Definition
On the plan view of an instrument approach chart, concentric dashed circles are nested rings drawn around the airport reference point that indicate the chart is not drawn to scale. Their presence tells the pilot that distances between symbols on the plan view cannot be measured directly off the chart and must instead be read from the labeled distances printed alongside fixes, courses, and route segments.
Plain English
A set of dashed rings, one inside another, all sharing the same center. On an approach chart, they are a visual warning that says 'this picture is not drawn to scale — use the printed numbers, not your eyes, to judge distance.'
Context Anchor
Seen in the plan view of instrument approach charts, especially where the chart is showing arrival areas and distances around a fix.
Derivation
Concentric comes from the Latin 'com-' (together) and 'centrum' (center) — meaning 'sharing the same center.' Dashed simply describes the broken-line style of the circles. Together the term describes nested rings drawn with broken lines around a common center point.
Why Pilots Care
Allows quick visual estimation of distance to the airport or fix during approach planning and orientation.
Analogy
They look like a bullseye drawn with broken lines: several rings around one center point.
Intuition Check
Do not read “concentric” as meaning the circles are the same size; it means they share the same center. Do not assume the dashed circles are a flight path; on the plan view, they usually mark charted areas or distance rings.
Example Sentence 1
Briefing the approach, the pilot noted the concentric dashed circles on the plan view and reminded himself to use the printed distances rather than estimating by eye.
Example Sentence 2
Using the concentric dashed circles on the plan view, the pilot confirmed the airport was five miles away.