This cache is part of the St. Charles Plane Geoart series.
TRACON
Many airports have a radar control facility that is associated with that specific airport. In most countries, this is referred to as terminal control and abbreviated to TMC; in the U.S., it is referred to as a 'terminal radar approach control' or TRACON. While every airport varies, terminal controllers usually handle traffic in a 30-to-50-nautical-mile (56 to 93 km; 35 to 58 mi) radius from the airport. Where there are many busy airports close together, one consolidated terminal control centre may service all the airports. The airspace boundaries and altitudes assigned to a terminal control centre, which vary widely from airport to airport, are based on factors such as traffic flows, neighbouring airports, and terrain. A large and complex example was the London Terminal Control Centre (LTCC), which controlled traffic for five main London airports up to an altitude of 20,000 feet (6,096 metres) and out to a distance of 100 nautical miles (185 kilometres; 115 miles).
Terminal controllers are responsible for providing all ATC services within their airspace. Traffic flow is broadly divided into departures, arrivals, and overflights. As aircraft move in and out of the terminal airspace, they are 'handed off' to the next appropriate control facility (a control tower, an en-route control facility, or a bordering terminal or approach control). Terminal control is responsible for ensuring that aircraft are at an appropriate altitude when they are handed off, and that aircraft arrive at a suitable rate for landing.
Not all airports have a radar approach or terminal control available. In this case, the en-route centre or a neighbouring terminal or approach control may co-ordinate directly with the tower on the airport and vector inbound aircraft to a position from where they can land visually. At some of these airports, the tower may provide a non-radar procedural approach service to arriving aircraft handed over from a radar unit before they are visual to land. Some units also have a dedicated approach unit, which can provide the procedural approach service either all the time, or for any periods of radar outage for any reason.
In the U.S., TRACONs are additionally designated by a three-digit alphanumeric code. For example, the Chicago TRACON is designated C90.
STARS
The Standard Terminal Automation Replacement System (STARS) is an air traffic control automation system manufactured by Raytheon and is currently being used in many TRACONs around the United States by the FAA. STARS replaced the Automated Radar Terminal System (ARTS) at FAA air traffic control facilities across the US, as well as the previous automation systems employed by the DoD.
The STARS system receives and processes target reports, weather, and other non-target messages from both terminal and en route digital sensors. Additionally, it automatically tracks primary and secondary surveillance targets and provides aircraft position information to the enhanced traffic management system (ETMS). Finally, it also detects unsafe proximities between tracked aircraft pairs and provides a warning if tracked aircraft are detected at a dangerously low altitude. Additional features include converging runway display aid (CRDA) which displays "ghost" targets as an aid to controllers attempting to tightly space aircraft to converging/crossing runways in the terminal environment.
ARTCC
En-route air traffic controllers work in facilities called air traffic control centres, each of which is commonly referred to as a 'centre'. The United States uses the equivalent term air route traffic control center. Each centre is responsible for a given flight information region (FIR). Each flight information region typically covers many thousands of square miles of airspace, and the airports within that airspace. Centres control IFR aircraft from the time they depart from an airport or terminal area's airspace, to the time they arrive at another airport or terminal area's airspace. Centres may also 'pick up' VFR aircraft that are already airborne, and integrate them into their system. These aircraft must continue under VFR flight rules until the centre provides a clearance.
Centre controllers are responsible for issuing instructions to pilots to climb their aircraft to their assigned altitude, while, at the same time, ensuring that the aircraft is properly separated from all other aircraft in its immediate area. Additionally, the aircraft must be placed in a flow consistent with the aircraft's route of flight. This effort is complicated by crossing traffic, severe weather, special missions that require large airspace allocations, and traffic density. When the aircraft approaches its destination, the centre is responsible for issuing instructions to pilots so that they will meet altitude restrictions by specific points, as well as providing many destination airports with a traffic flow, which prohibits all of the arrivals being 'bunched together'. These 'flow restrictions' often begin in the middle of the route, as controllers will position aircraft landing in the same destination so that when the aircraft are close to their destination they are sequenced.
As an aircraft reaches the boundary of a centre's control area, it is 'handed off' or 'handed over' to the next area control centre. In some cases, this 'hand-off' process involves a transfer of identification and details between controllers so that air traffic control services can be provided in a seamless manner; in other cases, local agreements may allow 'silent handovers', such that the receiving centre does not require any co-ordination if traffic is presented in an agreed manner. After the hand-off, the aircraft is given a frequency change, and its pilot begins talking to the next controller. This process continues until the aircraft is handed off to a terminal controller ('approach').
ERAM
The En Route Automation Modernization (ERAM) system architecture replaces the En Route Host computer system and its backup. ERAM provides all of today's functionality and:
Adds new capabilities needed to support the evolution of US National Airspace System.
Improves information security and streamlines traffic flow at US international borders.
Processes flight radar data.
Provides communications support.
Generates display data to air traffic controllers.
The display system provides real-time electronic aeronautical information and efficient data management.
Provides a fully functional backup system, precluding the need to restrict operations in the event of a primary failure.
The backup system provides the National Transportation Safety Board-recommended safety alerts, altitude warnings and conflict alerts.
Improves surveillance by using a greater number and variety of surveillance sources.
Detects and alerts air traffic controllers when aircraft are flying too close together for both safety and long term planning.
ERAM simultaneously supports many operating modes and complex airspace configurations, driven by thousands of users who want to use the airspace differently.
Allows more radars and flights than the old Host Computer System which ERAM replaces.