Understanding Controlled Airspace

When I’m instructing students, we usually spend an entire day devoted to understanding how to identify controlled airspace, what it is, and how to operate a UAS in it. It’s a big topic and I like to spend a lot of time on it because it represents a large part of the FAA Part 107 exam.

In this post, we’ll cover the different types of controlled airspace, how to recognize it, and how to fly a UAS in it safely and legally.

What is Controlled Airspace?

For the purposes of a UAS, controlled airspace is any airspace that requires prior authorization to fly in. While there are multiple varieties of controlled airspace, a few come to mind and they all have one thing in common: they’re located around airports.

  • Class B (that’s pronounced Bravo)
  • Class C (pronounced Charlie)
  • Class D (pronounced Delta)
  • Class E (pronounced Echo)

Pretty simple right?

Well, it can be. But it can also be kinda complicated as you’ll see later (I’m talking about you, Class E). The main thing you should know is Class B, C, D, and E airspace protects manned traffic as aircraft move into and out of these low level areas around airports.

Class B – Big, Blue, Busy

In the simplest terms, Class B airspace is the airspace surrounding the nation’s busiest airports. Think of major hubs like JFK in New York or LAX in Los Angeles. You’ll see DFW on the Part 107 exam. These are places where the skies are bustling with activity, and hence, the need for stricter regulations.

Why is it Blue?

If you’ve ever had the pleasure (or perhaps the slight confusion) of looking at a VFR sectional chart, you’ll notice that Class B airspace is outlined in solid blue lines. This isn’t just to make it look pretty on the map. The blue color serves as a quick visual cue for pilots to recognize and respect the boundaries of these high-traffic areas.

The Layers of Class B

Imagine an upside-down wedding cake.

That’s Class B for you.

It has multiple layers, each expanding outwards as you move further from the ground. The reason? To accommodate the large number of aircraft descending into or climbing out of major airports. The closer you get to the airport, the stricter the airspace becomes.

When looking at the sectional chart, you’ll see inverted fractions written in blue within each segment of the Class B airspace indicated the ceiling and the floor of the airspace within the lateral limited depicted on the chart. At the airport (like DFW, for instance), the inverted fraction would look like 110/SFC. That means the ceiling is 11,000 feet mean sea level (MSL) and the floor of the Class B is the surface. Notice you add two zeros to the number to get the actual number.

As you move away from the center of this airspace, the floor begins to climb and you’ll see numbers like 110/30, meaning the ceiling is still 11,000 feet MSL, but the floor is now higher at 3,000 feet MSL.

Operating a UAS in Class B

Now, for my drone enthusiasts, flying in Class B airspace isn’t a casual Sunday activity. Given the high volume of manned aircraft, it’s crucial to have prior authorization. And trust me, you don’t want to be “that person” who disrupts a commercial flight path. Always ensure you have the necessary permissions and stay updated with the FAA’s guidelines.

Class B is like the VIP section of the sky. It’s where the big players hang out, and it demands respect and understanding. Whether you’re piloting a manned aircraft or a drone, knowledge of this airspace is crucial. So, the next time you hear “Class B,” think “Big, Blue, Busy,” and remember the importance of flying safely and responsibly.

Class C – Congested

Class C airspace is usually located around regional airports that aren’t as busy as Class B, but still busy enough to need a control tower and radar services to help pilots navigate through the airspace while maintaining separation from other manned traffic.

On a sectional chart, you’ll identify it by its solid magenta lines. There are usually two solid magenta lines circling the airport – a center ring and an outer ring. While it’s not as complex looking as Class B, Class C airspace would like like an upside down wedding cake.

More like the groom’s cake though… not too fancy to distract from the bride’s cake (Class B).

Just like Class B, Class C airspace has a defined lateral boundary and a defined vertical boundary.

And just like Class B, the ceiling and floor of the Class C airspace is indicated by an inverted fraction within the lateral boundaries of that airspace.

If you look at Nashville Intl (BNA) airport, you’ll notice the ceiling is 6,000 feet MSL and the floor is the surface (SFC) nearest the airport (60/SFC), but as you move away from the airport into one of the other segmented areas, the ceiling remains at 6,000 feet MSL, but the floor increases to 1,800 feet MSL!

Those inverted fractions are pretty helpful.

Remember, Class C is controlled airspace and requires prior authorization before flying there.

Class D

Class D airspace is located around less busy airports, but often have flight schools associated with them and other training activities. The support some commercial flights, but usually regional or charter flights. You won’t normally see any of the larger airlines operating at these airport because they’re simply too small and can’t accommodate the requirements like TSA checkpoints.

Nevertheless, Class D is controlled airspace and usually has a control tower helping provide separation between manned aircraft operating within that space.

Class D airspace starts at the surface and has a defined lateral and vertical boundary. On a sectional charge you’ll identify Class D airspace as a dashed blue line.

Look inside the green circle I’ve drawn. The red arrow is pointing to the dashed blue line of the Class D airspace.

Unlike Class B and C, Class D doesn’t use inverted fractions to indicate the upper and lower limits of the airspace. Instead, you’ll only see the upper limit (ceiling) in a blue bracketed box within the dashed blue circle.

In the world of cakes, this one is pretty plain – a single cylinder with no layers.

But that doesn’t make Class D any less special as it too is controlled airspace and requires prior authorization before you can fly there.

A good example of Class D airspace is my home airport of HKS – Hawkins field, nestled below the Class C shelf of JAN – Jackson Intl.

Class E (the most complicated, difficult to understand airspace UAS pilots will typically face).

I like to tell my students that Class E airspace is like a blanket that covers the entire country – from sea to shining sea, northern border to southern boarder, and everywhere in between.

In face, if you’re reading this and you’re in the United States, Class E airspace is above you right now.

You can’t see it, but trust me. It’s there.

In fact, Class E airspace typically has a floor of 1,200 feet above ground (AGL) unless it dips down to 700 feet AGL around airports, or all the way to the surface around certain other airports.

But how do you know what the floor of the Class E airspace is, Nathan?

I’m glad you asked!

Class E with a Floor of 1,200 Feet AGL

As I mentioned above, Class E airspace usually has a floor of 1,200 feet AGL. On a VFR sectional chart, it’s hard to depict, but you can sometimes see it on the edges of the map – east and west coasts and north and south boarders. On a sectional chart, it’s indicated by a faded blue line.

Faded blue line = Class E airspace has a floor of 1,200 feet AGL.

Remember that unless you’re looking at the edge of the map, you won’t see Class E at 1,200 feet.

You just have to trust me!

Class E with a Floor of 700 Feet AGL

Sometimes, Class E dips down to 700 feet AGL – particularly around small community airports that have infrequent traffic.

You’ll know Class E at 700 feet by the faded magenta line around an airport or group of airports. Sometimes the faded magenta line is a circle, sometimes it’s a blob.

Hi Blob!

Class E with a Floor of the Surface

And then you have Class E that dips all the way down to the surface to provide protection for manned aircraft at airports that have an instrument approach.

You see, airports with an instrument approach allow instrument rated pilots to land their instrument rated aircraft even when the weather conditions and visibility aren’t very good. Instead of looking out the cockpit and seeing the runway, an instrument rated pilot flying an instrument rated aircraft can navigate to the airport using…. (you guessed it)… instruments.

Surface Class E airspace around these airports are depicted on a VFR sectional chart as a dashed magenta line.

UAS pilots are not permitted to fly within the lateral boundaries of a surface Class E airspace without receiving prior authorization from ATC. That’s because just like Class B, C, and D, Surface Class E airspace is controlled airspace.

How Do I Operate My UAS in Controlled Airspace?

Great question!

There are essentially two ways – you’ll like the first one.

The second one? Notsomuch

  1. LAANC – Low Altitude Authorization and Notification Capability, is an initiative by the Federal Aviation Administration (FAA) in collaboration with the drone industry. It’s designed to facilitate and expedite the approval process for drone operators who wish to fly in controlled airspace, especially near airports. In practice, LAANC provide INSTANT approval for drone operations within the lateral boundaries of controlled airspace as long as you don’t request flights above the approved altitudes published in the UAS Facility Maps (on the FAA website).
  2. For airspace authorizations that are above the published altitudes (say the FAA published 100 feet, but you need 125 feet), you’ll have to go through the manual process of requesting an airspace authorization and that takes time… a lot of time. Like up to 90 days. That can be done through the FAA Drone Zone website and is a pretty straightforward processes. You just have to be able to justify the need to fly and have a good plan on how you’ll do it safely. If the FAA is convinced you can fly there safely at the requested altitude, they’ll grant you the authorization along with some additional requirements.

Confused Yet?

Hopefully, that clears up some of the confusion around operating drones within controlled airspace. This is part of a larger series of post that we’ll publish on the topic, so don’t be dismayed if you don’t fully grasp controlled airspace. It takes most people a little while to understand it, and many long time pilot still have trouble.

But if you ever forget, look at the Section Chart Legend on the side of a VFR sectional chart, or in the UAS Testing Supplement if you’re studying for your Part 107 exam. It’s all there!

The main takeaway is this: UAS pilot are required to receive authorization from ATC prior to operating their UAS within controlled airspace.

If any of this sounds too confusing to you and you would like some one-on-one help, we offer a few options that you might be interested in. Let us know if we can help!

Happy flying!

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