The first time I saw an aeronautical chart, best I can recall, was at the little airport café in Half Moon Bay, California, while waiting for a table. The coastal mountains and cities scattered around San Francisco Bay were easily recognizable. But superimposed on that familiar landscape were cryptic numbers, strange symbols, and overlapping circles that hinted at an entirely different world in the skies above.

“It looks pretty complicated, doesn’t it?” says Brendan Quinn-Narkin, a commercial pilot and certified flight instructor in Northern California. Quinn-Narkin sells instructional videos for pilots online, and he recently volunteered to help me make sense of these maps, which pilots use for planning and navigation.

In the United States, aeronautical charts are published by the FAA, the Federal