Definition
A ground-based or space-based facility that transmits signals enabling aircraft to determine position, track a course, or fly an instrument approach. Common NAVAIDs include VOR, DME, NDB, TACAN, ILS, and GPS/WAAS sources used as the basis for published routes and procedures.
Plain English
A signal source on the ground or in space that an aircraft's instruments can use to figure out where it is and where it's going.
Context Anchor
Seen on instrument procedure charts, en route charts, and avionics displays when a route or approach is based on a specific navigation source.
Derivation
A blend of 'navigation' and 'aid.' Navigation comes from the Latin navigare, 'to sail or steer a ship.' A NAVAID is literally an aid to steering — the modern airborne equivalent of a lighthouse or channel marker.
Why Pilots Care
Provides the primary electronic guidance required for instrument approaches and en route navigation when visual references are unavailable.
Intuition Check
Do not read “aid” as something optional or merely helpful here. In instrument flying, a NAVAID can be the required navigation source that defines where the aircraft should go.
Example Sentence 1
The approach is based on a single primary NAVAID, so the pilot confirmed it was in service before beginning the procedure.
Example Sentence 2
Primary NAVAIDs supply the main course guidance for the published procedure.