Definition
A circular symbol drawn on en route charts around a navigation aid (such as a VOR) to depict its location and identify it as a facility used for en route navigation rather than for terminal or approach use.
Plain English
A circle on an en route chart that marks where a navigation aid sits and shows it is used for navigating between airports, not for approaches into one.
Context Anchor
Seen in the plan view of instrument approach charts, especially where the chart shows how to transition from the en route environment to the approach.
Derivation
En route' comes from French, meaning 'on the way.' A facilities ring is simply the ring (circle) drawn around a facility (the navaid). The name is literal: a ring marking an en route facility.
Why Pilots Care
Lets the pilot quickly verify that suitable navigation and communication support exists along the entire route before departure.
Intuition Check
Do not read “ring” as a holding pattern, a protected airspace area, or something you fly around. Here it means a chart symbol that marks an en route navigation facility or fix.
Example Sentence 1
She identified the next fix on the chart by the en route facilities ring around the VOR.
Example Sentence 2
If the destination lies outside the en route facilities ring, additional navigation planning is required.