Tower, Approach and Area Control
Civil air traffic control is split into three services. Aerodrome control is the runway, the taxiways, and the circuit. Approach control is the airspace around one or more airports. Area control is the en-route sectors between those terminal areas. A rating for one does not cover the others.
· by Michal Zembol
One flight crosses all three
A longer flight is handed from unit to unit. The tower clears the aircraft to taxi and to take off. Approach climbs it out and transfers it to area control. Area keeps it separated until the descent, then delivers it to the approach unit for the destination. Approach builds the arrival sequence and transfers the aircraft to the tower for the landing.
Each transfer is a change of responsibility. The next unit has the flight only once it has accepted it. A circuit flight can stay with the tower for the whole detail. An overflight can cross area sectors and never speak to a tower.
Aerodrome control
Aerodrome control is responsible for aircraft and vehicles on the manoeuvring area, and for aircraft flying in the vicinity of the aerodrome. The manoeuvring area is the runways and the taxiways. It does not include the apron, where aircraft park, unless that airport has given the tower that work.
The job is usually done from a control tower, which is why it is called tower control. A busy tower often splits the runway from the taxiways. A quiet one is often one person. The longer account is aerodrome control.
Approach control
Approach control works the airspace around the airport, above and outside the circuit, and inside the area sectors. One unit can serve several airports. The boundary is the one published for that unit.
The controller orders arrivals so they reach the runway at a rate the tower can land, and climbs departures clear of that sequence. Approach does not issue the landing clearance. The tower does. The longer account is approach control.
Area control
Area control works flights en route, in sectors between the terminal areas. The work is done in an area control centre. A controller is responsible for the sectors they are checked out on, not for the whole centre. When traffic is light, sectors are combined. When it grows, they are split again.
An area controller does not sequence the runway and does not control the taxiways, even when the flight will land within the hour. The longer account is area control.
A rating for one is not the other two
Most people qualify first for one kind of unit. The endorsement is for that unit: one aerodrome, one approach unit, or the sectors at one centre. Another tower is another endorsement. A move from a tower to approach, or from one centre to another, is further training.
Some states also split procedural control from surveillance control, so a rating worked without radar is not the rating worked on a surveillance display. The names are the state's. How a licence, a rating, and a unit endorsement fit together is Licence, Rating and Unit Endorsement.