What is the difference between controlled and uncontrolled airspace on a sectional chart?

Controlled airspace is airspace where air traffic control services are provided, including Classes A, B, C, D, and E, each depicted on sectional charts with specific colors and symbols — for example, Class B airspace appears as solid blue lines and Class C as solid magenta lines. Uncontrolled airspace, or Class G, is the airspace that remains after all controlled airspace has been defined and is not explicitly outlined on sectional charts; you identify it by recognizing where controlled airspace ends. Understanding this distinction is essential for Part 107 remote pilots because operating in controlled airspace at or above 400 feet AGL generally requires FAA authorization through LAANC or a DroneZone waiver.

How do you identify Class E airspace on a sectional chart?

Class E airspace is depicted on sectional charts in several ways depending on its configuration: a dashed magenta line indicates Class E airspace that extends down to the surface, while a fading magenta vignette (shaded area) marks where Class E begins at 700 feet AGL rather than the standard 1,200 feet AGL floor. A fading blue vignette indicates Class E beginning at 1,200 feet AGL in certain areas. Because Class E is controlled airspace, Part 107 remote pilots must obtain authorization before operating within it if it extends to the surface around an airport.

Why does it matter whether airspace is controlled or uncontrolled for Part 107 drone operations?

Under 14 CFR Part 107, remote pilots must obtain prior authorization from the FAA before flying a small unmanned aircraft in controlled airspace, which includes Classes B, C, D, and surface-level Class E. In uncontrolled Class G airspace, no ATC authorization is required, though all other Part 107 rules still apply. Misidentifying airspace type on a sectional chart and flying in controlled airspace without authorization is a regulatory violation that can result in civil penalties, making accurate sectional chart reading a core competency tested on the FAA Unmanned Aircraft General — Small UAS Rating Knowledge Test.

Controlled vs Uncontrolled Airspace Identification on Sectional Charts

One of the most essential skills for any FAA Part 107 remote pilot is the ability to look at a sectional aeronautical chart and instantly recognize what type of airspace lies above a proposed drone flight location. The consequences of operating in the wrong airspace without authorization can include civil penalties and certificate actions — so reading sectional charts correctly is not just an exam requirement, it is a genuine safety and legal obligation. This article walks you through exactly how controlled and uncontrolled airspace appears on sectional charts, what the boundaries mean in practice, and how to apply that knowledge both on the Part 107 knowledge test and in the field.

The National Airspace System (NAS) is divided into classes, each with its own entry requirements, communication requirements, and operational rules. For remote pilots, the most critical distinction is between controlled airspace (Classes A, B, C, D, and E) — where specific rules and, in many cases, explicit FAA authorization are required — and uncontrolled airspace (Class G) — where no ATC clearance or authorization is needed to fly a small UAS under Part 107, provided all other rules are followed.

The Airspace Classes at a Glance

Before diving into chart symbology, it helps to understand what each class represents operationally. Class A airspace covers 18,000 feet MSL up to FL600 and is not relevant to drone operations since Part 107 limits UAS to a maximum of 400 feet AGL (or within 400 feet of a structure). Class B airspace surrounds the nation's busiest airports and resembles an upside-down wedding cake in three dimensions. Class C airspace surrounds airports with an operational radar approach control. Class D airspace typically surrounds airports with an operational control tower. Class E airspace is the most prevalent form of controlled airspace and fills most of the airspace between the surface and 18,000 feet MSL that is not otherwise classified. Class G airspace is uncontrolled and typically extends from the surface up to 700 or 1,200 feet AGL, depending on location, before transitioning into Class E.

How Each Airspace Class Appears on a Sectional Chart

Class B Airspace

Class B airspace is depicted on sectional charts with solid blue lines that form concentric rings around major hub airports. The rings represent the lateral boundaries of each layer of the wedding-cake structure. Inside each ring segment, a fraction is printed — for example, 100/SFC — meaning the ceiling of that segment is 10,000 feet MSL and the floor is the surface. Alternatively, you might see 100/50, meaning the ceiling is 10,000 and the floor is 5,000 feet MSL. The primary airport at the center is labeled, and the entire Class B area is shaded light blue on the chart. For Part 107 remote pilots, operating in Class B without a valid LAANC authorization or FAA waiver is prohibited regardless of altitude.

Class C Airspace

Class C airspace is shown with solid magenta lines forming two concentric circles around the primary airport. The inner circle typically has a radius of 5 nautical miles and extends from the surface to 4,000 feet AGL above the airport elevation. The outer ring typically extends from 5 to 10 nautical miles and starts at 1,200 feet AGL. Each ring segment carries a ceiling/floor fraction in the same format used for Class B. A key chart clue: Class C uses magenta, while Class B uses blue. Remote pilots must obtain authorization before flying a drone in Class C airspace.

Class D Airspace

Class D airspace is depicted with a dashed blue line forming a rough circle (often irregular to account for terrain and procedures) around airports that have an operational control tower. The ceiling of Class D airspace is typically 2,500 feet AGL above the airport elevation, and this value is shown in a small box on the chart in hundreds of feet MSL — for example, [25] means the ceiling is 2,500 feet MSL. Class D airspace exists only when the control tower is operating; outside tower hours it typically reverts to Class E or G. Remote pilots require authorization to fly within Class D.

Class E Airspace

Class E is the most complex airspace to identify because it manifests in several different forms on a sectional chart. Understanding each depiction is critical for the Part 107 exam.

Class E surface area: Depicted by a dashed magenta line around an airport. This designates Class E airspace that begins at the surface, typically associated with instrument approaches at airports without a control tower. Remote pilots must obtain authorization to fly here.
Class E from 700 feet AGL: Shown as a shaded (fuzzy) magenta vignette on the chart — the magenta color is dense at the edge and fades outward. Inside this shaded area, Class E begins at 700 feet AGL. Below 700 feet AGL, the airspace is Class G — meaning a remote pilot operating below 400 feet AGL is in uncontrolled airspace and needs no authorization, even inside the magenta shading.
Class E from 1,200 feet AGL: Shown as a shaded (fuzzy) blue vignette. Inside this blue-shaded boundary, Class E begins at 1,200 feet AGL. Below that, Class G airspace exists.
Class E at higher altitudes: In some areas, Class E begins at 14,500 feet MSL or other altitudes as noted on the chart, generally not relevant to drone operations.

Class G Airspace

Class G airspace does not have its own dedicated symbol — it is simply the airspace that remains wherever no other class has been designated. Practically speaking, wherever you see the magenta shading (700-foot floor) or blue shading (1,200-foot floor) on a sectional chart, the airspace below that floor is Class G. In remote, rural areas far from airports and instrument procedures, Class G can extend from the surface all the way up to 14,500 feet MSL. Under Part 107, no authorization is needed to fly in Class G, but the 400-foot AGL ceiling and all other Part 107 rules still apply.

Why This Matters for Part 107 Remote Pilots

Under 14 CFR Part 107.41, no person may operate a small unmanned aircraft in Class B, C, or D airspace, or within the lateral boundaries of the surface area of Class E airspace designated for an airport, without prior authorization from ATC. The primary authorization tool is LAANC (Low Altitude Authorization and Notification Capability), an automated system that grants near-real-time authorization up to approved altitude ceilings at participating airports. Where LAANC is not available, pilots must apply through the FAA DroneZone portal. Operating in controlled airspace without authorization violates federal regulations even if the flight is at a low altitude and poses no apparent conflict with manned aircraft.

The good news for remote pilots is that the vast majority of the continental United States below 400 feet AGL is Class G airspace, particularly in rural areas. Reading the sectional correctly lets you quickly determine whether a site is authorization-free or requires prior approval — saving time and preventing regulatory violations.

Key Numbers and Rules

Class B boundary: Solid blue lines; authorization required for UAS.
Class C boundary: Solid magenta lines (two circles); authorization required for UAS.
Class D boundary: Dashed blue lines; authorization required; check NOTAM for tower hours.
Class E surface area: Dashed magenta lines; authorization required for UAS.
Class E at 700 AGL: Shaded/fuzzy magenta vignette; below 700 feet AGL is Class G — no authorization required.
Class E at 1,200 AGL: Shaded/fuzzy blue vignette; below 1,200 feet AGL is Class G — no authorization required.
Part 107 altitude ceiling: 400 feet AGL (or up to 400 feet above a structure).
Authorization tool: LAANC or FAA DroneZone (14 CFR 107.41).

Memory Aid

A widely used mnemonic to remember which airspace classes are controlled is "A B C D E" — All five are controlled. Class G is the only uncontrolled class, and G can stand for "Go freely" (with all other rules still in effect). For chart colors specifically, remember: Blue is B, Magenta is More — Class B uses blue lines, and magenta is used for Class C (solid magenta), Class E surface areas (dashed magenta), and the 700-foot Class E floor (shaded magenta). When you see magenta on a sectional, think carefully about what type of line or shading it is, because the difference between dashed, solid, and faded magenta determines whether you need authorization at the surface level.

Common Test Traps

Confusing the magenta shading with a surface authorization requirement: The fuzzy/shaded magenta vignette means Class E begins at 700 feet AGL — NOT at the surface. Below 700 feet AGL in a shaded magenta area is Class G, so no authorization is needed for a typical drone flight. The exam loves to test this distinction.
Mistaking dashed blue for dashed magenta: Dashed blue = Class D (controlled, tower airport). Dashed magenta = Class E surface area (controlled, instrument procedures). They look similar in a hurry — check the color carefully.
Assuming Class D is always active: Class D exists only when the control tower is operational. During hours the tower is closed, the airspace may revert to Class E or G. Always check NOTAMs and the Chart Supplement for tower hours before assuming authorization is required.
Ignoring ceiling/floor fractions on Class B and C segments: The numbers inside the rings tell you the floor of each segment. A drone flying at 350 feet AGL beneath a Class B segment whose floor is listed as 3,000 MSL may actually be in Class G or E — not Class B. You must check the floor of each individual segment, not just whether you are inside the outer boundary.
Thinking Class G means no rules apply: Class G is uncontrolled from an ATC perspective, but all Part 107 operational rules — altitude limits, daylight operations, see-and-avoid, etc. — still apply in full. Uncontrolled does not mean unregulated.