From Tbilisi

draw the way the plane flies.

draw how you think a flight out of tbilisi flies, then see the real route and the km you added

The shortest path on a globe is a great circle, a geodesic, so a flight curves toward the pole rather than running straight across a flat map. The map's straight line holds one compass heading, but it is the longer way.

Concepts: maps, geometry, sphere.

An interactive you play with one thumb, on Wundr.