose features that have vertical extent

CHIMNEYS

MASTS

WINDMILLS

SMALL HILLS

This is to enable them to be seen before the aircraft arrives overhead the feature

High Level

At high level it is important to chose large features that have definition and contrast

to stand out from a background

Lakes

Woods

Islands

A further consideration is the difficulty at high level of obtaining an “on top” fix with an aircraft of limited downward visibility

Unique Features

Very large errors can be introduced into map reading simply by confusing one feature on

the map with another

For this reason villages are rarely used

We need more unique features

These can be

Power Stations

Bridges

Can you think of anymore?

Colour, Contrast & Season

Of all natural features, rivers and coast lines are the most useful, especially in

poor weather

This is because they show the greatest contrast & colour between themselves &

the land

Why?

Many land areas seen as ideal change their appearance with the seasons.

A wood in the summer will not be as obvious in the winter

A wooded area whichwas used as a turning-point during

Summer Camp would be much more difficult to identify in the winter when its

leaves had fallen

Snow changes everything including man made features

Snow has a dramatic effect onthe landscape, eliminating many

features and rendering many of the man-made line-features, such as

roads and railways, virtually invisible

Map Scales

In both military & civil aviation special maps are produced for map reading

from the air

These differ from OS maps in that they place more emphasis on those features

which are more easily identified from the air, such as airfields, towns, railway tracks and

masts.

HOWEVER THEY MUST BE UP TO DATE !

HOWEVER THEY MUST BE UP TO DATE !

HOWEVER THEY MUST BE UP TO DATE !

The choice of scale of your chosen map will depend on the speed of your aircraft

Most aircrew use the 1:500,000, widely known as the “half million”.

In general, the slower you fly, and the more detail you require, the larger scale

map you will use

For high-flying, long-range aircraft the opposite is true

Here, smaller scale maps reduce the number of sheets required

Map Symbols

SEA LEVEL

3000

2000

1000

500

914

610

305

152

FEET METRES

CIVILIAN

LIMITEDFACILITES

AIRFIELD

M

H

MICROLIGHT

G

MILITARY

AIRFIELD AVAILABLEFOR CIVIL USE

XDISUSED

HHELICOPTER

825(350)

1978(1031)

B3 A FL45 -FL246

PARACHUTING

UNLIT OBSTRUCTION & HEIGHT (FIGURES ARE HEIGHT ABOVE SEA LEVEL & (LOCAL GROUND LEVEL)

LIT OBSTRUCTION

AIRSPACE BOUNDARY A INDICATES THE AIRSPACE TYPE IE A-F

A

REPORTING POINTMANDATORY

ON REQUEST

BROOKLANDSE/E

GUILFORDVRP

SPECIAL ACCESS/ ENTRY EXIT

VISUAL REPORTINGPOINT

VOR

DME

TACAN

NON-DIRECTIONALRADIO BEACON

Timing Marks

In a modern sophisticated aircraft the navigation equipment will tell you where

to look if you become temporarily uncertain of your position (i.e. lost!)

In a simple aircraft we will not have this equipment and so rely on the stopwatch and

map

When planning a map reading flight it is normal to put marks along each leg at a

set time - such as 2 minutes

If you lose your place along track while map reading, consult your watch, work out your time in minutes since the last point, and that will tell you where to look on the

map.

2

4

6

8

A Tutor is flying from the railway junction near Stowmarket via the mast

South West of East Dereham to the lighthouse at Cromer

A route on a 1:50,000 map from an initial point (IP) at to a target on the river

near Allanton

Conclusion

In common with so many aspects of aviation , successful map reading will

benefit greatly from the amount of advanced planning

this will give you the best chance of recovery when you lose your way

Through study of the route

detailed preparation of your route

and the careful selection of the unique features on the ground