What is convergency in navigation?

Convergency in navigation refers to the change of direction experienced along east-west tracks, particularly as one moves north or south on the Earth's surface. This phenomenon occurs because the lines of longitude converge as they approach the poles. Therefore, a vessel or aircraft traveling east or west will have to adjust its heading slightly if it is navigating along a path that follows the curvature of the Earth.

As one travels in a straight line along a latitude line, they will encounter a change in the actual track that needs to be maintained to stay on a constant latitude due to the convergence of the meridians. This adjustment ensures accurate navigation and helps maintain the intended course, especially over long distances. A good understanding of convergency is essential for navigators to ensure they remain on the correct path while accounting for the spherical shape of the Earth.