What characterizes a reference plane in navigation?

A reference plane in navigation is characterized by having flat surfaces that extend to infinity. This concept is fundamental because a reference plane serves as a baseline from which measurements, such as distances or angles, can be made. By defining a flat, infinite surface, navigators ensure consistency in calculations and navigational references. This allows for accurate positioning and orientation, critical in navigation and piloting, especially over large distances like those encountered at sea.

The notion of having an infinite extent is important as it diminishes the impact of local variations in terrain or elevation. Instead of being constrained by immediate landscape features, navigators can rely on this idealized reference for a stable frame of reference when plotting courses or calculating navigational data. This consistency is why a flat surface extending indefinitely is a core characteristic of reference planes in navigation.