Navigation Aids

A navigational aid (also known as aid to navigation, ATON, or navaid) is any sort of marker which aids the traveler in navigation; the term is most commonly used to refer to nautical or aviation travel. Common types of such aids include lighthouses, buoys,fog signals, and day beacons.

According to the glossary of terms in the United States Coast Guard Light list, an Aid to Navigation is any device external to a vessel or aircraft specifically intended to assist navigators in determining their position or safe course, or to warn them of dangers or obstructions to navigation.

A lighthouse is an easily recognized aid to navigation.

Instrument landing system

An instrument landing system (ILS) is a radio beam transmitter that provides a direction for approaching aircraft that tune their receiver to the ILS frequency.

It is a ground-based instrument approach system that provides precision lateral and vertical guidance to an aircraft approaching and landing on a runway, using a combination of radio signals and, in many cases, high-intensity lighting arrays to enable a safe landing during instrument meteorological conditions (IMC), such as lowceilings or reduced visibility due to fog, rain, or blowing snow.

fog, rain, or blowing snow.