Uncontrolled and Controlled Airspace

Class G Airspace

Class G or uncontrolled airspace is the portion of the airspace that has not been designated as Class A, B, C, D, or E. Class G airspace extends from the surface to the base of controlled airspace (Class B, C, D, and E) above it as shown in Figures 8-2 and 8-3.

Figure 8-2. Class G uncontrolled airspace and Class E controlled airspace.

Figure 8-3. Class G airspace extends from the surface to the base of controlled airspace (Class B, C, D, and E).

Most Class G airspace is overlaid with Class E airspace, beginning at either 700 or 1,200 feet above ground level (AGL). In remote areas of the United States, Class G airspace extends above 700 and 1,200 AGL to as high as 14,500 feet before the Class E airspace begins. [Figure 8-2] The pilot is advised to consult the appropriate sectional chart to ensure that he or she is aware of the airspace limits prior to flight in an unfamiliar area. [Figure 8-4]

Figure 8-4. Class G airspace as shown on a sectional chart.

There are no communications, entry, equipment, or minimum pilot certificate requirements to fly in uncontrolled Class G airspace unless there is a control tower. [Figure 8-5]

Figure 8-5. Requirements for airspace operation.

If operations are conducted at an altitude of < 1,200 feet AGL, the pilot must remain clear of clouds. If the operations are conducted more than 1,200 feet AGL but less than 10,000 feet mean sea level (MSL), cloud clearances are 1,000 feet above, 500 feet below, and 2,000 feet horizontally from any cloud(s). A popular mnemonic tool used to remember basic cloud clearances is “C152,” a popular fixed-wing training aircraft. In this case, the mnemonic recalls, “Clouds 1,000, 500, and 2,000.”

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Visibility in Class G airspace below 10,000 MSL day flight is one statute mile (SM) for private pilots and three SM for sport pilots. See Figure 8-6 for specific Class G weather minimums for WSC pilots.

Figure 8-6. Basic weather minimums for WSC operations in the different classes of airspace.

Controlled Airspace

Controlled airspace is a generic term that covers the different classifications of airspace and defined dimensions within which ATC service is provided in accordance with the airspace classification. Controlled airspace consists of:

Class E
Class D
Class C
Class B
Class A

Class E Airspace

Generally, if the airspace is not Class A, B, C, or D, and is controlled airspace, then it is Class E airspace. Class E airspace extends upward from either the surface or a designated altitude to the overlying or adjacent controlled airspace. [Figures 8-3 and 8-7] Also Class E is federal airways beginning at 1,200 feet AGL extending 4 nautical miles (NM) on each side, extending up to 18,000 feet.

Unless designated at a lower altitude, Class E airspace begins at 1,200 AGL over the United States, including that airspace overlying the waters within 12 NM of the coast of the 48 contiguous states and Alaska, and extends up to but not including 18,000 feet.

There are no specific communications requirements associated with Class E airspace [Figure 8-5]; however, some Class E airspace locations are designed to provide approaches for instrument approaches, and a pilot would be prudent to ensure that appropriate communications are established when operating near those areas.

If WSC aircraft operations are being conducted below 10,000 feet MSL, minimum visibility requirements are three statute miles and basic VFR cloud clearance requirements are 1,000 feet above, 500 feet below, and 2,000 feet horizontal (remember the C152 mnemonic). Operations above 10,000 feet MSL for private pilots of WSC aircraft require minimum visibility of five statute miles and cloud clearances of at least 1,000 feet above, 1,000 feet below, and one statute mile horizontally. [Figure 8-5] See Figure 8-6 for specific VFR visibility requirements.

Towered Airport Operations

All student pilots must have an endorsement to operate within Class B, C, and D airspace and within airspace for airports that have a control tower, per 14 CFR section 61.94 or 14 CFR section 61.95. Only private pilot students can operate within Class B airspace with the proper endorsements per 14 CFR section 61.95. Sport pilots must also have an endorsement per 14 CFR section 61.325 to operate within Class B, C, and D airspace and within airspace for airports with a control tower. [Figure 8-5] All students and Sport pilots have further restrictions regarding the specific Class B airports out of which they may operate, per 14 CFR section 91.131.

Class D Airspace

Class D is that airspace from the surface to 2,500 feet AGL (but charted in MSL) surrounding smaller airports with an operational control tower. [Figures 8-3 and 8-8] The configuration of each Class D airspace area is individually tailored. When instrument procedures are published, the airspace is normally designed to contain the procedures.

Unless otherwise authorized, each aircraft must establish two-way radio communications with the ATC facility providing air traffic services prior to entering the airspace and thereafter maintain those communications while in the airspace. Radio contact should be initiated far enough from the Class D airspace boundary to preclude entering the Class D airspace before two-way radio communications are established. It is important to understand that if the controller responds to the initial radio call without using the WSC aircraft’s call sign, radio communications have not been established, and the WSC aircraft may not enter the Class D airspace.

Many airports associated with Class D airspace do not operate a control tower on a 24-hour-a-day basis. When not in operation, the airspace will normally revert to Class E or G airspace, with no communications requirements. Refer to the AF/D for specific hours of operation airports.

The minimum visibility requirements for Class D airspace are three statute miles; cloud clearances are the 1,000 above, 500 below and 2,000 vertical. [Figure 8-6]

Class C Airspace

Class C airspace normally extends from the surface to 4,000 feet above the airport elevation surrounding those airports having an operational control tower, that are serviced by a radar approach control, and with a certain number of IFR and passenger enplanements (larger airline operations). [Figures 8-3 and 8-9] This airspace is charted in feet MSL, and is generally of a five NM radius surface area that extends from the surface to 4,000 feet above the airport elevation, and a 10 NM radius area that extends from 1,200 feet to 4,000 feet above the airport elevation. There is also a noncharted outer area with a 20 NM radius, which extends from the surface to 4,000 feet above the primary airport, and this area may include one or more satellite airports. [Figure 8-9]

WSC aircraft can fly into Class C airspace by contacting the control tower first, establishing communications (same as Class D), and having an altitude encoding transponder. Aircraft can enter Class C airspace without a transponder if prior permission from ATC is received 1 hour before entry, per 14 CFR section 91.215(d)(3). Aircraft may fly under the Class C upper tier of airspace without a transponder but not over the top of Class C airspace lateral boundaries.

Cloud clearances in Class C airspace are the same as Class D airspace: minimum visibility of three statute miles, and a minimum distance from clouds of 1,000 feet above, 500 feet below, and 2,000 feet horizontal.

Since Class C has significant air traffic, many with larger airplanes creating stronger vortices, the pilot must be aware that the chance of encountering catastrophic wingtip vortices is greater at airports with larger air traffic.

Class B Airspace

Class B airspace is generally airspace from the surface to 10,000 feet MSL surrounding the nation’s busiest airports in terms of IFR operations or passenger enplanements. [Figures 8-3 and 8-10] The configuration of each Class B airspace area is individually tailored and consists of a surface area and two or more additional layers (some Class B airspace areas resemble upside-down wedding cakes), and is designed to contain all published instrument procedures once an aircraft enters the airspace.

Equipment requirements are the same as for Class C airspace; however, due to air traffic congestion, the WSC aircraft pilot requesting entry to Class B airspace may be denied entry. Since aircraft operating in Class B airspace have a radar signature and ATC provides aircraft separation, there is a difference in the cloud clearance requirements. Visibility remains three statute miles, but minimum cloud clearance requirement is to remain clear of clouds. [Figure 8-6]

Airspace Above 10,000′ MSL and Below 18,000′

For WSC aircraft flying above 10,000 feet MSL, the visibility must be greater than 5 SM and cloud clearances increase to 1,000 feet below, 1,000 feet above, and 1 SM horizontal. If the WSC aircraft was not certificated with an electrical system, an altitude encoding transponder is required per 14 CFR section 91.215.

Oxygen is required for the pilot above 12,500 MSL up to and including 14,000 feet MSL if the flight at those levels is more than 30 minutes duration. At altitudes above 14,000 feet MSL, oxygen is required for the pilot during the entire flight time at those altitudes. At altitudes above 15,000 feet MSL, each occupant of the aircraft must be provided with supplemental oxygen.

Class A Airspace

Class A airspace is generally the airspace from 18,000 feet MSL up to and including FL 600, including the airspace overlying the waters within 12 NM of the coast of the 48 contiguous states and Alaska. Unless otherwise authorized, all operations in Class A airspace are conducted under IFR. Class A airspace is not applicable to WSC pilots.