A control zone (CTR) in
aviation
Aviation includes the activities surrounding mechanical flight and the aircraft industry. ''Aircraft'' includes fixed-wing and rotary-wing types, morphable wings, wing-less lifting bodies, as well as lighter-than-air craft such as hot a ...
is a volume of
controlled airspace, usually situated below a
control area, normally around an airport, which extends from the ''surface'' to a ''specified upper limit'', established to protect air traffic operating to and from that airport. Because CTRs are, by definition, controlled airspace, aircraft can only fly in it after receiving a specific clearance from air traffic control. This means that
air traffic control
Air traffic control (ATC) is a service provided by ground-based air traffic controllers who direct aircraft on the ground and through a given section of controlled airspace, and can provide advisory services to aircraft in non-controlled airs ...
at the airport know exactly which aircraft are in that airspace, and can take steps to ensure aircraft are aware of each other, either using separation or by passing traffic information.
In the USA the term control zone is no longer used and has been replaced by airspace class D. Typically it extends 5 miles in diameter with a height of 2500 ft AGL (above ground level) around small commercial airports. Aircraft are required to establish radio contact with the control tower before entering and to maintain in contact while in class D airspace. This implies that an aircraft must be equipped with at least a portable radio to fly in Class D airspace.
In the UK, control zones are normally class D airspace and usually extend from the surface to 2000 ft AGL. They can be observed to be usually rectangular, extending along the axis of the main runway, although irregular shapes may be used where more complex airspace dictates this (see Liverpool and East Midlands). A
control area (CTA) is often placed between a CTR and nearby airways to give uninterrupted controlled airspace to airways arrivals and departures.
In Germany, control zones are a special type of class D airspace, called ''D (CTR)''. The main difference to the regular German class D airspace is, that within a CTR there is a minimum required cloud ceiling of 1500 ft AGL.
Deutsche Flugsicherung
Deutsche Flugsicherung (DFS) is the company in charge of air traffic control for Germany. It is a company organized under private law and 100% owned by the Federal Republic of Germany. Since January 1993, DFS has been controlling air traffic in Ge ...
Airspace Structure/Visual Flight Rules in the Federal Republic of Germany – Example
See also
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Airway (aviation)
In the United States, airways or air routes are defined by the Federal Aviation Administration (FAA) in two ways:
"VOR Federal airways and Low/Medium Frequency (L/MF) (Colored) Federal airways"
These are designated routes which aeroplanes f ...
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Flight information region
In aviation, a flight information region (FIR) is a specified region of airspace in which a flight information service and an alerting service (ALRS) are provided. The International Civil Aviation Organization (ICAO) delegates which country is re ...
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Terminal control area
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Area control center
In air traffic control, an area control center (ACC), also known as a center or en-route center, is a facility responsible for controlling aircraft flying in the airspace of a given flight information region (FIR) at high altitudes between ai ...
(for high-altitude traffic between airports)
References
{{Commercial air travel
Air traffic control