Before a Part 107 remote pilot can legally fly, they must understand the airspace around them — and sectional aeronautical charts are the primary tool for visualizing that airspace. Sectional charts pack an enormous amount of information into compact symbols, and airport depictions are among the most information-dense symbols on the chart. Knowing how to read these symbols tells you not just where airports are, but what class of airspace surrounds them, how high the traffic pattern sits, whether a control tower is present, and what services pilots can expect. Every one of these details has direct implications for where a drone operator may fly and whether prior authorization is required.
This article walks through every element of how airports appear on VFR sectional charts — the colors, symbols, rings, and data blocks — so you can read any sectional quickly and confidently on the Part 107 aeronautical knowledge test and in the field.
The Basic Airport Symbol
On a VFR sectional chart, airports are depicted using one of two primary geometric shapes. A circle with lines radiating outward like a compass rose (resembling a wheel with spokes) indicates a runway layout airport — the lines roughly represent the actual runway configuration as seen from above. Simpler airports with fewer runways may appear as a plain circle with tick marks or as a single line through a circle indicating a single runway. The key is the shape itself communicates the physical layout of the facility.
What matters most for airspace awareness, however, is the color and fill of that symbol. Sectional charts use two primary colors for airport depictions:
- Blue airports have an operating control tower. A blue color means ATC is present and actively managing traffic, which also means the airport sits in Class B, Class C, or Class D airspace (depending on the tower's designation). Remote pilots must have prior authorization to fly within the associated controlled airspace.
- Magenta airports do not have an operating control tower. These may be Class E or Class G airspace airports. Many magenta airports still have associated airspace designations that affect drone operations, so color alone does not tell the whole story — the surrounding airspace rings must also be checked.
Controlled vs. Uncontrolled: Reading the Airspace Rings
Airport symbols on sectionals are accompanied by surrounding airspace depictions that are just as important as the symbol itself. For Class D airspace — the most common controlled airspace around towered general aviation airports — you will see a dashed blue circle around the airport. This ring typically extends about 4–5 nautical miles in radius (though the exact dimensions are published in the FAA Chart Supplement) and rises from the surface to an altitude shown in a blue box near the ring, expressed in hundreds of feet MSL.
For Class C airspace, look for two solid magenta circles (an inner core ring and an outer shelf ring) around the airport. Class C airspace typically consists of a core surface area with about a 5 nautical mile radius and an outer shelf area extending out to about 10 nautical miles from the primary airport, with different floor altitudes in the inner versus outer area. The altitudes are depicted in magenta fractions — for example, 40/SFC means the floor is the surface and the ceiling is 4,000 feet MSL, while 40/20 means the shelf exists between 2,000 and 4,000 feet MSL. All Class C airspace requires authorization for Part 107 operations.
For Class B airspace — surrounding the nation's busiest airports — solid blue lines form multiple rings and shelves, creating an upside-down wedding cake appearance on the chart. Floor and ceiling altitudes are shown in blue fractions in each segment. Class B is among the most restrictive airspace for drone pilots.
Many non-towered airports have a dashed magenta circle around them. This circle indicates Class E airspace that begins at the surface (a surface-based Class E designation). This is commonly found at airports that have instrument approaches but no control tower. Although there is no ATC tower, the surface-based Class E designation still requires LAANC authorization or a Part 107 waiver for drone operations at the surface level.
The Airport Data Block
Alongside every airport symbol on a sectional chart, you will find a data block — a cluster of text that provides critical operational information about that airport. Learning to decode each line of the data block is a core skill for the Part 107 test. Here is what each element means:
- Airport name: Printed in large text above or beside the symbol. Controlled (towered) airports use all-capital letters in blue; non-towered airports are also labeled but in magenta text.
- ATIS/ASOS/AWOS frequency: Automated weather broadcast frequencies are listed when available, helping pilots and drone operators assess local weather conditions.
- Tower or CTAF/UNICOM frequency: For towered airports, the tower frequency is shown. For non-towered airports, the Common Traffic Advisory Frequency (CTAF) or UNICOM frequency is listed with a circled C (for CTAF) notation.
- Field elevation: The airport's elevation above mean sea level (MSL) in feet is shown directly below the airport name. For example, 1234 means the field sits at 1,234 feet MSL. This matters for calculating density altitude and understanding AGL versus MSL altitudes for drone operations.
- Longest runway length: The length of the airport's longest runway is shown in hundreds of feet. For example, 35 means the longest runway is approximately 3,500 feet. This gives remote pilots context about the type of aircraft operations at the airport.
- Lighting: The letter L beside the runway length indicates the airport has runway lighting available. An asterisk before the L indicates the lighting is not available continuously (it operates only part-time or on request). The presence of a lighting notation only tells you lighting is available — it does not by itself mean night operations occur at that airport.
Traffic Pattern Altitude and Its Relevance to Drones
Standard traffic pattern altitude at most general aviation airports is 1,000 feet AGL above the airport elevation. Some larger aircraft use 1,500 feet AGL. Because Part 107 operations are limited to 400 feet AGL by default (or within 400 feet of a structure), remote pilots flying near airports must be especially aware that manned aircraft in the pattern are often directly above the legal drone ceiling. This is precisely why airspace authorization is required near airports — the risk of conflict with arriving and departing traffic is real even well below the drone's maximum altitude.
When you see an airport on the sectional, mentally picture a cylinder of active manned aircraft traffic rising from the runway surface up through 1,000 feet AGL (or higher), extending several miles in each direction of the traffic pattern. A drone operating at 300 feet AGL half a mile from the runway threshold may be directly beneath a turning aircraft on final approach.
Special Airport Notations
Sectionals also include several additional notations that affect drone operations specifically:
- Abandoned airports: Depicted with an X through the runway symbol. These are no longer operational but may still be surrounded by active airspace if the designation has not been formally cancelled.
- Seaplane bases: Shown with an anchor symbol inside the circle, indicating water operations.
- Heliports: Shown as a small circle with an H inside, often in blue (towered) or magenta (non-towered). Heliports generate their own airspace considerations.
- Military airports: Depicted with the standard symbol but with a shield or specific notation indicating military use. Drone pilots should be especially cautious near military fields due to potential restricted or prohibited area overlaps.
- Private airports: Labeled with Pvt next to the name, indicating the airport is not open to the public. The airspace above a private airport still exists and affects operations.
Key Numbers and Rules
- Blue airport symbol = operating control tower (Class B, C, or D airspace)
- Magenta airport symbol = no operating control tower
- Dashed blue circle = Class D surface airspace (typically 4–5 NM radius)
- Solid magenta circle(s) = Class C airspace (core ~5 NM radius, shelf out to ~10 NM)
- Solid blue lines = Class B airspace
- Dashed magenta circle = surface-based Class E airspace
- Standard traffic pattern altitude = 1,000 feet AGL (some airports 1,500 feet AGL)
- Part 107 altitude limit = 400 feet AGL (unless within 400 feet of a structure)
- Field elevation is listed in feet MSL directly in the data block
- Runway length shown in hundreds of feet (e.g., 35 = ~3,500 ft)
Common Test Traps
- Color confusion: Students sometimes assume a magenta airport is always uncontrolled. In reality, a magenta airport symbol means no tower, but the airport may still lie within Class E airspace that begins at the surface — requiring authorization for drone operations.
- Dashed vs. solid circles: A dashed blue circle means Class D; a dashed magenta circle means surface Class E. Mixing these up on the test is a classic error. Remember: blue = tower-related, magenta = non-tower but potentially controlled.
- Field elevation vs. AGL altitude: The data block shows elevation MSL, not AGL. A drone flying at 400 feet AGL at an airport with a field elevation of 800 feet MSL is at 1,200 feet MSL — a common calculation error on the knowledge test.
- Assuming no authorization is needed at non-towered airports: Many non-towered airports have surface-based Class E airspace (dashed magenta ring) that still requires Part 107 LAANC authorization or a waiver before operations at or near the surface.
- Ignoring the data block altitude numbers: The MSL ceiling/floor numbers beside airspace rings tell you exactly where controlled airspace begins and ends. A test question may describe an altitude that appears to be outside controlled airspace but falls within a shelf — always read the fractions carefully.