What is a disadvantage of the Gnomonic projection?

The Gnomonic projection is a type of map projection where all great circles are represented as straight lines, making it useful for certain navigational purposes. However, because of the nature of this projection, rhumb lines (which represent straight path courses across the Earth) appear as curved lines. This is a significant disadvantage, as navigating using rhumb lines becomes complicated and less intuitive when they are not displayed as straight lines on the map, complicating route planning for mariners. The curvature of rhumb lines can lead to navigational errors if a navigator assumes they can sail in a straight line when they actually must adjust their course.

In contrast, the Gnomonic projection shows great circles accurately as straight lines, which is beneficial for long-distance navigation. However, this advantage does not mitigate the confusion or complexity introduced by the representation of rhumb lines, which is a clear drawback of the projection in practical applications. The projection is typically not preferred for detailed navigation over longer distances where rhumb lines play an important role.