The function of the area control is to provide Air Traffic Control service for controlled flights except for those parts of flight where the ATC service is provided by approach control or by aerodrome control. Its area of control usually includes many thousands of square miles of airspace. With radar, controllers can position aircraft and achieve the desired safe and expeditious flow of traffic. (However, the control can be provided without radar). Some centres have computers which automate many of the routine functions of the controller.
The centres’ airspace is divided into sectors. It is essential that the controller know the position and future plan of every aircraft within his sector. To accomplish this, flight progress boards are used on which are placed flight progress strips which contain all the current flight data such as the following:
Aircraft identification
Type of aircraft
Point of departure
Destination
Flight Planned Route
Filed true airspeed
The controller's and pilot’s estimates
Time over the current reporting point
Actual time over reporting point
Flight level
Clearance information
A controller has to decide which separation standard he will apply to aircraft in flight. If he applies lateral separation he must maintain aircraft on different routes or in different geographical areas.
A 15-minute time-spacing interval between two 600 mph jåt aircraft means that they are separated longitudinally by 150 miles.
Vertical separation is obtained by assigning different levels to aircraft, in other words, they are separated by a specified vertical distance.