It’s easy to look up to the sky and see a bunch of nothing. I’m always in wonder when there are lots of unusual clouds because it gives great dimension to an otherwise endless blue void. On the ground, we draw imaginary lines all over the land, making states, counties, cities, and a multitude of other borders. In the air, similar lines are drawn, creating different segments of airspace, but it’s a lot more challenging to put signs up in the air showing the boundaries – they keep falling every time one is put up. As a result, we must rely on maps to tell us where the airspace is, but visualizing the airspace makes it a lot easier to understand. Whether you fly airplanes or drones, understanding where the different airspace is and what it means is critical. There are lots of nuances and exceptions to basic airspace rules, but let’s break down the basics for a good overview of the concept.

 

Controlled Airspace
Airspace is generally classified by how busy the traffic through it is. The busier the airspace, the more rules exist about flying in it. Rules such as whether two way radio communication or special equipment like a transponder is needed to enter. There are also various rules about the visibility and distance from clouds that pilots flying visually must follow. Controlled airspace is labeled as Class A, B, C, D, or E. Think of airspace as being laid out either in layers or cans. Some airspace is a layer, from one altitude up to another altitude, anywhere on the map. Other airspace is like a can – a cylinder of air with a radius around an airport and a certain height up from the ground. A note about altitudes: As we look at charts, keep in mind that altitudes printed on the chart are Mean Sea Level (MSL) altitudes.  This is the height above sea level – basically, what the altimeter will show.  You’ll find the altitudes printed in hundreds of feet (3300 feet is printed as 33).  The only altitude discussed in this that is not in MSL is Class G, which is Above Ground Level (AGL).  Let’s look at each class of airspace.

Layers of airspace are labeled in hundreds of feet.  Look for something like these layers of Class C airspace that are from (left) 1400 MSL to 4200 MSL and (right) the surface to 4200 MSL.

 

Class A
This airspace is a layer that exists from 18,000 feet up to 60,000 feet and is not charted on maps. For Class A, I think “A for airliners,” because it’s the layer containing many airline flights, and only higher performance airplanes with cabin pressurization or oxygen can get there. It’s the highway of the sky and requires an instrument flight plan and Air Traffic Control (ATC) clearance to fly there.

Class A airspace is a pretty straightforward layer from 18000 MSL to 60,000 MSL.

 

Class B, C, and D
These three types of airspace look like a cylinder and surround airports. Class B is around the nations busiest airports, like Atlanta. Class C is slightly less busy, like Nashville. Class D is less busy and are usually mostly general aviation airports, like Athens, Georgia. All of these start at the surface of the earth and extend up to a height marked on the sectional chart. Class D is a single cylinder of airspace, but you’ll see multiple cylinders of airspace stacked in class B and C – like a can on top of a smaller can, or an upside down wedding cake. How do you know the airspace on the map? By the color of the lines. Solid blue rings are the Class B boundaries, solid magenta for the Class C, and a dashed blue for Class D. Drone pilots can’t fly in any of this airspace without Air Traffic Control authorization.

This Class C airspace around Nashville has three different segments.  The core (inner magenta ring) starts from the ground/surface (SFC) and extends up to 4600 MSL (the 46).  The outer ring has two segments.  The left segment starts at 2400 MSL (the 24) and extends up to 4600 (the 46). The right segment starts at 2100 MSL (the 21) and extends up to 2400 MSL (the 24).  Its like an upside down wedding cake that tops out at 2400 MSL.

While the Class B airspace around Atlanta is very complicated, you can see that it is a big funnel-shaped area that all tops out at 12,500 feet (the 125 in hundreds of feet).  The core of the airspace begins at the surface (SFC) but the outer areas begin a layer at 2500 (the 25s) or 3000 (the 30s) feet and out to the layers that begin at 5000, 6000 and 7000 feet (the 50s, 60s, and 70s).  Whats underneath those layers that don’t start at the surface?  Class G up to 1200 feet AGL and then class E (read on to understand).

 

Class G – Uncontrolled Airspace
Woah, uncontrolled and out of control! Well, not really. For Class G, I think “G for ground.” This is a layer that starts at the ground and generally goes up to 1200 feet above the ground (AGL).  There are a few charted areas of class G that goes up beyond that, usually in mountainous regions, but don’t sweat that for now – just know it’s the airspace near the ground.  It’s called “uncontrolled” because it’s not serviced by air traffic control. You’re on your own, kid.  This is the only airspace that drones are allowed to fly in without special Air Traffic Control permission or an FAA waiver.  Really, the key to staying IN class G airspace as a drone operator is knowing the other airspace to stay OUT of.

Class G hangs out near the ground and countours the land up to 1200 feet above it.

 

Class E
Why did I go out of order? Because I like to think of “E for everywhere else,” because that’s what Class E essentially is. You’ll find it everywhere else we didn’t just define. It’s the filler airspace that start above the G near the ground and outside of the B, C and D airspace cylinders that surround airports. One thing that you’ll see commonly on the map is magenta bands around some airports. The outside of the band has a hard edge, and the inside of the band faded. In this ring, the class E airspace begins at 700 feet AGL instead of the usual 1200 feet AGL. I think of these rings like little bowls of class E airspace that pull the floor of Class E from 1200 down to 700 feet above the ground. In some cases, a dashed magenta area will be an area of Class E that is pulled from its usual 1200 foot start all the way to the surface.

Notice the magenta ring covering most of the picture.  Outside of that band, the class E airspace starts at 1200 feet AGL.  Inside of it is a “bowl” of class E that drops down, beginning at 700 AGL.  While Athens is surrounded by the dashed blue lines of class D up to 3300 MSL (indicated by the 33 in brackets), notice the dashed magenta to the right of the class D.  That’s a section where the class E begins at the surface, essentially connecting to the class E bowl at 700 feet above it.  This is done for the approaches that exist into the airport.

 

Put It All Together
Think of airspace like this. From the ground up to the first 1200 feet is class G. Once you get above that, you are in Class E all the way up, except the layer of class A from 18,000 to 60,000 feet. Once you get near an airport, you will likely find either class B, C, or D surrounding it like a can up to a certain height, shown on the map. It’s really that simple. Sure, there are some exceptions. There are no fly zones for airplanes and drones alike. Some airports are surrounded by class E to the surface. There are places where Class G goes from the surface all the way up to 14,500, military operation areas, and the like, but those are outside the scope of this airspace primer and they can best be found by spending a little time with a sectional chart and its legend. Apps like Foreflight for airplane pilots and Kitty Hawk for drone pilots can help to stay in the airspace you want – or more importantly out of the airspace you don’t want to be in. You can have a look at a sectional chart here and begin looking for areas of airspace. Remember, before you get into the nuances, exceptions and random unusual areas of airspace, you must start by having a good working visualization of how the basic airspace works. Then, if you can figure out how to mark the sky with the various airspace boundaries, we could make a comfortable living pitching it to the FAA.

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1 Comment

  1. confortsfromhome.com

    Did you know that to date the FAA has only approved 81 airspace authorizations.

    Reply

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