The control tower

The control of air traffic on, or in the vicinity of an aerodrome, is provided by the control tower. In most cases the tower is located on top of the terminal building and, is restricted (1) to authorized personnel only. The aerodrome controller, who is located in the " tower cab ", (2) provides separation between aircraft arriving and departing, and also controls aircraft and vehicles manoeuvring (3) on the manoeuvring area.

Approaching aircraft, particularly those operating under VFR, generally contact the aerodrome controller while still several miles away. The aerodrome controller informs the pilot of the runway in use, (4) the wind direction and speed, the altimeter setting, as well as information on other traffic in the area.

Approaching the aerodrome, the pilot joins the traffic circuit (5) on the downwind leg. (6) The aerodrome controller then advises the pilot of his landingsequence (7) giving such instructions as, "You are number two to land following the Cessna on final approach", (8) or, "You are number three following the 707 on base leg ". (9)

The tower's "tools" include a number of radio transmitters and receivers used to communicate with pilots, and a signalling lamp (10) to send control signals to any aircraft not radio equipped or with a radio that is not properly working. The tower's radio equipment may be used with microphone (11) and loudspeakers (12) or with a headset. (13) There is a wind speed indicator (14) and a wind direction indicator (15) at each controller console. (16) A further instrument is the altimeter setting indicator. (17) It is from this instrument that the controller advises the pilot of the current altimeter setting which the pilot sets on his aircraft altimeter.

At some busy airports an Automatic Terminal Information Service (ATIS) is available to pilots of departing and arriving aircraft. This service consists of a continuous radio broadcast on a special frequency of recorded and periodically updated no control information. Included is information regarding ceiling, visibility, wind direction and speed, altimeter settings, and runway in use. Where ATIS is not available, the tower provides this information.