Definition
Describing a map projection or display in which small shapes and angles on the surface of the Earth are preserved accurately, so that features on the chart match the true angular relationships of features on the ground. Sectional and other aeronautical charts are conformal, allowing pilots to measure courses and bearings directly on the chart with confidence that the angles are correct.
Plain English
A chart is conformal when the angles and shapes shown on it match the real angles and shapes on the ground, so directions you measure on the chart are true to what's actually out there.
Context Anchor
Seen in discussions of aeronautical chart projections, especially when learning how aviation charts represent the curved Earth on a flat page.
Derivation
From the Latin 'conformalis,' meaning 'having the same shape.' The root 'forma' means 'shape' or 'form.' A conformal chart keeps the same shape as the ground it represents — at least locally — which is exactly what a pilot needs when measuring courses.
Why Pilots Care
Enables accurate measurement of headings, courses, and bearings directly from the chart without angle distortion.
Analogy
Think of a small drawing printed on flexible material. If the material is stretched carefully, the tiny shapes may still look right nearby, even though the whole sheet is no longer a perfect match in size everywhere.
Intuition Check
Conformal does not mean perfectly accurate in every way. It means small shapes and local angles are preserved, while distance and area may still change across the chart.
Example Sentence 1
Sectional charts use a Lambert Conformal Conic projection, which keeps angles accurate over the area covered by the chart.
Example Sentence 2
On the conformal chart, the runway heading matched the compass reading without adjustment for projection error.