- What is a TRACON or Terminal Control?
- When do pilots need to be helped by a TRACON?
- Where is it usually located and what is the difference between TRACON, En Route and Tower?
What is a TRACON (Terminal Radar Approach CONtrol)?
A TRACON is a term used in the US for what is elsewhere known as the Terminal Control (ICAO terminology), the control in charge of operations around one or more large airports. It doesn't manage ATC at airports, which is provided by TOWERs. TRACON is therefore an intermediate step used for:
- Climbing departing flights received from TOWERs and handing them over to ARTCC.
- Descending cruising flights received from ARTCC and handing them over to airfield TOWERs
FAA describes a TRACON like this:
TRACON controllers generally handle within a 30- to 50-mile radius of an airport and up to 10 000 feet, as well as aircraft flying over that airspace. They are responsible for the safe separation of aircraft flying in the busy areas surrounding airports.
When do pilots need to be helped by a TRACON?
Pilots are directed to a TRACON center either by the Tower controller (for departures), or the ARTCC controller (for descents and transits). The services are delivered by radio from radar data. They typically encompass controlling aircraft during standard approach (STAR) and standard departures (SID). TRACON frequencies are mentioned on instrument plates as Approach (APP CON) and Departure (DEP CON), e.g. for Las Vegas (source):
Typical service provided to a descending aircraft (source):
Typically, arrival traffic is handed off from the ARTCC to the TRACON air space at designated points, called feeder gates, about 30n.mi. from the airport and 10,000 to 15,000ft above ground level. Some airports utilize as many as four or five such gates or corner posts which approximately form a rectangle with the airport at the center [...] Both feeder and final controllers attempt to keep aircraft on a fastest or shortest path to the runway. They often utilize speed changes, altitude changes, and path stretching to ensure proper spacing.
Similarly, climbing aircraft are directed via preferential departure routes towards the en-route airway, before being handed to Air Route Traffic Control Center (ARTCC).
Controllers mostly use the Automated Radar Terminal System (ARTS) or the Standard Terminal Automation Replacement System (STARS) systems to track aircraft:
Philadelphia TRACON (source)
As emphasized by @TomMcW in his comment, smaller airfields don't have an associated TRACON, the approaches and departures are in this case directly managed by controllers at the airfield tower.
Where are TRACON usually located?
TRACON premises by themselves can be located anywhere. Controllers work on radar screens, in the half-light, they don't have a view of the outdoor. Basement rooms are usual.
Potomac consolidated TRACON, operation room (source)
Depending on the country they may be located close to major airports, within the area they control, preferably co-located with towers.
TRACON controlled areas are located around major airports.
- In the US: FAA - Terminal Radar Approach Control Facilities
- In Europe (TCC): See Can multiple airfields be in the same airspace?
From FAA (where are TRACONs located?)
Some TRACONs are located on airport property and some are not, but their locations have no effect on TRACON controllers’ ability to control aircraft, or on the capacity or capabilities of any airport. This is because TRACON controllers rely on radar displays and radio to separate aircraft, unlike tower controllers who control landings and takeoffs visually. In fact, TRACONs do not have windows — a darker environment makes it easier for controllers to see the radar screens.
The article mentions cases like N90 TRACON: It controls traffic from/to major airports in NY area (La Guardia, JFK, Newark Liberty), but is located on Long Island, a location remote from these airports.
FAA arguments for tower and TRACON co-location include savings and easier 24/7 uninterrupted operations.
What is the difference between TRACON, En Route and Tower?
Taking the US ATC system only into account for this discussion. The difference should have been clarified above: Towers handle airport operations, ARTCCs/En-route handle cruise phase, and TRACONs handle climbing and descending aircraft, as well as aircraft transiting between ARTCCs in their controlled areas. Here are some details about Towers and ARTCCs.
1/ Airport operations are controlled by controllers in the tower. They need a view on the runways and other location of the airport.
Tower at Nice / Côte d'Azur airport (LFMN)
Radar techniques are used for tracking aircraft on the ground (ASDE-X) and informations from short range radars can feed various displays, of which the D/BRITE (Digital Bright Radar Indicator Tower Equipment), and more modern Barco.
Takeoff and landing clearances are delivered after visual check of the runway status.
From Nasa's page:
Control towers were established to provide for a safe, orderly, and expeditious flow of air traffic at an airport and in its vicinity. There are four major controller classifications at control towers:
- Flight Data Controller
- Clearance Delivery Controller
- Ground Controller
- Local Controller.
Inside an air traffic control tower (source)
2/ Enroute traffic is controlled by Air Route Traffic Control Center (ARTCC)
Typical sector radar team (source)
From Nasa's page:
ARTCCs, usually referred to as "Centers," are established primarily to provide Air Traffic Service to aircraft operating on IFR flight plans within the controlled airspace, and principally during the en route phase of flight.
There are 21 Air Route Traffic Control Centers (ARTCC) in the United States.
US ARTCC boundaries (source)
Any aircraft operating under Instrument Flight Rules (IFR) within the confines of an ARTCC's airspace is controlled by air traffic controllers at the Center. This includes all sorts of different types of aircraft: privately owned single engine aircraft, commuter airlines, military jets and commercial airlines.
ARTCC manages flights between TRACON airspaces, while they are cruising at high altitude.
(You can listen to ARTCC traffic at LiveATC.net)
First off, there needs to be a distinction between the IFR facility and the Tower. Control towers in the US control runways and surface movement areas, they do not "control" airspace. They do sequence aircraft in the local traffic area but that is a topic for another discussion. TRACONS/RAPCONS are IFR facilities and can issue IFR routes/clearances in the air.
TRACONS typically control airspace around busy airports from the ground up to 15,000ft and about 30 miles around including all airports therein. ARTCC's (Centers or Area control Facilities) cover EVERYTHING else. They provide IFR service from the surface up to the top of controlled airspace in the vast majority of the continental US. There are plenty of smallish airports (especially out west) that have towers without an overlying TRACON. In those areas, the ARTCC is the next layer providing arrival/departure separation, sometimes without radar.
I've been a Professional Airway System Specialist for 29 years. Some of the information in the above article is either misleading or downright incorrect.
Air Traffic Control Towers large enough to require a nearby or co-located TRACON include Digital BRITE Radar displays overhead in the towers.
In my day they were fed by Automated Radar IIA and IIIA systems that were in turn fed by short range (60 mile radars).
Today the Standard Terminal Automation Replacement System (STARS) has replaced the ARTS systems but STARS Automated Radar is still either microwaved to the larger towers or sent via advanced telecommunications.
That information IS NOT used for ground separation it is used by tower controllers to control traffic IN THE AIR that they cannot see which is the majority of the traffic that they control.