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U.S.: Understanding Class B Airspace for Hobbyist Model UAS Pilots
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Mark The Droner
Flight distance : 2917 ft
United States

I've never seen an adequate explanation for this topic on any forum.  This morning I think I've finally figured it out and I thought I'd share.  This thread has to do with Part 101 / Sec 336 / model / hobbyist / recreational drone pilots flying in the USA.  

First, as a hobbyist, you may already know, and if not, you should know that flying in Class B airspace requires "clearance" with ATC, meaning you must at least have had a short two-way conversation with the airport / tower - and your drone flight must be approved for flying in Class B by the tower.  The idea of "notifying" the tower or airport is not good enough in Class B regardless of what Sec 336 states regarding notifying airports.  That's because it can be argued that flying a sUAS (model aircraft) in Class B airspace without notification or clearance or a transponder endangers "the safety of the national airspace system," which is specifically and expressly forbidden as written in Section 336 (b) and also FAR Part 101.43.

This rule as it applies to hobbyists is also specifically outlined on the FAA site - see the last sentence on this page:

So what is Class B Airspace?

Class B airspace is the airspace around a large airport that has been designated as Class B by FAA.  It is unique airspace because it is so very, very busy.  In fact, it's so busy that all manned aircraft are required by law to have a transponder on their aircraft so that ATC can instanly identify the aircraft's altitude if they're within 30 nautical miles of the airport (google Mode C Veil for more info).  There are currently 37 airports which are designated Class B.  When you think of Class B, it would be helpful to think BUSY, and also think BLUE - because the Sectional Charts, when referring to Class B airspace, are always written in blue print, and the areas are designated with solid (not dashed or hashed) blue lines.  

Here is a list of the 37 Class B airports: ... n_the_United_States

Class B airspace (and Class C) looks like an upside down wedding cake, but we're only concerned with the layer closest to the surface which is to say, we're only concerned about the lowest tier.  The other layers are too high and we won't be flying in that airspace anyway, so there's no need to worry about those upper tiers.  

If you plan to fly your UAS near one of these airports, you would be wise to figure out where, like exactly, the line is located that begins that lower tier of class B airspace relative to your flight.  So you may want to look at a sectional chart.  

Here is a list of Class B airports with links to sectional charts (click on the PDF). ... gital_products/vfr/

Let's look at a relatively simple one - here's the one for St. Louis: ... s/St_Louis_97_P.pdf

You want to look for the wide blue cocentric solid line (not dashed or hashed) circles surrounding the airport.  As a model pilot, the smallest blue circle is the one you are concerned with.  Within that smaller circle, you can see "80" with a line under it, and then "SFC" under that line.  This tells you that the first tier of Class B is within that circle and extends from the ground up to 8,000 feet.  This is all Class B.  So you don't want to fly within that smallest circle without ATC clearance.  But how wide is that circle?  What is the distance from the airport to the edge of that circle?  Most of the time, the line circle is 14 statute miles in diameter, or put another way, the line extends about 7 statute miles from the center of the airport, but it varies depending on the airport and you will usually have to measure it or otherwise figure it out for yourself to know for sure.  On this chart, there is a measuring tool at the bottom of the map.  If you measure with that, you'll see the circle is about 14 statute miles in diameter which means the circle's edge is 7 miles from the center of the airport.  So for example, if you are six miles from the airport, although you are relieved from "notifying" the airport/tower, you are still required to get clearance from the airport's ATC because it's Class B airspace.  

Now let's look at a more complicated chart - Atlanta: ... s/Atlanta_100_P.pdf

This time, the circle isn't a perfect circle, it's narrower north and south, and wider east and west of the airport.  If you measure using the measuring tool on top, you can see those wide areas are about 16 statute miles apart which makes the Class B airspace a distance of 8 miles from the middle of the airport extending east and west.  But the area of Class B to the north and south of the airport is only about 5.5 miles from the airport.

Las Vegas is another oddly-shaped one.  Besides the main area near the airport, it has an arm that extends a whopping 28 statute miles to the NE of the airport, all of which is Class B airspace from an inch off the ground to 10,000 ft. ... /Las_Vegas_99_P.pdf

To quickly and easily see a sectional chart for your specific area, one way is to go to, enter an address, click on the map link, and then click on Airspace Sectionals.

Another method to see the Class B boundaries relative to your location is to use the Airmap app as if you were flying Part 107.  You can toggle back and forth between Sec 336 and Part 107 to see the 5 mile radius relative to the Class B boundaries.  You can see the 5 mile radius is actually inadequate in regards to a Class B airport.

Remember - as a model pilot, you must either get ATC approval when flying in Class B, or fly somewhere else.  

Hope this helps.


Use props
Second Officer
Flight distance : 123763 ft
United States

Very informative for me. Thanks
Use props
Flight distance : 2438094 ft

Very good read!
Use props
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