Lesson 10: Introduction to Airspace Classes: Class B, C, and D

Welcome back, future pilot! Now that we've learned about controlled and uncontrolled airspace and towered airports, let's dive deeper into the sky! Today, we’ll explore classes of airspace: those circles you saw on sectional charts last week. Just like there are big and small cities, the sky is divided into different classes of airspace, each with its own rules and purposes. Airspace is categorized into different classes to help manage and organize the movement of aircraft. In the National Airspace System, there are 6 classes of airspace, and they are categorized from A-G. We skip F, because no one likes F’s! Not even pilots. Class A is the most restrictive, and Class G is the least restrictive. Class E airspace is the most common type of airspace and is found throughout the country.

Today, we’ll start by learning about Class B, C, and D airspaces. Next lesson, we’ll finalize it with Class G and E. 

Hey! But why aren’t we covering Class A?

Class A Airspace is just for airplanes. It starts at about 18,000 feet MSL and is basically the entire sky! Class A is so high up, it’s not even marked on a sectional chart.

Do you remember what MSL stands for? 

MSL means Mean Sea Level. It’s the height above the sea. Don’t forget MSL and AGL! They're going to come up all the time! AGL means Above Ground Level. It’s the height above the actual ground. Small drone pilots will never, ever fly in Class A airspace. Plus, our drones won’t even go that far. So let’s stick Class B - E, which is what we need to worry about. 

Airspace Alphabet 

The closer we get in the alphabet to the letter A, the more nervous pilots get! They get bigger and have way more rules that pilots need to follow.

Here’s a tip! Because Class B, C, and D are in controlled airspace, you’re not allowed to fly in them – unless you have a waiver from The FAA. Remember, lots of airplanes flying are around in these airspaces, with stressed out Air Traffic Controllers helping them.   

Get ready to explore Class B, C, and D airspace! We'll learn where they are, their specific rules, their unique shapes, and how to read them on sectional charts. 

What’s Up Ahead

✓ Class B is the biggest and busiest airspace around big airports.
✓ Class C is found at smaller but busy airports.
✓ Class D is the smallest class, found around the smallest towered airports. 

Understanding these classes will help you navigate the skies safely and confidently!

On maps, these airspaces look like flat circles. But in real life, bigger airspaces are shaped like upside down wedding cakes. 

It’s a bit abstract, but it makes sense, right? Because airspace is in the sky, it’s hard to imagine! We have to use a little imagination. 

Floors and Ceilings

Before we define each class, let’s understand a key concept we’ll encounter a lot: ‘floors and ceilings’ of airspace. They help define the boundaries of airspace, so we know exactly where they start and end (especially when they have funky shapes). In aviation, floors and ceilings of airspace define the height of each airspace class. It’s crucial for pilots so they can navigate safely. The floor of airspace is where it starts – at the bottom. And the ceiling is where the airspace ends – at the top. Just like a room! 

How are floors and ceilings of airspace shown on charts? 

The top number represents the top of the airspace, or the ceiling! And the bottom one represents… can you guess? Right! The bottom, or floor, of the airspace - where it starts! 

What do the numbers represent? 

The top number represents the ceiling of the area in hundreds of feet. The and the lower number represents the floor, also in hundreds of feet. All this means: add two zeros to the end of each number! 

So 110 would become 110 + 00 = 11,000 feet and 30 would become 30 + 00 = 3,000 feet

This means that this part of Dallas Airport starts at 3,000 feet MSL and ends at 11,000 feet MSL! Pretty big, but so is Dallas. 

Can you calculate the floor and ceiling of this part of the airspace around San Francisco International Airport? 

Ceiling: 10,000 feet MSL and Floor: 2,100 feet MSL

Heads up! Big airspaces have multiple layers. So each layer will have a floor and ceiling numbers around them, since each layer has a different floor or ceiling. For example, if we think of this top layer of the wedding cake, it’s not going to start at the floor! But at that height in the sky. 

Wow! That was impressive! Now, let’s end this section by clarifying a few more things about floors and ceilings. Most numbers on sectional charts are automatically measured in MSL! That includes floors and ceilings. Sea level is better to measure from. If a number has (parenthesis) around it on a chart, it’s measured in AGL. Otherwise, it’s always in MSL! 

If you ever encounter this word SFC instead of a number, SFC is short for ‘Surface.’ All that just means is the airspace starts at the surface of the actual floor, or the ground!

And another tip! Class D is the only class that’s just written as one number instead of two. That’s because Class D always starts at the surface. It doesn’t have any layers, and it doesn’t float in the air. So we know it always starts at the floor - we don’t have to say it. 

Class D shows the ceiling (height) of its airspace as only one number in brackets! It only shows the ceiling - not the floor. The floor is always the surface anyways. Still add two zeros, though!  Class D just says 32 in special brackets.

Breaking Down Sectional Charts

And how pilots read them

We just talked about how to read floors and ceilings of airspace. Now, let’s define Class B, C, and D airspace! Then, we’ll look at how to read them on maps. Airports in Class D, B, and C always have Control Towers. So, these classes are always in Controlled Airspace. 

To fly drones in controlled airspace, you need a waiver approved by those cranky Air Traffic Controllers. Here’s the official graphic from the FAA. 

Class D

Let’s start with the smallest airspace, Class D! Pilots call it ‘Class Delta’ Airspace. Remember: Class D = Delta 

Where is Class D? You can usually find Class D Airspace usually around really small or regional airports that don’t fly big planes. This Class D airport is an hour away from Manhattan! It’s shaped like a cylinder around an airport! Class D is the only class of airspace without layers because it’s so smol. It’s just one shape. Where does Class D start and end? Now, let’s look at the usual size of Class D airspace.  

Where does Class D Airspace start?

Class D Airspace starts from the Surface (SFC)  up to 2,500 feet above the airport! It extends out to a radius of 4 miles of the Class D airport. Class D Airspace starts at The Surface and goes all the way up to 2,500 feet MSL above the airport.  

Pop Quiz! What’s the floor and ceiling of this airspace? 

Ceiling: 2,500 feet MSL
Floor: The Surface

Remember, ‘Surface’ just means it starts on the actual ground, no special height. It’s literally ‘the floor!’ Also Remember: Because Class D only has one layer, it’s always on the floor. Charts don’t write ‘SFC’ below it. On Sectional Charts, Class D is just one number (the ceiling) in brackets. Remember, ‘Surface’ (SFC) just means it starts on the actual ground. It’s literally ‘the floor!’ 

Great Work! Class D has special rules that the other classes don’t, because it’s so small. Let’s explore those rules! 

Does D have Control Towers? 

Yes! Class D Airports have Control Towers. But they might not be working at certain times of the day. Air Traffic Controllers at Class D airports don’t work 24/7 around the clock. Just like places close earlier in smaller cities, airports are the same with control towers. ATC wants to go home, and it’s not too busy. 

When Control Towers Are On  

When the Control Towers are working, you have to follow the normal Class D rules in that airspace. That means: you can’t fly there without a waiver!

When Control Towers Are Off  

When the Control Towers aren’t working and ATC goes home, Class D Airspace becomes Uncontrolled! Then, pilots have to follow different rules. When the towers not operating, Class E or G* rules will apply, and you don’t need a waiver to fly there! Unless it’s a special type of Class E airspace. Don’t worry, we’ll learn about Class E and G in the next session!

If you plan to fly in or around Class D airspace, make sure you check out to see if the Control Towers are operating or not. If they are, it’s illegal to fly there. 

Awesome job! You’re doing great. This is hard stuff! Now let’s recap Class D. 

Class D (Delta) is the smallest airspace. Class D usually surrounds small or regional airports in small towns or in rural areas. It starts at the floor (the surface) and goes up to 2,500 feet above the airport.  Class D Airports Have Towers. When they’re on and operating, normal Controlled Airspace rules apply and you’d need a waiver. When they’re off, Class D turns into other airspace classes, and different rules apply. You don’t need a waiver at those times. 

•  Airspace for small airports and small cities 

• Has control towers that don’t operate 24/7

• Turns into Class G or E when towers don’t

• Starts at the SFC and goes up to 2,500 ft. MSL

• It’s just smol! Only one layer - a cylinder. 

Nice Work! Does this make sense? So many rules!! 

Now, let’s cover Class D’s big brother: Class C. 

Class C 

Pilots call Class C Airspace ‘Class Charlie’. Remember: Class C = Charlie

Where can I find Class C Airspace? You can usually find Class C Airspace usually around medium-sized airports in medium-sized cities. Can you think of any medium-sized cities? Great! Think Palm Beach in Florida, San Antonio in Texas, or Nashville in Tennessee. 

What shape does Class C have? It’s shaped like an upside-down wedding cake with two layers.  

How big is Class C? Now, let’s look at the usual size of Class C airspace. Class C Airspace generally starts from the Surface (SFC) up to 4,000 ft. (measured in MSL) above the airport.

Where does Class C Airspace start? Class C Airspace starts at The Surface and goes all the way up to 4,000 feet MSL above the airport. And, how would this be written on a sectional chart? Type your guess in the chat!

Does C have Control Towers? Yes! Class C Airports do have Control Towers. They are always on and operating 24/7. That means you can never fly there without a waiver. Class C Airspace is around medium-sized airports in medium-sized cities. Class C Airspace starts at the Surface and goes up to 4,000 feet above the airport. Class C Airports have Control Towers that are always on, so it’s illegal to fly there without special approval.  

Phew! Great work. Next, let’s cover the last class of airspace for today: Class B.  

Class B 

Pilots call Class C Airspace ‘Class Bravo’. We can think of B as in Big. 

These airports have made it big time in the big city.  You can find them in the busiest airports at the biggest cities flying the biggest airplanes in the country. Can you think of any big cities? Nice! Just like Los Angeles, New York, and Denver. Think JFK, LAX, and DEN. These airports must have control towers.

Where does Class B Airspace start? Class B Airspace starts from the Surface (SFC)  up to 10,000 feet (measured in MSL) above the airport!

Class B are around the biggest  and busiest airports in the biggest, busiest cities. They hustle and bustle! Class B airspace has multiple layers and is shaped like an upside-down wedding cake. Class B airspace starts at the Surface and goes up to 10,000 feet above the airport!     Class B Airports have Control Towers that are always on, so it’s illegal to fly there without special approval. It’s in Controlled Airspace! Don’t get arrested. 

Of course, now that we know about classes, the next thing we need to know how to do is to identify them on maps.

That way, we can see where they are, and if we’re flying near or inside of any! 

Let’s learn how to identify Class B, C, and D on Sectional Charts. 

• Delta is shown as dashed blue lines. Class D is shown as dashed blue lines and one circle   

• Charlie is shown as solid magenta lines. Class C is shown as solid magenta lines in 2 layers 

• Bravo is shown as solid blue lines. Class B is shown as solid blue lines in many circles Class B is Big. Class B does not play. 

It’s unfortunate that they’re not the prettiest colors, and they’re always used for most icons. But, it’s what we got. We can work with it! 

Remember the legend? If you ever forget what specific airspace circles look like, don’t panic! They’re on the Legend. And legends come with the test. Legendary! One more thing about Legends. We’ll hand this part over to our Legendary Remote Pilot in Command, who’ll guide us through a super helpful tip you can always access. 

Awesome! Next up, we’ll learn about the last thing you need to know about Sectional Charts – and it will make your life easier as a drone pilot! 

So let’s talk about the border of a sectional chart. 

Basically, instead of having to remember all the symbols, most of them are shown at the corner of a chart – just like the legend, but more detailed and specific to the area! There are about 50 Sectional Chart maps that cover the United States! Each one is named after a city on the map and the charts are updated every few months with the latest information from the FAA. Every chart of a big area has a border, which has super helpful information –  like when the last update was, any warnings, the elevation, and the controlling agencies to contact. And each one has a version of the legend, showing you what the icons mean!  

For Educators: Optional wrap-up activities, games, quizzes, and temperature checks can go here, time-permitting. 

The Borders of Sectional Charts are extremely handy. Let’s see if you can find one yourself, in any part of the country! 

• Step 1: Go to SkyVector and choose an area you’ve never been to. 

• Step 2: Next, scroll all the way to the side to see if you can find the border. 

• Step 3: Once you’re done, type the city’s name in the chat! 

Did you know there are more maps to use?  

SkyVector shows us Sectional Charts! But that’s not the only kind of map that pilots use. 

VFR   

You’ll see this term ‘VFR’ a lot. It stands for Visual Flight Rules!    

It's a way for pilots to fly their airplanes by looking outside and using their eyes to navigate, rather than relying only on instruments inside the airplane. 

VFR vs. IFR     

When pilots in the sky fly planes so high up they can’t use their eyesight to stay safe, they rely on instruments, and IFR, which means Instrument Flight Rules. Luckily, Drone Pilots only need to know about VFR! 

Pilots flying manned aircraft rely both on VFR and IFR, because when they are flying all the way up in clouds or at night, they can’t use their vision as a reference to fly. They use special instruments instead that can detect their altitude and speed. 

VFR Maps

Did you know that you can access VFR maps just like you can access Sectional Charts in Sky Vector? Let’s check out VFR Map.com. VFR maps let you zoom in more and click on an airport to find out specific information about it! It doesn't have the border of a sectional chart, but it does have airport information (which we’ll cover a bit later in this class). And here’s a tip! Since we talked about Class B, C, and D airspace, which kind of airport would you want to find airport information about? Nice! That would be Class D, because the control towers stop working at certain times, and then turn into other airspace. If you click on an airport in a VFR Map, it will tell you what class of airspace that airport is in, and what time they’re open. 

Great work! I see you’re all a few steps closer to becoming a certified drone pilot.