Definition
Any ground-based or space-based facility, system, or device that provides guidance information to aircraft for the purpose of navigation. Examples include VORs, NDBs, ILS, DME, and GPS satellites.
Plain English
A piece of equipment, on the ground or in space, that sends out signals an aircraft can use to figure out where it is or where it's going.
Context Anchor
Seen on charts, during flight planning, and in Notices to Air Missions when a beacon, signal, or other navigation source is working, limited, or out of service.
Derivation
From Latin 'navigare' (to sail, navigate) plus 'aid' (something that helps). The term originally covered marine beacons and lighthouses; in aviation it carries the same idea — an external helper that tells you where you are.
Why Pilots Care
Navigation aids allow safe flight when visual references are unavailable and support precise routing and approaches.
Intuition Check
Do not read aid as a person helping you navigate. Here, a navigation aid is a source of position or guidance information used for navigation.
Example Sentence 1
Before departure, the pilot checked NOTAMs to see if any navigation aids along the route were out of service.
Example Sentence 2
Satellite navigation aids now provide more accurate guidance than older ground-based systems.