Area control service

The function of 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, area control can be provided without radar). Some centers have computers (1) which automate many of the routine functions (2, 3) of the controller.

In order to maintain a controller's workload (4) at a level within his capability, the centre's airspace is divided into sectors. (5)

It is essential that the controller know the position and future plan of every aircraft within his sector. To accomplish this, flight progress boards (6) are used on which are placed flight progress strips (7) which contain all the pertinent current flight data (8) such as the following:

Aircraft identification (9)

Type of aircraft

Point of departure

Destination

Flight planned route

Filed true airspeed (10)

The controller's and pilot's estimated time over the current reporting point

Actual time over reporting point or fix

Flight level in hundreds of feet

Clearance information

Where a centre does not have the requisite computer, flight progress strips are manually (11) prepared and handled.

Approach control facilities use radar and flight progress strips in the same manner as area control centres.

A controller has to decide which separation standard he will apply to aircraft in flight. If he applies lateral separation (12) he must maintain aircraft on different routes or in different geographical areas.

In applying longitudinal separation (13) the controller maintains an interval between aircraft. Longitudinal separation is established by requiring aircraft to depart at a specified (14) time; to arrive over a reporting point at a specified time; or to hold over a reporting point until a specified time. A 15-minute, time-spacing interval between two 600 mph jet aircraft means that they are separated longitudinally by 150 miles.

Vertical separation (15) is obtained by assigning different flight levels to aircraft, in other words, they are separated by a specified vertical distance.

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