Definition
Routes that follow the shortest path between two points on the surface of the Earth, defined by an arc of a circle whose center is the center of the Earth. In long-range RNAV navigation, Great Circle tracks are the reference paths flown between waypoints to minimize distance.
Plain English
The shortest path between two points on a round Earth. Because the Earth is a sphere, the shortest route between two distant places is not a straight line on a flat map but a curve that bends toward the poles.
Context Anchor
Seen in random area navigation (RNAV) route planning, where a route may be built directly between navigation points instead of following published airways.
Derivation
A 'great circle' is any circle drawn on a sphere whose center coincides with the center of the sphere. The equator is one example; any line of longitude paired with its opposite is another. Any other circle on the sphere is a 'small circle.' The term comes from geometry, not aviation, but it underpins long-range navigation.
Why Pilots Care
Following these tracks reduces total distance, saving time and fuel on long flights.
Analogy
Stretch a string tightly between two cities on a globe. The path the string takes is a Great Circle. On a flat wall map, that same path looks like a curve that bends north or south.
Grounding Statement
On the round Earth the shortest path between far-apart points is never a straight line on a flat chart.
Intuition Check
Great Circle does not mean just a big circle drawn on a chart; it means a circle around the earth that would divide the globe into two equal halves. Track here means the aircraft’s path over the ground, not marks left behind.
Example Sentence 1
The flight plan from Los Angeles to Tokyo follows a Great Circle track that arcs north toward Alaska before descending into Japan.
Example Sentence 2
The chart displayed the great circle track as a curved line across the ocean.