Definition
Radio transmissions broadcast from ground-based or satellite-based navigation aids that an aircraft's onboard receivers interpret to determine position, course, and distance relative to a fixed reference point. Common sources include VOR stations, ILS components, NDBs, DME, and GPS satellites.
Plain English
Radio waves sent out by navigation stations on the ground or from satellites. The aircraft picks them up and uses them to figure out where it is and where it's heading.
Context Anchor
Seen in instrument-panel discussions of the horizontal situation indicator, where heading information is combined with course or position information from a navigation source.
Derivation
Navigation comes from older words meaning to travel by ship, and signal comes from a word meaning a sign. In aviation, navigation signals are the signs the aircraft’s instruments receive to help show the way.
Why Pilots Care
They provide the raw information the HSI uses to show course and position when outside visual references are unavailable.
Intuition Check
Do not read “signals” here as hand signals or spoken instructions. In this context, navigation signals are electronic information received by the aircraft’s navigation equipment.
Example Sentence 1
The HSI displayed course and bearing information by interpreting navigation signals received from the selected VOR station.
Example Sentence 2
Weak navigation signals caused the HSI needle to fluctuate during the approach.