Terminal Control Center
Encyclopedia
Air traffic control
Air traffic control is a service provided by ground-based controllers who direct aircraft on the ground and in the air. The primary purpose of ATC systems worldwide is to separate aircraft to prevent collisions, to organize and expedite the flow of traffic, and to provide information and other...
facility usually located within the vicinity of a large airport
Airport
An airport is a location where aircraft such as fixed-wing aircraft, helicopters, and blimps take off and land. Aircraft may be stored or maintained at an airport...
. Typically, the TRACON controls aircraft within a 20-50 nautical mile (37 to 93 km) radius of the major airport and a number of "satellite airports" between surface and 1200 feet (365.8 m) up to between 10000 feet (3,048 m) and 23000 feet (7,010.4 m). A TRACON is sometimes called approach control or departure control in radio transmissions. In the US Air Force it is known as RAPCON (Radar Approach Control), and in the US Navy as a "RATCF" (Radar Air Traffic Control Facility) In Canada, Approach Control may be called arrival or terminal. TRACONs operate in US FAA Class A, B, C, and D airspaces. In class A spaces TRACONs perform transitions of aircraft radio contact to and from the en-route center
Area Control Center
In air traffic control, an Area Control Center , also known as a Center, is a facility responsible for controlling instrument flight rules aircraft en route in a particular volume of airspace at high altitudes between airport approaches and departures...
.
TRACON radar facilities
TRACONs normally have their own radar system that allow air traffic controllerAir traffic controller
Air traffic controllers are the people who expedite and maintain a safe and orderly flow of air traffic in the global air traffic control system. The position of the air traffic controller is one that requires highly specialized skills...
s to track aircraft. This is typically based on one or more Airport Surveillance Radar(s) (ASR), sweeping once every 4-5 seconds. The busiest TRACON in the world (Southern California TRACON - SCT, Callsign SoCal Approach) services 62 airports and is located in San Diego, California. This huge facility utilizes 11 radar sites. Most US terminal Radar Approach Control (TRACON) facilities utilize an ASR-9 with a range of 63 7/8 miles (103 km) and a scan rate (rotation) of approximately 4.5 seconds.
These frequent updates help controllers see the result of direction changes quickly. Larger U.S. TRACONs are able to directly incorporate en route long range Air Route Surveillance Radar(s) (ARSR) into their automated tracking systems as a backup. Smaller U.S. TRACONs also have the capability to make use of CENRAP (CENter RAdar Presentation) as a backup if their primary system fails. This makes use of en-route surveillance radar used by Air Route Traffic Control Centers (ARTCCs). Expanded separation minimums (5 nautical miles (9.3 km) versus 3 nautical miles) are required when in this mode.
Equipment
Most of the United States FAA TRACONs are currently using Common ARTSCommon ARTS
Common ARTS is an air traffic control computer system that air traffic controllers use to track aircraft. The computer system is used to automate the air traffic controllers job by correlating the various radar and human inputs in a meaningful way. This system being used in most of the TRACONs...
equipment. Most of ARTS IIIA and some ARTS IIE sites have been updated to Raytheon's Standard Terminal Automation Replacement System
Standard Terminal Automation Replacement System
The Standard Terminal Automation Replacement System is an air traffic control automation system currently being used in many TRACONs around the United States. STARS is intended to replace the Automated Radar Terminal System...
(STARS) equipment. The program to manage the updates is now called Terminal Automation Modernization/Replacement (TAMR). In the Spring of 2011, it was announced by the FAA that all remaining ARTS equipment will be replaced with STARS equipment. The 11 largest TRACONS will be done first as part of TAMR Segment 3 Phase 1. The fate of the remaining ARTS IIE sites has not been announced by the FAA as of Summer 2011. This program, when announced, will be titled as TAMR Segment 3 Phase 2.
TRACON Control positions
TRACON control positions usually include a radar controller and a coordinator who generally stands behind the radar position.Approach/Departure/Arrival/or Sector Radar controller
The radar controller is responsible for ensuring appropriate separation, and issuing traffic and other local aviation information for aircraft under its control. Additionally, the radar controller is responsible for ensuring all required coordination with other controllers in the tower, TRACON, or en-route center is completed, making required computer entries, and updating the flight progress stripFlight progress strip
- General :A flight progress strip is a small strip of paper used to track a flight in air traffic control . While it has been supplemented by more technologically advanced methods of flight tracking since its introduction, it is still used in modern ATC as a quick way to annotate a flight, to...
s.
Coordinator
The coordinator provides coordination support for the radar controller. He/she will provide inter/intra facility coordination when required for the radar controller and make computer entries.Assistant / "D Side" Controller
Some TRACONs have the ability to staff a second position at the radar console, referred to as a "Assistant" or "D Side" (FAA) controller. This position is responsible for providing direct support by coordinating for the radar controller, managing flight progress strips, and making computer entries. When this position is staffed, the coordinator duties are greatly reduced, allowing him/her to provide support for a number of positions. The support controller may make transmissions on the radio along with the main controller: the support controller focuses on the more procedural aspects of controlling (e.g. holding aircraft) while the main controller focuses on accurately radar-vectoring the approach sequence.TRACON traffic responsibilities
TRACONs are responsible for providing all ATC services within their airspace. Generally, there are four types of traffic flows controlled by TRACON controllers. These are departures, arrivals, overflights, and aircraft operating under Visual Flight Rules (VFR).Departure aircraft
Departure aircraft are received from the control tower from which the aircraft departs and are generally 1000 feet (304.8 m) to 2000 feet (609.6 m) high, climbing to a pre-determined altitude. The TRACON controller working this traffic is responsible for clearing all other TRACON traffic and, based on the route of flight, placing the departing aircraft on a track and in a geographical location (sometimes referred to as a "gate" or "exit") that is set through agreements with the en-route centerArea Control Center
In air traffic control, an Area Control Center , also known as a Center, is a facility responsible for controlling instrument flight rules aircraft en route in a particular volume of airspace at high altitudes between airport approaches and departures...
. This positioning is designed to allow the en-route center to integrate the aircraft into its traffic flow easily.
Arrival aircraft
Arrival aircraft other than Visual Flight Rules aircraft entering the area are received from the en-route centerArea Control Center
In air traffic control, an Area Control Center , also known as a Center, is a facility responsible for controlling instrument flight rules aircraft en route in a particular volume of airspace at high altitudes between airport approaches and departures...
in compliance with pre-determined agreements on routing, altitude, speed, spacing, etc. The TRACON controller working this traffic will take control of the aircraft and blend it with other aircraft entering the center airspace from other areas or "gates" into a single, parallel or perpendicular final for a runway at any of the airports with the TRACON space. The spacing is critical to ensure the aircraft can land and clear the runway prior to the next aircraft touching down on the runway. The TRACON controller will do a hand-off to pass the flight communication to the approach airport tower. That tower controller may also request expanded spacing between aircraft to allow aircraft to depart or to cross the runway in use.
Overflight aircraft
Overflight aircraft are aircraft that enter the TRACON airspace at one point and exit the airspace at another without landing at an airport. They must be controlled in a manner that ensures they remain separated from the climbing and descending traffic that is moving in and out of the airport. Their route may be altered to ensure this is possible. When they are returned to the en-route center, they must be on the original routing unless a change has been coordinated.VFR aircraft
If the class of airspace allows flight under VFRVisual flight rules
Visual flight rules are a set of regulations which allow a pilot to operate an aircraft in weather conditions generally clear enough to allow the pilot to see where the aircraft is going. Specifically, the weather must be better than basic VFR weather minimums, as specified in the rules of the...
, such aircraft are handled as traffic permits. Controllers will provide traffic information to ensure safety with other aircraft, and may even positively separate VFR aircraft from other aircraft, depending on the class of airspace. Controllers spend extra time with these flights in order to avoid vectoring VFR aircraft into IMC
Instrument meteorological conditions
Instrument meteorological conditions is an aviation flight category that describes weather conditions that require pilots to fly primarily by reference to instruments, and therefore under Instrument Flight Rules , rather than by outside visual references under Visual Flight Rules . Typically, this...
. Controllers usually provide information for the pilot about traffic in the immediate vicinity and weather information. This ensures that separation from Instrument Flight Plan (IFR) aircraft is maintained within the controller's coverage area.
Most US airports do not have a TRACON available. In this case, the en-route center will coordinate directly with the tower and provide this type of service where radar coverage permits. In these cases, the separation minimums are greatly increased. In many countries, mid-sized airports without a TRACON have a dedicated Approach Radar Controller based upon the airport itself to sequence inbound flights and to provide radar services to aircraft in the vicinity of the airport.