How to read a sectional chart for the Part 107 test

Reading a sectional chart is part of what the Part 107 knowledge test expects. The Airman Certification Standards list aeronautical charts as a source of airport data, and airspace topics make up 15 to 25 percent of test items.

This guide covers the parts of a sectional you will use most: the grid, airports, airspace boundaries, obstacles and special use airspace, and what each means for a remote pilot.

What a sectional chart is

A sectional is the standard visual chart for pilots who navigate by looking outside. It is drawn at a scale of 1:500,000, where one inch on the chart equals 6.86 nautical miles, or roughly 8 statute miles.

Each sectional is named after a major city inside its coverage area. It shows airport data, navigation aids, airspace and terrain on one sheet.

The legend is your key. Most symbols on the chart can be decoded by checking it, and the chart margins carry extra information such as ATC frequencies and airspace details.

Latitude and longitude: finding the spot

Lines that run east and west are parallels of latitude. They measure how far north or south of the equator a point lies, in degrees.

Meridians of longitude run from pole to pole. They are measured east or west from the Prime Meridian at Greenwich, England, up to 180 degrees.

Any point can be described by its latitude and longitude. For the 48 contiguous states, latitude falls between 25 and 49 degrees north and longitude between 67 and 125 degrees west, so every position in the 48 contiguous states is north and west.

When a question gives coordinates, find the labeled latitude line and longitude line nearest to them first, then count the small tick marks between them to the exact spot.

Airport symbols and data blocks

Color tells you whether an airport has a control tower. Towered airports and their data are printed in blue; all other airports and their data are printed in magenta.

The airport data block printed next to the symbol packs several items into a few lines:

• Elevation: the highest point on the usable portion of the landing areas.
• Runway length: the longest active runway, shown in hundreds of feet. A runway of 8,070 feet is printed as 81.
• CT: the control tower primary frequency. A star next to it means the tower operates part-time.

Airspace depictions: Class B, C, D, E and G

Class B surrounds the busiest airports. It usually runs from the surface to 10,000 feet MSL and is built in layers, often compared to an upside-down wedding cake.

Each Class B sector is labeled in solid blue figures with the ceiling over the floor, both in MSL with the last two zeros dropped. A floor marked with a plus sign means the floor is above that altitude, not at it.

Class C sectors are labeled the same way but in solid magenta figures. A typical label of 40 over SFC means the sector runs from the surface to 4,000 feet MSL; 40 over 12 means from 1,200 to 4,000 feet MSL. A ceiling of T means the sector goes up to, but not into, the Class B above it.

Class C usually has a 5 nautical mile inner circle starting at the surface and a 10 nautical mile outer circle from 1,200 feet up to 4,000 feet above the airport elevation.

Class D surrounds airports with an operating control tower and is drawn with a blue dashed line. It generally extends from the surface to 2,500 feet above the airport elevation. Its ceiling is printed in MSL; a minus sign in front of the number means up to, but not including, that altitude.

Class E that starts at the surface around an airport is drawn with a magenta dashed line.

Class E with a floor of 700 feet AGL is shown by a shaded magenta band called a vignette. Where a floor other than 700 feet borders Class G, the band is blue. In most areas the Class E base is 1,200 feet AGL.

Class G is uncontrolled airspace. It runs from the surface up to the base of the Class E above it, so inside a magenta vignette the airspace below 700 feet AGL is typically Class G.

When Part 107 needs ATC authorization

Part 107 requires prior ATC authorization before you fly in Class B, Class C or Class D airspace, or inside the surface area of Class E airspace designated for an airport.

In most cases you do not need ATC authorization for other Class E airspace, and you do not need it for Class G.

The magenta vignette is the classic trap. A 700-foot Class E transition area is not a Class E surface area, so a drone flying below 400 feet AGL under it is normally in Class G.

Obstructions, terrain and maximum elevation figures

Obstacle symbols mark man-made vertical features such as towers. Sectionals typically show obstacles taller than 200 feet AGL, and the symbol is different for obstacles of 1,000 feet AGL or more.

Next to the symbol, the top of the obstacle is given in feet MSL, and its height above the ground is shown in parentheses below it. Check which of the two numbers a question is asking for.

The letters UC next to an obstacle mean it is under construction or reported but not yet verified.

Give towers a wide berth. Guy wires can extend about 1,500 feet out from a structure, so skeletal structures should be avoided horizontally by at least 2,000 feet. New towers may also be missing from your chart.

The numbers printed in each grid quadrant are Maximum Elevation Figures (MEF). An MEF is the highest elevation in that quadrant, including terrain and obstacles such as towers and trees. On sectionals a quadrant spans 30 minutes of latitude by 30 minutes of longitude.

MEFs are rounded up to the next 100 feet and printed without the last two digits, so a figure read as 28 means 2,800 feet.

Special use airspace and other areas

Special use airspace is shown on the chart with its type and a name or number placed inside or right next to the area.

• Prohibited areas (P followed by a number, such as P-40): flight is not allowed. They exist for security or national welfare reasons.
• Restricted areas (R followed by a number, such as R-4401): flight is not wholly prohibited but is subject to restrictions, often because of invisible hazards such as artillery firing or guided missiles.
• Warning areas: similar in nature to restricted areas, located from 3 nautical miles outward from the U.S. coast.
• Military operations areas (MOAs): named rather than numbered, such as Camden Ridge MOA. Their times, altitudes and controlling agency are on the back of the sectional.
• Alert areas (A followed by a number): may contain a high volume of pilot training or unusual aerial activity. Use caution.
• Controlled firing areas: not charted at all, because their activities stop when an aircraft approaches.

What special use airspace means for a drone

For a drone, prohibited and restricted areas are off limits unless you have permission from the using or controlling agency.

Military training routes appear as lines labeled IR or VR. A four-digit number means no segment is above 1,500 feet AGL; three or fewer digits mean at least one segment is higher.

A step-by-step method for chart questions

Use the same short routine on every chart figure so you do not skip a detail under time pressure.

1. Read the question twice and note exactly what it asks for: a class of airspace, an altitude, a frequency or a location.
2. Find the point on the figure. If coordinates are given, locate the nearest labeled latitude and longitude lines first, then count tick marks.
3. Identify the boundary lines around that point: blue dashed for Class D, magenta dashed for Class E at the surface, and magenta or blue vignettes for Class E floors of 700 or 1,200 feet AGL.
4. Read the altitude labels. Add two zeros to get feet MSL, and remember that airport elevation and MSL figures are not the same as height above the ground.
5. Check the legend and the chart margins for anything you cannot decode.
6. Decide what Part 107 requires: ATC authorization for Class B, C, D and Class E surface areas; permission for prohibited or restricted areas.

Common mistakes

• Mixing up MSL and AGL. Airspace labels and obstacle tops are in MSL, while the Part 107 altitude limit is 400 feet above ground level.
• Treating the magenta vignette as airspace that needs authorization. It marks a Class E floor of 700 feet AGL, not a surface area.
• Forgetting the plus sign or minus sign in front of a figure. A plus means above that altitude; a minus in Class D means up to but not including it.
• Reading an MEF as a height above the ground. It is the highest elevation in the quadrant, with the last two digits dropped.
• Assuming a magenta airport has no airspace around it. Color only tells you whether there is a control tower; the boundary lines tell you the airspace.

Frequently asked questions

Sources

Every fact in this guide is taken from these FAA publications. Check the current edition before your test.

• FAA-S-ACS-10B Remote Pilot Airman Certification Standards
• FAA-G-8082-22 Remote Pilot – Small Unmanned Aircraft Systems Study Guide
• FAA Aeronautical Chart User's Guide
• FAA Aeronautical Information Manual
• 14 CFR part 107