Definition
On an instrument approach chart plan view, concentric rings are evenly spaced circles drawn around a central reference point (typically a navaid or airport) used to indicate distance from that point. They appear inside the Minimum Safe Altitude (MSA) circle and help the pilot quickly judge range from the reference fix.
Plain English
A set of circles, one inside the other, sharing the same center point. On an approach chart they show how far you are from a key point on the ground.
Context Anchor
Seen in plan-view diagrams and navigation displays where the pilot is looking at a top-down picture of position and distance.
Derivation
From Latin 'concentricus' — 'con-' meaning 'together' and 'centrum' meaning 'center.' So 'concentric' literally means 'sharing the same center.' Picture the rings on a target or the ripples from a stone dropped in water — same center, different sizes.
Why Pilots Care
Allows rapid visual estimation of distance to the airport or fixes, supporting situational awareness and timing during approaches.
Analogy
Like the rings on a dartboard or archery target — all sharing one bullseye, each ring a fixed distance from the center.
Intuition Check
Do not read concentric rings as just “several circles.” The important point is that all the circles have the same center.
Example Sentence 1
The concentric rings on the plan view showed the pilot was about 15 nautical miles from the VOR.
Example Sentence 2
I glanced at the concentric rings to confirm our position relative to the airport before starting the descent.