Definition
Navigation guidance derived from radio signals transmitted by fixed stations on the ground, such as VOR, NDB, DME, and ILS facilities. The aircraft's avionics receive these signals and convert them into bearing, distance, or course information that the pilot uses to determine position and track a desired route.
Plain English
Position and course information that comes from radio stations on the ground. The aircraft picks up their signals and shows the pilot which way to fly and how far away the station is.
Context Anchor
Seen in navigation instrument discussions when comparing aircraft equipment, satellite navigation, and navigation sources located on the ground.
Derivation
“Ground-based” means based on, or located at, the ground. “Navigation” comes from older words connected with guiding a ship on a voyage. In aviation, the idea is the same: guidance for getting from one place to another, with the source of that guidance fixed on the Earth’s surface.
Why Pilots Care
Even in the GPS era, ground-based navigation aids remain a primary or backup means of navigation. Knowing whether your guidance is coming from a ground station or a satellite affects how you interpret instrument indications, plan for failures, and choose alternate routes.
Grounding Statement
Picture a fixed station on the ground sending out information that an aircraft can receive and use to help find its way.
Intuition Check
Do not read “ground-based” as meaning advice from a person standing on the ground. Here it means the navigation source itself is located on the Earth’s surface, not in space and not only inside the aircraft.
Example Sentence 1
When the GPS failed, the pilot reverted to ground-based navigation information from the nearby VOR to continue the flight.
Example Sentence 2
Preflight planning included checking availability of ground-based navigation information along the route in case of satellite outage.