Definition
Radio signals broadcast from a ground-based navigation transmitter (such as a non-directional beacon) that an aircraft receiver detects and uses to determine direction or position relative to the transmitter station.
Plain English
Steady radio signals sent out from a fixed station on the ground so aircraft can find their direction or location relative to that station.
Context Anchor
Seen in radar and air traffic control discussions, especially when approach, departure, or center controllers identify and track an aircraft.
Derivation
Beacon comes from the Old English beacen, meaning a sign or signal — originally a fire lit on a hilltop to guide travelers or warn of danger. A radio beacon does the same job invisibly: it broadcasts a steady signal that pilots can home in on, just as sailors once steered toward a lighthouse.
Why Pilots Care
Accurate beacon signals enable controllers to maintain safe separation between aircraft and provide effective guidance during approaches and departures.
Analogy
A beacon signal is like an electronic name tag that answers when air traffic control asks, “Who are you?” It can also include the aircraft’s reported altitude.
Intuition Check
Do not confuse beacon signals with a rotating airport beacon or a light-gun signal from a control tower. Here, “beacon” means an electronic radar reply from the aircraft.
Example Sentence 1
The pilot tuned the receiver to the airport's beacon signals to confirm bearing during the approach.
Example Sentence 2
During the approach, intermittent beacon signals caused the controller to request a transponder check.