Best map projection for showing flight routes
To show the shortest flight route, use the gnomonic projection: every great circle, the shortest path on a sphere, is a straight line on it. The map covers less than a hemisphere, though, so a route to the other side of the world is better shown on an azimuthal equidistant map centred on the departure city.
Best choice: Gnomonic
Neither equal-area nor conformal, perspective azimuthal
The shortest path on a sphere is a great circle. On a gnomonic map every great circle is a straight line, which is why navigators planned long routes on it. The map covers less than a hemisphere, though.
- Area: distorted
- Shape: distorted
- Distances: distorted
- Angles and directions: distorted
- Continuity: partially
Also good
- Azimuthal EquidistantEquidistant
Centred on the departure city: the route is straight and the distance from the start is true to scale.
Open in the map labProjection guide
What to avoid
It draws the rhumb line, a constant-bearing route, as straight, so the shortest path looks like a detour.
See the problem on the map →A different goal or map shape? Change the answers in the finder →
Why planes fly in an arc
The shortest path between two points on a sphere follows a great circle. On a Mercator map these routes bend toward the pole, so a flight from Europe to North America looks like a detour. That is the map playing tricks: the curved route is shorter than the straight line drawn on Mercator.
The shortest route from London to Tokyo climbs to about 71° north, although both cities lie below 52°. It is also about 1,700 km shorter than the constant-bearing route. Real flight paths depart from the great circle because of winds, air corridors and regulations, but the great circle remains the starting point of planning.
Gnomonic or azimuthal equidistant
Each of these draws the shortest path as a straight line, but over a different range.
- Gnomonic: every great circle is straight, so you can draw the route with a ruler. Scale grows quickly toward the edge, and the map covers less than a hemisphere.
- Azimuthal equidistant centred on the departure city: every great circle leaving that city is straight, and the distance from it is true to scale. The map covers the whole world.
- Mercator: the straight line is the rhumb line, a constant-bearing route, not the shortest path.
How navigators used it
Navigators drew the great circle on a gnomonic chart and then transferred it in segments to a Mercator chart. On each segment they sailed or flew a constant course, which combined a short route with simple steering.
Frequently asked questions
Because the shortest path on the sphere between these cities follows a great circle that rises toward the Arctic. On a Mercator map the route looks like an arc, yet it is shorter than the straight line on that map. The route lab compares both lines.
No. The gnomonic projection projects the globe from the Earth's centre onto a plane, so it covers less than a hemisphere and its scale grows without limit toward the edge. In the route lab the map centres on the middle of the chosen route.
The shortest distance over the Earth's surface is the length of the great circle. The route lab computes it for a sphere with a radius of 6,371 km and compares it with the length of the rhumb line.
The best projection for other jobs
- Comparing country sizesEqual Earth
- Thematic and data mapsEqual Earth
- Wall maps and postersWinkel Tripel
- Navigation and compass coursesMercator
- Web maps and appsMercator
- Distances from one placeAzimuthal Equidistant
- The Arctic and AntarcticaAzimuthal Equidistant
- Oceans and currentsSpilhaus Projection
- Teaching geographyEqual Earth