A Lambert conformal conic projection (LCC) is a conic map projection, which is often used for aeronautical charts. In essence, the projection superimposes a cone over the sphere of the Earth, with two reference parallels secant to the globe and intersecting it. This minimizes distortion from projecting a three dimensional surface to a two-dimensional surface. Distortion is least along the standard parallels, and increases further from the chosen parallels. As the name indicates, maps using this projection are conformal. Pilots favor these charts because a straight line drawn on a Lambert conformal conic projection consistently and properly shows the true bearing between points. However aircraft will fly great circle routes which are the shortest distance between two points on the surface of a sphere. On a Lambert chart, this will generally be a curved line which must be separately calculated to ensure that correct intermediate waypoints are identified.
