5.10 Sectional Chart Interpretation Exercises

Reading the Sectional Chart

The Part 107 knowledge test bundles several chart questions built on excerpts from the official Airman Knowledge Testing Supplement (sUAS), the printed legend-and-chart booklet the testing center provides. These are points you can lock in with practice, because the questions repeat a small set of skills.

Identifying Airspace by Color and Style

Work from the airport symbol outward, and let color and line style tell you the class:

Color discipline is the number-one trap. A magenta airport symbol is non-towered; a blue symbol is towered. A dashed magenta ring is a Class E surface area, so Part 107 authorization is required there — distinct from the faded magenta vignette, which marks Class E beginning at 700 feet AGL and needs no authorization for a sub-400-foot drone flight.

Reading Obstruction Data

Obstructions print two numbers — the top is the height in MSL (above mean sea level), the bottom in parentheses is the height in AGL (above ground level).

Worked example — label 2,560 (1,230): the top of the obstruction is 2,560 feet MSL and it rises 1,230 feet AGL. The ground at its base is therefore 2,560 − 1,230 = 1,330 feet MSL. To find ground elevation from any obstruction, subtract the AGL number from the MSL number.

A bolded obstruction number, or one marked with a tie-down/lightning symbol, flags a lighted or group obstruction; obstructions 1,000 feet AGL and taller are drawn with the heavier "tall" symbol.

Maximum Elevation Figures

The large number in the center of each grid quadrangle is the Maximum Elevation Figure (MEF), shown in hundreds of feet MSL. An MEF printed as 34 means 3,400 feet MSL is the highest known terrain or obstacle (plus a vertical buffer) anywhere in that quadrangle. Multiply the printed figure by 100.

Special-Use Airspace

Finding Coordinates

To read a point's latitude and longitude: locate the nearest labeled latitude line, count tick marks (each tick is 1 minute) north or south to your point; repeat for longitude east or west; then state it as, for example, N33°25′ W118°10′. The standard trap: in the contiguous United States longitude increases toward the west (to the left on the chart), so do not reverse east and west.

Typical Exam Questions

Expect prompts such as: "What class of airspace exists at [location]?"; "What are the floor and ceiling of the airspace at [location]?"; "What is the height of the obstruction at [location]?"; "Is Part 107 authorization required to fly at [location]?"; and "What is the Maximum Elevation Figure for the area around [location]?"

Test-Day Technique

1. Slow down — chart questions reward careful reading, not speed.
2. Use the legend in the supplement to confirm a symbol.
3. Check the color — blue versus magenta decides the airspace.
4. Multiply altitude labels by 100 where the convention applies (MEFs).
5. Identify the airport first, then work outward to the airspace.
6. Re-verify before committing your answer.

Reading Class E Altitude Tints Carefully

The most missed chart distinction is between the two magenta Class E depictions. A dashed magenta line drawn as a ring around an airport is a Class E surface area — controlled airspace down to the ground, where Part 107 authorization is required. A faded magenta vignette (a soft shaded band on the outside edge of the tint) marks Class E beginning at 700 feet AGL, leaving the airspace below it Class G, so a sub-400-foot drone flight there needs no authorization. Likewise a faded blue vignette marks Class E starting at 1,200 feet AGL.

Read which side of the band is shaded: the airspace transitions on the faded edge.

Floors and Ceilings in the Layer Cake

Class B and Class C airspace are drawn as stacked rings, each labeled with a ceiling over a floor in hundreds of feet MSL. A label reading 100 over 40 means that shelf runs from 4,000 feet MSL up to 10,000 feet MSL, with the airspace below 4,000 feet being something else (often Class E or G). A label with SFC as the floor means that ring extends down to the surface. For a drone pilot the practical question is usually whether the surface under your operating site is controlled; reading the innermost ring's floor answers it.

Common Chart Symbols Worth Knowing

Beyond airspace, expect a few recurring symbols. A small magenta flag marks a visual checkpoint. Victor airways appear as blue lines with a "V" designator. A boxed note near an airport gives the CTAF/Unicom frequency (often with a circled C) and the field elevation in feet MSL. Parachute, glider, and ultralight activity symbols flag areas of unusual traffic. Recognizing these keeps you from mistaking a checkpoint flag or airway line for an airspace boundary, which is exactly the kind of confusion the chart questions probe.

For the Exam: Practice on real charts — the free SkyVector website and FAA digital sectionals let you rehearse until airspace identification and obstruction math are automatic. The two facts that most often cost points are mixing up blue and magenta, and forgetting that MEFs and altitude labels are in hundreds of feet MSL.