A control area is an aviation

Aviation

Aviation is the design, development, production, operation, and use of aircraft, especially heavier-than-air aircraft. Aviation is derived from avis, the Latin word for bird.-History:...

 term that describes a volume of controlled airspace

Controlled airspace

Controlled airspace is an aviation term used to describe airspace in which ATChas the authority to control air traffic, the level of which varies with the different classes of airspace. Controlled airspace is established mainly for three different reasons:...

 that exists in the vicinity of an airport. It has a specified lower level and a specified upper level. It usually is situated on top of a control zone

Control zone

A control zone is an aviation term that describes a volume of controlled airspace, 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...

 and provides protection to aircraft climbing out from the airport by joining the low-level control zone to the nearest airways. In the UK they are generally class A, D or E.

Control areas are particularly useful where there are busy airports located close together. In this case a single CTA will sit over all of the individual airports' CTRs. In larger-scale cases, this is known as a terminal manoeuvring area

Terminal Control Area

A terminal control area , also known as a terminal manoeuvring area in Europe, is an aviation term to describe a designated area of controlled airspace surrounding a major airport where there is a high volume of traffic...

(TMA).