Introduction
The National Airspace System (NAS) is the network of
all components regarding airspace in the United States.
This comprehensive label includes air navigation facilities,
equipment, services, airports or landing areas, sectional charts,
information/services, rules, regulations, procedures, technical
information, manpower, and material. Many of these system
components are shared jointly with the military. To conform
to international aviation standards, the United States adopted
the primary elements of the classifi cation system developed
by the International Civil Aviation Organization (ICAO).
This chapter provides a general discussion of airspace
classifi cation. Detailed information on the classifi cation of
airspace, operating procedures, and restrictions is found in
the Aeronautical Information Manual (AIM).
The National
Airspace System
Chapter 8
Figure 8-1. Each student, pilot, and instructor should have a current sectional chart
for the flight area.
This handbook departs from the conventional
norm, in that the airspace discussions are
presented in reverse order, in the belief that it
is much easier to learn the airspace from least
complicated to most complicated; also, the
information presented for basic visual fl ight
rules (VFR) weather minimums is only that
necessary for weight-shift control (WSC)
aircraft operations.
The two categories of airspace are regulatory
and nonregulatory. Within these two
categories, there are four types: uncontrolled,
controlled, special use, and other airspace.
Airspace is charted on sectional charts as
shown in the some examples for the specifi c
airspaces on the chapter. The specific
airspace symbols are shown on the legend
for each sectional chart. [Figure 8-1] The
WSC aircraft pilot should study and refer
to the specifi cs of the AIM; FAA-H-8083-
25, Pilot’s Handbook of Aeronautical
Knowledge; and Title 14 of the Code of
Federal Regulations (14 CFR) part 91 for
additional information regarding airspace
and operations within that airspace.
Uncontrolled 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.
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 fl ight
in an unfamiliar area. [Figure 8-4]
There are no communications, entry,
equipment, or minimum pilot certifi cate
18,000 MSL (FL 180)
10,000 MSL sport pilot limit
Class E controlled airspace
Class E controlled airspace
Class A
Class E
drops to ground
around some
airports
Class E
drops to 700 feet
AGL over many airports
Class G
above
1,200 feet
AGL in
some
areas
Class G uncontrolled airspace
AGL—above ground level FL—flight level MSL—mean sea level
1,200’
AGL
everywhere
not marked on sectional
Figure 8-2. Class G uncontrolled airspace and Class E controlled airspace.
60,000 MSL (FL 600)
18,000 MSL (FL 180)
10,000 MSL Sport Pilot Limit
Class A
Class E
Class B
Class C
4,000’ AGL
Class D
2,500’ AGL
Class GClass GClass GClass G
700’ AGL
1,200’
AGL
Class E
AGL—above ground level FL—flight level MSL—mean sea level
700’
AGL
1,200’ AGL1,200’ AGL
Figure 8-3. Class G airspace extends from the surface to the base of controlled airspace (Class B, C, D, and E).
Figure 8-5. Requirements for airspace operation.
CLASS G from surface to 700 feet AGL.
CLASS G from surface to 700 feet AGL.
CLASS G from surface to 700 feet AGL.CLASS G from surface to 700 feet AGL.
CLASS G from surface
to 700 feet AGL.
CLASS G from surface
to 700 feet AGL.
CLASS G from surface
to 12,000 feet AGL.
CLASS G from surface
to 12,000 feet AGL.
CLASS G from surface
to 1,200 feet AGL.
CLASS G from surface
to 1,200 feet AGL.
CLASS G from surface
to 12,300 MSL.
CLASS G from surface
to 12,300 MSL.
Figure 8-4. Class G airspace as shown on a sectional chart.
requirements to fl y in uncontrolled Class G airspace unless
there is a control tower. [Figure 8-5]
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 fi xed-wing training
aircraft. In this case, the mnemonic recalls, “Clouds 1,000,
500, and 2,000.”
Visibility in Class G airspace below 10,000 MSL day fl ight
is one statute mile (SM) for private pilots and three SM for
sport pilots. See Figure 8-6 for specifi c Class G weather
minimums for WSC pilots.
Controlled Airspace
Controlled airspace is a generic term that covers the different
classifi cations of airspace and defi ned dimensions within
which ATC service is provided in accordance with the
airspace classifi cation. 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* Flight visibility† Distance from clouds
Class A Not applicable Not applicable
Class B 3 statute miles Clear of clouds
Class C 3 statute miles 500 feet below
1,000 feet above
2,000 feet horizontal
Class D 3 statute miles 500 feet below
1,000 feet above
2,000 feet horizontal
Class E Less than 10,000 feet MSL . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 statute miles 500 feet below
1,000 feet above
2,000 feet horizontal
At or above 10,000 feet MSL* . . . . . . . . . . . . . . . . . . . . . . . . . . 5 statute miles 1,000 feet below
1,000 feet above
1 statute mile horizontal
Class G 1,200 feet or less above the surface (regardless of MSL altitude)
Day, except as provided in 14 CFR section 91.155(b). . . . . . . . 1 statute mile † clear of clouds
Night, except as provided in 14 CFR section 91.155(b). . . . . . . 3 statute miles 500 feet below
1,000 feet above
2,000 feet horizontal
More than 1,200 feet above the surface but less than 10,000 feet MSL
Day. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 statute mile † 500 feet below
1,000 feet above
2,000 feet horizontal
Night ‡ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 statute miles 500 feet below
1,000 feet above
2,000 feet horizontal
More than 1,200 feet above the surface and at or above 10,000 feet MSL*
5 statute miles 1,000 feet below
1,000 feet above
1 statute mile horizontal
† Sport pilots must maintain 3 SM or better visibility in all airspace.
‡ Sport pilots are not authorized to fly at night.
* Sport pilots are not authorized to fly above 10,000 feet MSL.
Basic VFR Weather Minimums
Figure 8-6. Basic weather minimums for WSC operations in the different classes of airspace.
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.
RestrictedRestricted
RestrictedRestricted
Military
Operations
Area
Military
Operations
Area
CLASS D
Airspace
CLASS D
Airspace
Surface to
6,400 MSL
Surface to
6,400 MSL
Class E
to surface
Class E
to surfaceCLASS G surface to 700 AGL. CLASS E above 700 AGL
CLASS G surface to 700 AGL. CLASS E above 700 AGL
CLASS G surface
to 1,200 AGL.
CLASS E above
CLASS G surface
to 1,200 AGL.
CLASS E above
Figure 8-8. Class D airspace shown on a sectional chart.
CLASS E above 700 AGL
CLASS E above 700 AGL
CLASS E above 700 AGLCLASS E above 700 AGL
CLASS E above 700 AGLCLASS E above 700 AGL
CLASS E above 1,200 AGLCLASS E above 1,200 AGL
CLASS E to surfaceCLASS E to surface
CLASS E to surface
CLASS E above 12,300 MSLCLASS E above 12,300 MSL
FEDERAL AIR WAYFEDERAL AIR W
AY
FEDERAL AIR WAYFEDERAL AIR W
AY
FEDERAL AIR WAY
FEDERAL AIR WAY
CLASS E above 1,200 AGLCLASS E above 1,200 AGL
Figure 8-7. Class E airspace as shown on a sectional chart.
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 fi ve 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 specifi c 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 specifi c 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
confi guration 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 traffi c 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 specifi c 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
Figure 8-9. Class C airspace as shown on a sectional chart.
Figure 8-10. Class B airspace as shown on a sectional chart.
and passenger enplanements (larger airline operations).
[Figures 8-3 and 8-9] This airspace is charted in feet MSL,
and is generally of a fi ve 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 fl y into Class C airspace by contacting
the control tower fi rst, 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 fl y 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 signifi cant air traffi c, 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 traffi c.
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 confi guration 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 traffi c 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]