Control tower

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The control tower at Amsterdam Schiphol Airport.

Inside the control tower at Misawa Air Base, Japan.

A Surface Movement Radar at Schiphol airport, used to assist tower controllers at night or in poor visibility

A control tower (ATCT) is the name of the air traffic control unit responsible for movements around an airport, and is also the name of the building from which the unit operates. Most of the world's airports are non-towered or mandatory frequency — only a small minority of the busiest airports have enough traffic to justify a control tower, though some airports may open temporary tower units during special events like the Oshkosh Airshow.

The worlds highest control tower off the ground is Vancouver Harbour Control Tower, situated on top of the 142 meter skyscraper 200 Granville square, in Downtown Vancouver, Canada

Permanent control tower structures generally rise high above other buildings at an airport to give air traffic controllers a view of aircraft moving on the ground and in the air around the airport, though temporary tower units may operate from trailers or even portable radios outside. Full control tower structures usually have windows that circle the entire top floor, giving 360 degrees of viewable area. The windows are usually tilted outwards, because otherwise the controllers inside would see the reflection of equipment behind them. The ceiling may also be painted black.^[1]

Medium-traffic airports may have only one controller staffing the control tower, and may not keep the tower open 24 hours per day. Busier airports usually have space for several controllers and other support staff, and operate 24 hours per day, 365 days per year.

Control Towers typically contain the following:

radios for communication with aircraft, linked to controllers' headsets or to microphones and speakers;
a telephone system that connects dedicated voice lines and public telephone lines via quick-dial systems to controllers' headsets, allowing them to talk to other controllers and outside parties;
a strip board allowing Flight Progress Strips to be used (however in some towers these have been replaced by a computerised system);
a light gun for communication with aircraft via aviation light signals in the event of a radio failure;
wind and pressure gauges.

Other, optional equipment includes the following:

an Aerodrome Traffic Monitor, which is a small radar display that is not used for separation purposes but allows controllers to see the aircraft flying in the vicinity of the airport;
a Surface Movement Radar displaying aircraft and vehicles on the airport to assist controllers at night and in poor visibility.