Chart Symbols and Colors

Terrain elevation color shading

Sectional charts use a graduated color scale — sometimes called elevation tinting — to show terrain height at a glance without requiring the reader to hunt for individual elevation numbers. Lower elevations are shaded in lighter greens, rising through tan and yellow tones at moderate elevations, and into darker brown tones for the highest terrain on the chart. This tinting is a quick visual cue only — for the specific highest point of concern in a given area, a pilot relies on the Maximum Elevation Figure, not the color alone.

Each chart is also divided into a grid of quadrangles, and every quadrangle prints its own Maximum Elevation Figure (MEF) — a large bold number for thousands of feet paired with a smaller number for hundreds of feet, giving the height in feet MSL of the highest feature (terrain or obstacle, including a safety buffer) within that quadrangle. A quadrangle printed "8 2" means a Maximum Elevation Figure of 8,200 feet MSL — nothing charted in that quadrangle is taller than that figure, making it a fast way to check for terrain or obstacle risk in unfamiliar territory before ever looking at individual symbols.

Airport symbols: shape and color meaning

Airports are shown with circular symbols whose color indicates whether the airport is towered or non-towered: airports depicted in blue are towered — meaning they have an operating air traffic control tower and are typically surrounded by Class B, C, or D airspace — while airports depicted in magenta are non-towered, with no operating control tower (though they may still be surrounded by Class E airspace with a surface area, as covered in the next lesson). The symbol's shape also carries information: a filled circle with short perpendicular marks depicts a hard-surfaced runway, while an open circle with small extensions depicts a soft or unpaved runway. Larger, more detailed symbols are used for airports with more runways or facilities; small symbols mark minor airstrips.

It's easy to confuse this magenta/blue airport-color coding with the similar-looking magenta and blue lines used for airspace class boundaries in the next lesson — they use the same two colors for a completely different purpose. An airport symbol's color tells you whether that airport has a tower; an airspace boundary line's color and style tell you which class of airspace surrounds it. The two are related in practice (towered airports are usually inside Class B, C, or D) but are not the same piece of information.

Obstacle symbols: the basics

Obstacles — towers, tall structures, and similar hazards to flight — are shown with small black symbols: a single obstacle uses one marker shape, while a group of obstacles clustered together uses a different marker indicating multiple structures in that immediate area. Every charted obstacle prints a height figure nearby, and taller or more significant obstacles (generally 1,000 feet AGL and above) are shown with a larger version of the same symbol to make them stand out at a glance. The exact numbers, height reference conventions, and how to read an obstacle's full data label are covered in depth in the next lesson on airports, towers, and obstacles.

Cultural and other features: roads, railroads, powerlines, and hydrography

Beyond airspace and airports, a sectional chart shows the everyday ground features useful for visual navigation and hazard awareness. Roads and highways appear as thin black or gray lines, often following recognizable real-world routing. Railroads use a distinct black line with perpendicular tick marks (resembling a ladder or railroad-tie pattern). Powerlines — a genuine hazard for low-altitude sUAS flight — are shown as a fine black line, sometimes with small tower-like marks along its length, though not every powerline in existence is necessarily charted, especially smaller local distribution lines. Water features — rivers, lakes, and coastlines — are shown in blue, distinguishing hydrography clearly from any of the black cultural or obstacle symbols.

Real-world scenario: a fast visual risk scan before departure

A remote pilot preparing to fly an agricultural mapping mission in unfamiliar terrain pulls up the sectional chart for the area. Before looking at any individual symbol, the pilot notes the terrain shading trending from green to tan across the field — a gentle rise in elevation, not a mountain. Checking the Maximum Elevation Figure for that quadrangle confirms a ceiling of 1,400 feet MSL for anything charted there. Scanning the immediate flight area, the pilot spots one single-obstacle symbol near the field's northeast corner with a printed height label, and a thin black line with small tower marks crossing the southern edge of the field — a powerline to route around during low-altitude passes. This whole scan takes under a minute and flags every major hazard before the pilot even needs the full chart legend.