Which radar is used as a coastal navigation aid?

Surface search radar is utilized as a coastal navigation aid due to its capability to detect and track surface vessels and other objects in proximity to the coastline. This type of radar is designed to provide detailed information about the surface of the water, which is critical for safe navigation, especially in areas where maritime traffic is dense or where navigational hazards may be present.

Surface search radar operates by emitting radio waves that bounce off objects on the water's surface, allowing operators to identify obstacles, incoming boats, and land features. This functionality directly assists mariners in making informed decisions while navigating close to shore, improving safety, and preventing collisions.

The other types of radar mentioned serve different purposes that do not align with coastal navigation aids. Air search radar focuses on monitoring aircraft in the airspace, approach radar is primarily used for guiding aircraft during the landing phase at airports, and missile guidance radar is specifically designed for tracking and directing missiles, which is unrelated to maritime navigation.