Definition
Radio signals transmitted from fixed navigation stations on the ground that aircraft receivers use to determine position, course, and bearing. Common sources include VOR, NDB, ILS, and DME stations, each broadcasting on specific frequencies that the aircraft's navigation equipment tunes to and interprets.
Plain English
Radio signals sent out by navigation stations on the ground. The aircraft picks up these signals and uses them to figure out where it is and where it's heading.
Context Anchor
Seen in instrument flying when an electronic flight display shows navigation guidance from a selected ground radio navigation source.
Why Pilots Care
These signals provide a reliable, independent navigation source that remains available when satellite signals are lost or jammed, supporting continued instrument flight and approach capability.
Grounding Statement
Picture a fixed radio station on the ground sending out a signal that the airplane can receive and turn into navigation guidance on the instrument display.
Intuition Check
Do not assume “navigation signals” always means GPS. Here, “ground-based” means the signal starts from a fixed transmitter on the earth’s surface.
Example Sentence 1
The VOR receiver picks up ground-based navigation signals from a station about 40 miles away and displays the aircraft's bearing to it.
Example Sentence 2
When GPS reception dropped, the crew reverted to ground-based navigation signals from the local ILS for the approach.