'Airspace' means the portion of the atmosphere controlled by a particular country on top of its territory and
territorial waters or, more generally, any specific three-dimensional portion of the atmosphere.
Airspace is divided into two basic types:
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Controlled airspace exists where it is deemend necessary that
air traffic control has some form of positive executive control over aircraft flying in that airspace.
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Uncontrolled airspace is airspace in which
air traffic control does not exert any executive authority, although it may act in an advisory manner.
Airspace may be further subdivided into a variety of areas and zones, including zones where there are either restrictions on flying activities or complete prohibition of flying activities.
By international law, the notion of a country's sovereign airspace corresponds with the maritime definition of
territorial waters as being 12 miles out from a nation's coastline. Airspace not within any country's territorial limit is considered international, analogous to the "
high seas" in maritime law. However, a country may, by international agreement, assume responsibility for controlling parts of international airspace, such as those over the oceans. For instance, the
United States provides air traffic control services over a large part of the Pacific Ocean, even though the airspace is international.
There is no international agreement on the vertical extent of sovereign airspace (the boundary between
outer space— which is not subject to national jurisdiction— and national airspace), with suggestions ranging from about 30 km (the extent of the highest aircraft and balloons) to about 160 km (the lowest extent of short-term stable orbits). In the United States, anyone who has flown above 50 miles (80 km) is considered an
astronaut, and descending shuttles have flown closer than 80 km over other nations, such as Canada, without requesting permission first.
[1]
References
1. Robert E. White, ''Space Weapons Ban: Thoughts on a New Treaty'' (accessed July 27, 2007)
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US airspace, as described in the Aeronautical Information Manual
See also
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Airspace class