Air Traffic Management System

AirspaceTRACON (Terminal Radar Approach Control)

TRACONs are facilities containing radar operations from which air traffic controllers direct aircraft  during the departure, descent and approach phases of flight. One TRACON can handle the air traffic for several different airports in its sector. The airspace of a TRACON has various dimensions depending upon its location within the US, and the size and number of airports it serves. Dallas-Fort Worth TRACON, for example, monitors the airspace from 17,000 feet and below, at a radius of approximately 40 miles from the DFW airport.

The TRACON controllers direct aircraft that are transitioning from the en route phase through to the approach phase into a destination airport located within the TRACON’s airspace. There is more than one controller position in the TRACON. These positions are designated as follows:

Typically a series of TRACON controllers direct an aircraft through 2 stages of descent (high altitude to low altitude). The high altitude controller will hand off the aircraft to the low altitude controller who then hands off the aircraft to the approach controller. The approach controller merges the many descending aircraft flying toward the same destination airport into one line of air traffic maintaining safe separation. When the aircraft reach about 50 miles outside the destination airport the approach controller performs an electronic transfer and hands the aircraft off to the Feeder Controller. Once the arriving aircraft are within the airport’s airspace, they are handed off to the Local Controller located in the airport’s control tower. The aircraft are then no longer being monitored by the controller’s in the TRACON.

TRACONs also control an aircraft that is transitioning after takeoff to the departure phase until the flight is handed off to the Air Route Traffic Control Center (ARTCC) for its en route phase. The Departure Controller in the TRACON routes the ascending aircraft immediately upon takeoff via a preferential departure route (PDR) leading away from the departure airport.

There are 185 TRACON facilities in the United States. TRACONs are usually located as separate facilities from airports. There are typically more than 3 TRACONs within a Center’s airspace. In some locations within the US, TRACONs handle traffic for only a single major airport. These TRACONS are then located in the Air Traffic Control Tower of that airport. TRACONs in areas servicing several major airports like the Northern California TRACON and Potomac TRACON in the Washington, DC area are often located off airport grounds. Combining TRACON facilities in many areas should enhance operational efficiency. Multiple-airport TRACONs can cover several hundreds of square miles. A large TRACON facility could have 40 or more controllers working multiple sectors around several airports.

Currently, the Baltimore-Washington region is served by four major airports:

These are all located within a geographic area typically served by only one airport. Because of the high density population and the high density air traffic, each of these four airports has its own air traffic control tower as well as its own TRACON.

Each TRACON has responsibility for controlling specifically defined and limited sections of "airspace." That responsibility involves ensuring that all aircraft entering or departing the airspace are kept separated at safe distances. When necessary TRACONs reroute aircraft to avoid dangerous weather patterns. A TRACON’s total airspace is subdivided into small sections called “sectors.” Each sector is assigned to an individual air traffic controller who works in the TRACON facility.

 

Denver's VFR traffic

Display of Denver Center's VFR traffic.

The TRACON controller directs the movement of aircraft in and out of that airspace by monitoring a radar screen and maintaining voice contact with pilots.

Although the controller's individual responsibility is only for his or her own sector, all controllers within a TRACON have full radar information on all the aircraft that are under control of the entire TRACON facility. In addition, these controllers are able to communicate with one another instantly- something that contributes significantly to assuring the safety of aircraft passengers.

By contrast, in a control environment such as that which exists within this region today, controllers in one TRACON have limited ability to communicate with controllers in adjacent TRACONs. This is true even though aircraft will pass from the airspace controlled by one TRACON into that of another. "Hand-offs" (the electronic transfer of control and separation responsibility between TRACONs) are routine within the Washington/Baltimore area. To assure the safety of such hand-offs today aircraft in this region often must use longer routes than would be necessary in a single TRACON. In other words, some efficiency is sacrificed to safety concerns, as it should be in a system that puts safety first.

SFO Class Airspace Image

San Francisco Class Airspace image

 

TRACON jurisdictions are not the same as Class "B" or Class "C" airspace. For example, compare the Bay Area Class "B" airspace and the Bay TRACON airspace shown Below.

Bay Tracon Image

Bay TRACON image

TRACONs control air traffic landing at, departing from, and over-flying airports.

The following graphic depicts the air traffic flow at the Orlando, FL MCO TRACON when landing to the north. (The MCO identifier is derived from the fact Orlando International Airport was formerly McCoy AFB.)

MCO South Operations Image

MCO South Operations image

Green arrows depict arriving aircraft

Yellow arrows depict departing aircraft

Blue arrows depict aircraft over-flying the MCO TRACON