Aircraft Trajectories Don't Follow a Straight Path on a Global Chart
Plane Flight Routes: Straight as an Arrow... Sort Of
Plane flights don't always follow straight paths on maps, and this misconception can be attributed to the way we represent the world. The Earth, being a sphere, is flattened into a two-dimensional map, often using the Mercator projection. This method, while preserving compass bearings as straight lines, distorts the appearance of the shortest routes, known as great-circle routes, making them appear curved.
The flight path from Los Angeles to Istanbul, for instance, is not a straight line on a map but follows a big, arcing path. This deviation from a direct eastward path can come as a surprise. In fact, this route often takes planes over Greenland, a location that can be seen from the flight.
The Mercator projection is notorious for distorting the sizes and shapes of landmasses, including Greenland, making it appear larger than it is in reality. This distortion is a factor that contributes to the misconception that plane flight routes are not straight lines.
In reality, the Earth's spherical shape and the distortions introduced by the Mercator projection result in flight paths that look curved on maps but are actually the shortest routes in three dimensions. Pilots follow the great-circle route to minimize distance and fuel consumption, even though on the Mercator map it appears as a curved line rather than straight.
The assumption that the shortest route between two points is always a straight line is not always accurate. The straight line hypothetical flight path from Los Angeles to Istanbul, when plotted on a map that accurately represents the Earth's curvature, would appear curved. This switch between three-dimensional, non-Euclidean geometry and two-dimensional Euclidean geometry is a fascinating aspect of navigation and cartography.
In conclusion, the next time you see a plane flight path on a map that seems to zigzag or curve, remember it's not a deviation from the shortest route but a reflection of the Earth's spherical shape and the distortions introduced by the Mercator projection.
[1] Mercator Projection [2] Great-circle route
- The misconception that plane flight routes are straight lines can be attributed, in part, to the distortions introduced by the Mercator Projection, which is notorious for altering the sizes and shapes of landmasses and making the great-circle routes appear curved.
- In reality, pilots follow the great-circle route, which is the shortest route in three dimensions, despite its curved appearance on a two-dimensional Mercator map.
