What Are Airspace Classes?

The National Airspace System divides up the classifications of airspace based on:

There are two categories of airspace or airspace areas: regulatory and non-regulatory. Regulatory airspace has a set of specific regulations that govern that area; whereas non-regulatory airspace is just used to advise or warn pilots of the operations that are conducted within the airspace.

Regulatory airspace consists of:

Non-Regulatory airspace consists of:

Within these two categories, there are four types:

Various charts help pilots figure out which airspace they are in. The most common chart is the sectional chart, which is a map for pilots. Sectional charts provide detailed information that includes airspace classes. Each of the different types of airspace has specific requirements that must be met to operate in it.

Class A airspace begins at 18,000 feet above sea level known as mean sea level, or msl, and goes up to 60,000 feet msl. This airspace covers both the 48 contiguous states and Alaska and extends offshore 12 nautical miles. Most of the traffic operating in class A airspace will be commercial airlines or corporate and military jets. Class A airspace is not depicted on the visual flight rules (VFR) charts, because all the aircraft that operate in Class A airspace are required to be operating according to instrument flight rules (IFR).

IFR/VFR: IFR only

Altitude Range: 18,000 feet msl up to and including 60,000

Speed Restrictions: No speed limit except remain slower than the speed of sound

Need ATC Clearance?: Yes

Other Characteristics:

Class B, or Bravo, airspace surrounds the nation’s busiest and largest airports. The main airport that a Class B area has been designated for is considered the primary airport. There can also be other smaller airports within Class B, which are designated as secondary airports. On a VFR sectional chart, look for the solid blue lines to find Class Bravo airspace. The altitudes shown on VFR sectional charts are labeled in msl.

IFR/VFR: Both

The visibility must not be any less than 3 statute miles; the pilot must remain clear of clouds.

Altitude Range: 

Vertically: Located between the surface and 10,000 feet msl, with some exceptions.

Laterally: Distances of the airspace will vary with the local area, with several layers.

A 30-mile ring, known as a Mode-C Veil, surrounds the primary airport of Class B airspace. Class B, because of all the altitude tiers, is sometimes referred to as an upside-down wedding cake.

Speed Restrictions:

There are two speed limitations in Class B airspace:

Need ATC Clearance?: Yes

To operate in Class B airspace:

Other Characteristics: 

Class C, or Charlie, airspace is designated for airports that are not as busy as Class B, but are still busy enough to require radar approach assistance to organize and separate aircraft traveling into and out of the local area. Class C is labeled on a VFR sectional chart using solid magenta lines.

IFR/VFR: Both

To operate VFR inside Class C, visibility must be greater than 3 statute miles and a pilot cannot fly any closer to the clouds than 500 feet below, 1,000 feet above, and 2,000 feet horizontally.

Altitude Range: 

The shape of Class C airspace generally has two cylinders—the inner core, and the outer shelf.

Speed Restrictions:

Need ATC Clearance?: No

Other Characteristics:

Class D, or Delta, airspace is controlled airspace surrounding smaller local airports that are quiet enough not to require any radar separation, but still busy enough to require a control tower. Class D is labeled on a VFR sectional chart using dashed blue lines. The altitudes shown on VFR sectional charts are labeled in msl.

IFR/VFR: Both

To operate VFR inside Class D, visibility must be greater than 3 statute miles, and a pilot cannot fly any closer to the clouds than 500 feet below, 1,000 feet above, and 2,000 feet horizontally.

Altitude Range: 

Speed Restrictions: 

Need ATC Clearance?: No

Other Characteristics: 

Class E, or Echo, airspace is defined as controlled airspace that is not Class A, B, C, or D and is one of the largest parts of the national airspace system. There are seven unique types or locations of Class E airspace. These various types of Class Echo airspace can be found on sectional and other low-altitude charts as long as that airspace begins below 14,500 feet msl.

IFR/VFR: Both

Altitude Range: 

No defined vertical limits to Class Echo. Class E either starts at the surface or a defined altitude, and continues upward until coming in contact with a different class of controlled airspace. The seven types of Class Echo airspace:

Speed Restrictions: 

Need ATC Clearance?: No

Other Characteristics: 

Class G, or Golf, airspace is considered uncontrolled, and makes up the rest of the area that isn’t already Class A, B, C, D, or E. Class G will start at the surface and continue upward until reaching 1,200 feet agl, which is where Class Echo’s en-route domestic areas typically start.

IFR/VFR: VFR

Flying below 1,200 feet agl

Flying above 1,200 feet agl, but less than 10,000 feet msl

Flying both above 1,200 feet agl and 10,000 feet msl

Altitude Range: Anything below Class Echo

Speed Restrictions: 

Need ATC Clearance?: No

Other Characteristics: 

In addition to the six classes of airspace mentioned above, there are other types of airspace. They fall into a category called special use airspace. Special use airspace consists of areas wherein certain activities are being conducted that must be confined to that area, or wherein limitations are imposed upon other aircraft that are not a part of those activities, or both. Special use airspace areas are depicted on aeronautical charts, except for controlled firing areas. 

For regulatory special use airspace, there are prohibited areas and restricted areas. Non-regulatory special use airspace consists of warning areas, military operating areas, alert areas, and controlled firing areas.

Prohibited areas exist where aircraft are not permitted to fly for either security reasons or to protect national welfare. It begins at the surface and extends up to a specified altitude, and is depicted on sectional charts with a blue hashed shape with the letter “P” and a series of numbers, to serve as the identifier of that area.

Restricted areas contain hazardous activities to non-participating aircraft, such as artillery firing, aerial gunnery, or guided missiles. Aircraft are not allowed to fly within the area when it is active unless they have permission. It begins at the surface and extends up to a specified altitude, and is depicted on sectional charts with a blue hashed shape with the letter “R” and a series of numbers, to serve as the identifier of that area.

Warning areas also contain hazardous activities to non-participating aircraft, and warn nonparticipating pilots of potential danger, without preventing them from operating within that area. There are over domestic and international waters, three nautical miles from the coast. It begins at the surface and extends up to a specified altitude, and is depicted on sectional charts with a blue hashed shape with the letter “W” and a series of numbers, to serve as the identifier of that area.

Military operating areas, or MOAs, contain military activities and serve to separate certain military training from IFR traffic. VFR traffic may still fly through the area whether it is in use or not but should exercise caution. MOAs start at a designated altitude and extend up to, but not including FL180 and are depicted on sectional charts using magenta hashed lines and are given names such as “Rainier MOA”, “Chinook MOA”.

Alert areas inform pilots of areas that have high volume traffic usually due to pilot training, or an unusual type of aerial activity. Transitory aircraft should use extra caution in these areas. Alert areas on a sectional chart are depicted with magenta hashed lines, with the letter “A,” and a series of numbers that serve as the identifier. 

Controlled firing areas, or CFAs, allow such activity to take place in a confined area to not create a hazard to aircraft. Unlike other hazardous activities that cordone off specified airspaces, activities are immediately suspended when a nonparticipating aircraft appears to be approaching the area. CFAs aren’t charted since they do not require pilots to alter their course.

Temporary flight restrictions are short-term blocks of airspace used to temporarily prevent or limit nonparticipating aircraft from entering that area. They are usually used for spacecraft launches, natural disaster relief, forest fires, sporting events, or to protect prominent public figures. 

Other auxiliary airspaces include airport advisory areas, air defense identification zones, military training routes, VFR flyways, VFR corridors, VFR transition routes, terminal radar service areas, national security areas, and finally, U.S. Wildlife refuges, parks, and forest service areas.

Every time you get into an aircraft, you are surrounded by airspace. It is important to understand the rules and requirements so that you can safely and legally. Subscribe to FLYING Magazine to learn more.