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Some reasonable requirements for a map could be:

• Distances must be able to be measured correctly

If the distance between two points is measured to be 5 cm somewhere on

the map. If this corresponds to, for example, 500 km on the globe, then 5

cm between two points everywhere on the map must correspond to 500
km on the globe

• Angles must be able to be measured correctly (conformal)

The angle between two straight lines on a sphere is found by inserting a

plane that is tangent to the sphere at the intersection of the two lines and

then projecting the lines perpendicularly onto the plane.

The angle between the two lines on the sphere is now defined as the angle

between the two lines in the plane inserted.

• A straight line between two points shows the shortest path between the

two points

The shortest path between two points on the globe is along a great circle.

A great circle on a sphere is a circle that has its center in the center of the
sphere. A circle along the equator, for example, constitutes a great circle.

The above requirements are therefore only met if great circles are depicted

as straight lines.

• Areas are depicted correctly

Area determination using the map, that one area has twice the area of
another, then this must be in accordance with reality.

9.4.1.1 Requirements for maps

A map is defined as an image of the earth's surface projected onto a flat surface.

All types of maps are constructed to show the areas in question as correctly as

possible.

In practice, this is done by a map projection, which is an image of the earth's
surface reduced according to a certain ratio.

Flyveteori PPL(A)(UL)/LAPL Henning Andersen, Midtjysk Flyveskole© 2025 815