Page 137 - Planning and Design of Airports

106 Airp o r t Pl anning

as well as those flying on instrument-based approach and departure
procedures to or from an airport. Specifically, Class E airspace exists in
most parts of the United States, from the surface, 700 ft AGL, or 1200 ft
AGL to 14,500 ft AGL, and 3 nm surrounding the nation’s airways.
Any airspace that does not fall within Class A, B, C, D, or E air-
space is considered Class G, or uncontrolled airspace. This airspace is
found only at very low altitudes (typically less than 700 or 1200 ft
AGL) or in rural areas of low volume air traffic. Within Class G air-
space, aircraft may move freely as long as there is sufficient visibility
(1 mi during day hours, 3 mi during night hours, 5 mi day or night
when above 10,000 ft AMSL) to see and avoid other air traffic.
Within the National Airspace System are a number of special use
airspace classifications. Some of these define permanent location of
special use or restricted activity, others define locations where flight
operations are restricted for security or other reasons.
Prohibited areas are defined within the NAS as areas prohibited
to any civil aviation activity. These areas are typically defined
around highly sensitive locations, such as the White House in
Washington, D.C.
Restricted areas are defined within the NAS as areas where regular,
but not constant, sensitive operations occur, precluding the safe pas-
sage of civil aircraft. These areas, such as around the Kennedy Space
Center on the east coast of Florida, will periodically restrict civilian
access when sensitive activities are occurring.
Military operations areas (MOAs) are defined as areas with peri-
odic military aviation or other activity. These areas may be entered
only by permission from air traffic control, which coordinates with
the military for civilian use.
Temporary flight restrictions (TFRs) are defined as areas that tempo-
rarily restrict or prohibit most civil aviation operations for reasons of
national security. TFRs are implemented with little advance notice for
a variety of reasons, ranging from protecting nuclear power facilities,
to national sporting events, to the travels of the President of the
United States. Oftentimes, the activation of a TFR will have serious
impacts on the accessibility of an airport to the aviation system.
Figure 3-6 provides an illustration of multiple classes of airspace
within the same region, including Class E airspace under Palatka-
Larkin Airport and restricted areas within a military operations area
south of the airport. Restricted use airspace presents challenges to
airport planners seeking maximum efficiency of air traffic to and
from the airfield.

Airways
Aircraft flying from one point to another have traditionally followed
designated routes. In the United States these are referred to as victor
airways and jet routes. These routes have evolved over time as dis-
cussed below.