Definition
The continuous oversight of ground-based navigation aids (such as VORs, ILSs, and NDBs) by the FAA's flight inspection and air traffic system to confirm each facility is transmitting accurate, usable signals. When a facility's signal falls outside tolerance, monitoring equipment either removes the identifier, shuts the facility down, or alerts controllers so pilots can be advised it is unreliable or out of service.
Plain English
The FAA constantly checks that navigation stations on the ground are working correctly. If a station's signal becomes unreliable, the system either turns it off or warns pilots not to use it.
Context Anchor
Seen when planning instrument flights, reviewing approach procedures, checking current flight notices, or confirming whether a navigation station is available for use.
Derivation
“Monitor” comes from a word meaning “to warn” or “to remind.” That fits the aviation meaning: the system is watched so someone can be warned if the navigation signal should not be used.
Why Pilots Care
Failure to monitor can result in undetected signal errors leading to course deviation or unsafe approaches.
Grounding Statement
A navigation facility may still be physically present, but pilots need to know whether it is actually being checked and considered reliable at that time.
Intuition Check
Do not read “monitoring” as the pilot simply paying attention to the instruments. Here it means the navigation equipment itself is being checked for proper operation.
Example Sentence 1
Because of continuous monitoring of navigation facilities, the VOR's identifier was automatically removed when the signal drifted out of tolerance.
Example Sentence 2
The checklist requires monitoring of navigation facilities before entering the final approach segment.