Definition
An in-flight investigation and evaluation of a navigational aid (such as a VOR, ILS, or NDB) to determine whether it is operating within established tolerances and is safe and reliable for use by pilots.
Plain English
A specially equipped aircraft flies set patterns near a ground-based navigation aid to check that the signals it transmits are accurate and trustworthy. If everything checks out, the aid stays in service. If not, it gets fixed or taken offline.
Context Anchor
Seen in FAA material about navigation aids, instrument procedures, airport systems, and changes to published flying procedures.
Derivation
From 'inspection' (Latin inspectio, 'a looking into'), conducted in flight rather than on the ground. The point is that some checks can only be done by actually flying through the signal the navaid produces.
Why Pilots Care
Confirms that the navigation signals and lighting pilots depend on meet safety standards before they are placed in service or returned to use.
Intuition Check
Do not read this as a general aircraft inspection before a flight. In this FAA use, flight inspection means an inspection carried out by flying an aircraft to test a navigation aid, signal, or procedure.
Example Sentence 1
The pilot heard 'ILS flight inspection in progress' on the ATIS and chose to fly the RNAV approach instead.
Example Sentence 2
A NOTAM warned pilots of possible signal fluctuations during the scheduled flight inspection of the VOR.