Understanding the National Airspace System
Before diving into the individual airspace classes over the next several lessons, this lesson builds the big-picture map they all fit into: the National Airspace System (NAS) ? the entire network of controlled and uncontrolled airspace, airports, and air traffic services covering the United States. Understanding why the system is organized the way it is makes the individual classes far easier to remember than treating each one as an isolated fact to memorize.
What the National Airspace System is
The National Airspace System is the FAA's term for the entire integrated network of US airspace, airports, air traffic control facilities, navigation aids, and the procedures that tie them all together. It exists to let an enormous volume of extremely varied traffic ? airliners, general aviation aircraft, military jets, helicopters, and now small unmanned aircraft ? share the same sky safely. Airspace classification is the tool the FAA uses to match the level of air traffic control service, communication requirements, and equipment requirements to the actual traffic complexity and risk found at each location.
Two fundamental categories: controlled and uncontrolled
Every one of the six US airspace classes falls into one of two broad categories. Controlled airspace (Classes A, B, C, D, and E) is airspace within which air traffic control provides some level of service to aircraft operating under instrument flight rules, and in some cases to aircraft operating under visual flight rules as well. Uncontrolled airspace (Class G) is airspace where ATC does not provide separation services ? pilots are responsible for their own separation from other traffic through see-and-avoid.
For Part 107 purposes, this distinction matters directly: 14 CFR 107.41 requires prior ATC authorization before operating in Class B, C, or D airspace, or within the lateral boundaries of a Class E surface area designated for an airport ? but no such authorization requirement exists for Class G, since there's no ATC facility providing the service a request would even be routed to.
Why six classes, not one uniform system
The busiest, most complex airports need the most protective airspace and the strictest equipment and communication requirements ? that's Class B. Airports with somewhat less traffic but still meaningful complexity get Class C or Class D, scaled down accordingly. Away from airports entirely, the airspace transitions to Class E (general controlled airspace, mostly relevant for instrument flight separation at higher altitudes) and eventually Class G (uncontrolled) at the lowest altitudes in less busy areas. Class A sits at the very top of the system, reserved for high-altitude traffic operating under instrument flight rules only. Each class exists because a one-size-fits-all set of rules would either over-restrict quiet rural airspace or under-protect the airspace around the nation's busiest hubs.
Real-world scenario: the first question on every job
A remote pilot accepts a new inspection job at an address they've never flown near before. Before anything else ? before checking weather, before planning the flight path ? the very first practical question is: what airspace class covers this location? The answer determines whether the flight can launch immediately (Class G, no authorization needed) or whether an authorization request needs to be submitted first through LAANC or DroneZone (Class B, C, D, or a Class E surface area), which can take anywhere from seconds to much longer depending on the specific airspace and altitude requested ? covered fully in Lessons K and L.
A system-wide cross-section of how the six airspace classes relate to each other by altitude and location.
View Larger| Class | Category | Typical location | Part 107 authorization required? |
|---|---|---|---|
| A | Controlled | 18,000 ft MSL to FL600, nationwide | Not applicable ? sUAS cannot operate there |
| B | Controlled | Around the busiest major airports | Yes |
| C | Controlled | Around airports with radar approach control | Yes |
| D | Controlled | Around smaller towered airports | Yes |
| E | Controlled | General controlled airspace; surface areas at some airports | Only within a designated surface area |
| G | Uncontrolled | Below controlled airspace, away from busy airports | No |
Determining what airspace covers a new job site
Do this before planning any other part of a new mission.
Check a current sectional chart or an FAA-approved airspace app for the location
Module 4 covers reading sectional charts in depth; for now, note whether the location falls near a major airport, a smaller towered field, or open rural terrain.
Identify the airspace class and its floor/ceiling at that location
The same physical spot can have different airspace classes depending on altitude ? a location under Class B's shelf might be Class G right at the surface.
Determine whether 107.41 authorization is required
Class B, C, D, or a Class E surface area means an authorization request comes before anything else in mission planning.
Is there a Class F airspace in the United States?
No. Class F exists in the ICAO airspace classification system used internationally, but it is not used domestically in the conterminous United States ? only Classes A, B, C, D, E, and G apply.
Does every location have only one applicable airspace class?
A single geographic point can be covered by different airspace classes depending on altitude ? for example, Class G at the surface transitioning to Class E at a higher floor, and eventually Class A far above that.
Does 107.41 require authorization for Class A airspace?
Class A airspace begins at 18,000 feet MSL, far above the 400-foot AGL ceiling standard Part 107 operations are limited to, so the question is effectively moot ? sUAS operations don't reach Class A under normal circumstances.
Test Your Knowledge
Answer the questions below to check your understanding. Every answer can be found in the lesson above.