Definition
A specialized airborne system, carried in flight inspection aircraft, that automatically measures, records, and analyzes the signals from ground-based navigation aids (such as ILS, VOR, DME, and NDB) to confirm they are operating within published tolerances and are safe for pilots to use.
Plain English
Equipment in special inspection aircraft that flies near navigation transmitters on the ground and checks whether their signals are accurate and reliable enough for pilots to depend on.
Context Anchor
Seen in FAA acronym lists and in discussions of FAA flight inspection work, especially when checking navigation and landing guidance used by aircraft.
Derivation
Automated -- runs the checks and records data without a human doing it manually. Flight inspection -- the practice of testing a navigation aid by flying past it and measuring what the aircraft receives. Together: a system that performs that inspection job automatically while in flight.
Why Pilots Care
Every ILS approach, VOR radial, and DME distance a pilot relies on has been signed off as accurate by a flight inspection. AFIS is what makes that trust possible. When a NOTAM says a navaid is unusable or restricted, it is often because flight inspection has not yet confirmed it.
Intuition Check
AFIS does not mean a service that gives pilots flight information in this context. Here, it means a system used to inspect and verify aviation guidance equipment from an aircraft.
Example Sentence 1
The VOR was returned to service after the flight inspection aircraft used its AFIS to verify the signal was within tolerance.
Example Sentence 2
Maintenance crews rely on AFIS data before returning a VOR to service after an outage.