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 National Airspace System Class Bravo Class B Airspace ­ What You Need To Learn Class B airspace covers some of the busiest commercial airports in the world. Most of the traffic in this airspace is on an IFR flight plan ­ but you'll find VFR traffic inside, too. What do you need to know about Class B Airspace?​
This section covers: ● Why Class B exists ● How it's shown on a sectional chart ● VFR weather minimums ● Radio communication requirements ● Speed restrictions ● Required equipment inside and around Class B 1 of 9 1. Intro ­ Class B Airspace Why Class B Exists Class B airspace protects some of the busiest commercial airports in the world. You'll find a constant flow of airliners and regional jets arriving and departing ­ no matter what the weather, Class B airspace is always busy. Add to the mix corporate jets, cargo operations, and personal aircraft on both VFR (Visual Flight Rules) and IFR (Instrument Flight Rules) flight plans, and you've got a busy mess. To accommodate all of these flights, Class B airspace has some of the strictest equipment and communication requirements of any airspace. But, it's got some of the most lax weather minimums! Why? Air Traffic Control. Air Traffic Control makes Class B airspace possible by constantly monitoring and separating each flight in the airspace. Approach and departure control transitions aircraft into and out of the airspace, and tower controllers sequence them in for landing and takeoff. ATC controls everything you do in Class B airspace. As you're learning about the airspace and its requirements, keep in mind that they're in place so that you and ATC remain in constant communication. ATC is always aware of where you're at and what you're doing. Where It's Found Class B airspace surrounds the largest airports in the United States. Denver International (KDEN), Los Angeles International (KLAX), Chicago O'Hare (KORD), and Atlanta Hartsfield (KATL) are all examples of airports in Class B airspace. Why The Funny Shape? Lots of people say Class B airspace looks like an upside­down wedding cake. While it's not always made up of perfect circles, it is typically narrow at the surface and wide at the top. Take the Denver Class B airspace on the screen for example. There are lots of different sections at different altitudes, but for the most part, it's narrow at the bottom and wide at the top. As planes arrive and depart a Class B airport, they need to be kept at a safe distance from other aircraft in the area. Many of those planes are lower, slower, and in different airspace around the Class B. The cake shape allows arriving and departing aircraft to remain in the Class B airspace as they transition to what's called the 'enroute structure', or the big and relatively open airspace at higher altitudes. At the same time, lower and slower airplanes can continue operating safely at smaller airports outside (but near) Class B airspace. 2 of 9 2. Identification and Boundaries How To Identify Class B Airspace Identifying Class B airspace on a VFR sectional map is pretty easy. There are two markings you need to know to identify Class B airspace: ● Horizontal boundary markings ● Vertical boundary markings Horizontal Boundaries The horizontal boundaries of Class B airspace are marked with a thick blue line. Class B airspace typically has lots of different sections, so expect to see lots of thick blue lines that make up the horizontal limits of the airspace. The different sections of Class B airspace often form a perfect circle, but in some cases, the horizontal boundaries of the B can be all kinds of shapes, due to mountainous terrain, neighboring airports, and other airspace. In this example, the west side of Denver's Class B airspace is 'cut­off' because of its close proximity to the Rocky Mountains. Vertical Boundaries Vertical boundaries of Class B airspace are easy to identify as well. There are two sets of bold blue numbers, separated by a blue horizontal line. Top Number The top number represents the ceiling of Class B airspace in ​
hundreds of feet MSL​
. For example, if the top number is "120," it means the ceiling of Class B for that section is 12,000 feet MSL. The altitudes are inclusive, so if 3 of 9 you're flying in that section at 12,000 feet MSL, you're in Class B. Bottom Number The bottom number represents, you guessed it, the floor of Class B airspace in hundreds of feet MSL. For example, if the bottom number is "080," it means the bottom of Class B airspace for that section is 8,000 feet MSL. So, if you're flying at 8,000 MSL in that section, you're in Class B. SFC When a section of Class B airspace extends to the surface, the bottom number is replaced with the letters "SFC", for "surface." How High Does It Go? Class B airspace typically extends up to 10,000 feet MSL, however, it can vary. In this example, Denver's Class B goes up to 12,000 feet MSL because it's a high­altitude airport. Mode­C Veil Air Traffic Control closely monitors everything that happens inside ­ and around ­ Class B airspace. They need to have accurate altitude information on each aircraft in the area to make sure they remain separated from the Class B traffic. Because of that, all aircraft need to use a Mode­C altitude reporting transponder inside and around Class B airspace. Class B airspace is surrounded by what's known as a "Mode­C veil." The Mode­C veil is marked by a thick magenta ring, with the words "30 NM MODE C" next to it. What does it mean?​
The Mode­C veil is NOT part of Class B airspace​
, however, any flight within the veil requires you to use a Mode­C transponder. How High Does It Go? Mode­C veils extend vertically from the surface to 10,000 feet MSL. Why stop at 10,000 MSL? Because ​
any​
flight above that altitude requires a Mode­C transponder. 4 of 9 3. VFR Weather Minimums Class B Weather Minimums Breakdown VFR weather minimums for Class B can be broken down into four minimum distances: ● Visibility ● Height above clouds ● Height below clouds ● Horizontal distance from clouds Visibility You need to maintain at least ​
3SM​
(statute miles) of visibility to operate VFR in Class B airspace, day or night. Height Above Clouds You need to stay ​
clear of clouds​
when operating above them. What does that mean? It means that your airplane can operate up to, but not touch a cloud. That's pretty close. In the real world, it's a good idea to maintain a little more distance between yourself and the clouds, if possible. After all, nobody wants to accidentally fly into one. Height Below Clouds You're required to remain ​
clear of clouds​
when operating below them as well. Just like flying above them, it's always a good idea to give yourself some room between you and cloud, if possible. Horizontal Distance From Clouds You need to stay ​
clear of clouds​
when operating horizontally from them ­ just like when you are above or below them. 1000' AGL And 3SM Rule When you're in Class B airspace that starts at the surface, you cannot fly under the ceiling (a broken or overcast cloud layer) when the ceiling is less than ​
1000' AGL​
or the visibility is less than ​
3SM​
. When weather conditions are worse than 1000' and 3SM, IFR aircraft could be flying instrument approach procedures, and you wouldn't have the ability to see­and­avoid them as they break out to land. 5 of 9 Special VFR Weather Minimums When you're in Class B airspace that starts at the surface, you may request a ​
Special VFR (SVFR) clearance​
when weather conditions are below the standard minimums. However, many Class B areas don't allow SVFR ­ check FAR 91, Appendix D, Section 3 to see if a Class B airport prohibits SVFR. Under Special VFR, you must remain ​
clear of clouds​
and maintain a ​
flight visibility of at least 1SM​
. If you're taking off or landing, the reported ground visibility must be at least 1SM. You also need to hold a private pilot certificate, and you can only operate SVFR between sunrise and sunset. To operate SVFR after sunset, you must be qualified for instrument flight under FAR 61, and your aircraft must be equipped for instrument flight. To request a Special VFR clearance at a Class B airport, contact Approach Control if you're in the air or Clearance Delivery if you're on the ground. If traffic permits, ATC can clear you into the airspace under Special VFR. However, if aircraft are using instrument approach procedures for the airport, you won't be cleared. 6 of 9 4. Requirements and Restrictions Now that you have VFR weather minimums down, let's talk about the requirements and restrictions to fly into Class B airspace. We'll cover: ● Radio communication ● Speed restrictions ● Required equipment Class B Radio Communication To enter Class B airspace, ​
you need to get a clearance from Air Traffic Control​
. Let's talk about what you need to do and say to get yourself into Class B. What You Need To Say (And Hear) To Get Into Class B All VFR aircraft operating in Class B airspace require a clearance from ATC. To receive the clearance, you need to ​
"request clearance into the Class B" ​
from ATC prior to entering the airspace. When you request clearance into the airspace, ATC gives you a unique transponder squawk code so they can track you on radar. Once they've identified you, they'll tell you that you're​
"cleared into the Class B airspace".​
Those are the key words, and ​
you need to hear them ​
before you enter the airspace. If ATC tells you to 'standby', or anything similar, you need to stay out of the airspace until you are cleared into it. Why Radio Communication Is Required In Class B Airspace With airplanes flying in heavily congested airspace, it's important for Air Traffic Control to keep them separated at a safe distance. Unlike other airspace types, Air Traffic Controllers are responsible for maintaining separation of all aircraft, including VFR airplanes like yours. ​
That doesn't eliminate your responsibility to see­and­avoid other traffic.​
It just means another set of eyes are looking out for you. In other types of airspace (C, D, E and G), controllers are only responsible to maintain separation of IFR aircraft. 7 of 9 Speed Restrictions There are a few speed restrictions that you need to be aware of when you're flying in and around Class B airspace. They are: ● Operating below 10,000 feet MSL ● Operating under Class B airspace ● Operating in a VFR corridor in Class B airspace Below 10,000 Feet MSL If you're below 10,000 feet MSL, you can't go faster than 250kts, but ​
it has nothing to do with Class B airspace​
. ​
Any​
flight below 10,000 feet MSL is restricted to 250kts or less. There are certain cases where it's even less than 250kts, but we'll get to that later on this page. There's one exception to the 250 knot rule: if your aircraft's ​
minimum safe speed​
is faster than 250kts, ATC will allow you to go faster. Good examples of this are probably the SR­71 and Space Shuttle, and unfortunately, not your Cessna 172. Flying Under Class B Airspace If you're flying under Class B airspace (the dark blue area), you need to keep your speed throttled back to ​
200 kts or below​
. You don't need to talk to Air Traffic Control to fly here, you just need to keep your speed down. Why do you need to fly slow? Again, it's to make sure ATC can keep traffic at a safe distance from the jets flying into and out of Class B airports. 8 of 9 VFR Corridor in Class B Airspace If you're flying through a VFR corridor in Class B airspace, you need to keep your speed at 200 kts or below. What's a VFR corridor? It's a 'hole' in Class B airspace that VFR airplanes can fly through without talking to ATC. In the example on the screen, if you're in the corridor, you need to keep your speed down to 200 kts or lower. Required Equipment For Class B There are two pieces of equipment that you need to have on board to fly in Class B airspace: ● Two­way radio ● Mode­C transponder The radio lets you talk to ATC, and the transponder let's them track your position and altitude on radar. 9 of 9