Beacon is an easily seen light or a radio signal. A beacon is used especially to aid ships or aircraft in finding a safe course. The main types of beacons for ships are lighthouses and navigational buoys.
Aeronautical beacons guide airplanes and are classified as (1) airway, (2) airport, and (3) landmark beacons. These beacons must have long-range lights; have standard color characteristics; operate from sunset to sunrise; and mark (a) a route leading to an airport or field, (b) an airport or landing field, or (c) a point for taking bearings, a landmark, or an area which presents hazards to flying.
Radio beacons on coasts help ships stay on course, especially in foggy conditions. Each radio beacon sends a signal using its own code letters. When a ship receives the signal, it turns its direction finder one way, then another, until it discovers the direction from which the signal is strongest. An officer then draws a line toward that point on a map and plots the direction of other signals in the same way. The point where the lines cross shows the location of the ship.
