An airport surveillance radar (ASR) is a radar system used at airports to detect and display the presence and position of aircraft in the terminal area, the airspace around airports. It is the main air traffic control system for the airspace around airports. At large airports it typically controls traffic within a radius of 60 miles (96 km) of the airport below an elevation of 25,000 feet. The sophisticated systems at large airports consist of two different radar systems, the primary and secondary surveillance radar. The primary radar typically consists of a large rotating parabolic antenna dish that sweeps a vertical fan-shaped beam of microwaves around the airspace surrounding the airport. It detects the position and range of aircraft by microwaves reflected back to the antenna from the aircraft's surface. In the US the primary radar operates at a frequency of 2.7 - 2.9 GHz in the S band with a peak radiated power of 25 kW and an average power of 2.1 kW. The secondary surveillance radar consists of a second rotating antenna, often mounted on the primary antenna, which interrogates the transponders of aircraft, which transmits a radio signal back containing the aircraft's identification, barometric altitude, and an emergency status code, which is displayed on the radar screen next to the return from the primary radar. It operates at a frequency of 1.03 - 1.09 GHz in the L band with peak power of 160 - 1500 W.
Radar is a detection system that uses radio waves to determine the range, angle, or velocity of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. A radar system consists of a transmitter producing electromagnetic waves in the radio or microwaves domain, a transmitting antenna, a receiving antenna and a receiver and processor to determine properties of the object(s). Radio waves from the transmitter reflect off the object and return to the receiver, giving information about the object's location and speed.
Air traffic control (ATC) is a service provided by ground-based air traffic controllers who direct aircraft on the ground and through controlled airspace, and can provide advisory services to aircraft in non-controlled airspace. The primary purpose of ATC worldwide is to prevent collisions, organize and expedite the flow of air traffic, and provide information and other support for pilots. In some countries, ATC plays a security or defensive role, or is operated by the military.
A parabolic antenna is an antenna that uses a parabolic reflector, a curved surface with the cross-sectional shape of a parabola, to direct the radio waves. The most common form is shaped like a dish and is popularly called a dish antenna or parabolic dish. The main advantage of a parabolic antenna is that it has high directivity. It functions similarly to a searchlight or flashlight reflector to direct the radio waves in a narrow beam, or receive radio waves from one particular direction only. Parabolic antennas have some of the highest gains, meaning that they can produce the narrowest beamwidths, of any antenna type. In order to achieve narrow beamwidths, the parabolic reflector must be much larger than the wavelength of the radio waves used, so parabolic antennas are used in the high frequency part of the radio spectrum, at UHF and microwave (SHF) frequencies, at which the wavelengths are small enough that conveniently-sized reflectors can be used.
The positions of the aircraft are displayed on a screen; at large airports on multiple screens in an operations room at the airport called in the US the Terminal Radar Approach Control (TRACON), monitored by air traffic controllers who direct the traffic by communicating with the aircraft pilots by radio. They are responsible for maintaining a safe and orderly flow of traffic and adequate aircraft separation to prevent midair collisions.
Air traffic controllers often abbreviated ATC are personnel responsible for the safe, orderly, and expeditious flow of air traffic in the global air traffic control system. Usually stationed in air traffic control centers and control towers on the ground, they monitor the position, speed, and altitude of aircraft in their assigned airspace visually and by radar, and give directions to the pilots by radio. The position of air traffic controller is one that requires highly specialized knowledge, skills, and abilities. Controllers apply separation rules to keep aircraft at a safe distance from each other in their area of responsibility and move all aircraft safely and efficiently through their assigned sector of airspace, as well as on the ground. Because controllers have an incredibly large responsibility while on duty and make countless real-time decisions on a daily basis, the ATC profession is consistently regarded around the world as one of the most mentally challenging careers, and can be notoriously stressful depending on many variables. Many controllers, however, would cite high salaries, and a very large, unique, and privileged degree of autonomy as major advantages of their jobs.
Due to its crucial safety mission, extreme uptime requirements, and need to be compatible with all the different types of aircraft and avionics systems, the design of airport surveillance radar is strictly controlled by government agencies. In the US the Federal Aviation Administration (FAA) is responsible for developing airport surveillance radar. All ASRs have the common requirements of detecting aircraft out to a range of 60 miles and an elevation of 25,000 feet. Upgrades are released in "generations" after careful testing:
Avionics are the electronic systems used on aircraft, artificial satellites, and spacecraft. Avionic systems include communications, navigation, the display and management of multiple systems, and the hundreds of systems that are fitted to aircraft to perform individual functions. These can be as simple as a searchlight for a police helicopter or as complicated as the tactical system for an airborne early warning platform. The term avionics is a portmanteau of the words aviation and electronics.
The Federal Aviation Administration (FAA) of the United States is a national authority with powers to regulate all aspects of civil aviation. These include the construction and operation of airports, air traffic management, the certification of personnel and aircraft, and the protection of U.S. assets during the launch or re-entry of commercial space vehicles.
These are older technology systems which will eventually be replaced. The final ASR-7 was located at Sawyer International Airport (formerly K. I. Sawyer Air Force Base) and was removed from service, being dismantled from atop the SAGE Building on January 22nd, 2019. It was replaced in 2018 with an ASR-8, which was mounted atop a free-standing tower located near the northwest end of the runway. There are approximately a dozen ASR-8s left in the USA with no scheduled replacement until at least 2025.
K. I. Sawyer Air Force Base is a decommissioned U.S. Air Force installation in Marquette County, Michigan, south of the city of Marquette. Near the center of Michigan's Upper Peninsula, the base operated for nearly forty years and closed in 1995. The county airport, Sawyer International, now occupies a portion of the base and has scheduled airline flights and some general aviation activity. The area of the former base is now an unincorporated community and a census-designated place for statistical purposes known as K. I. Sawyer AFB.
The Semi-Automatic Ground Environment (SAGE) was a system of large computers and associated networking equipment that coordinated data from many radar sites and processed it to produce a single unified image of the airspace over a wide area. SAGE directed and controlled the NORAD response to a Soviet air attack, operating in this role from the late 1950s into the 1980s. Its enormous computers and huge displays remain a part of cold war lore, and a common prop in movies such as Dr. Strangelove and Colossus.
The current generation of radar is the ASR-9, which was developed by Northrop/Grumman and first installed in 1989, with installation completing in 1995. Currently it is operating at 135 locations and is scheduled to continue in use until at least 2025. The ASR-9 was the first airport surveillance radar to detect weather and aircraft with the same beam and display them on the same screen. It has a digital Moving Target Detection (MTD) processor which uses doppler radar and a clutter map giving advanced ability to eliminate ground and weather clutter and track targets. It is theoretically capable of tracking a maximum of 700 aircraft simultaneously.
ASR-9 is an airport surveillance radar system admitted into the National Airspace System (NAS), to be utilized by the Federal Aviation Administration to monitor civilian and commercial air traffic within the United States. Developed by Westinghouse, ASR-9 was the first radar system to display air traffic, and weather conditions simultaneously. The ASR-9 is mainly intended to monitor and track aircraft below 25,000 ft and within forty to sixty nautical miles from the airport of operation. The ASR radar systems were widely used where an advanced radar system was needed, consisting of 135 different ASR-9 operating locations around the U.S. The FAA is currently working to upgrade the remaining ASR-9 radar sites to a modernized digital version known as the ASR-11.
A Doppler radar is a specialized radar that uses the Doppler effect to produce velocity data about objects at a distance. It does this by bouncing a microwave signal off a desired target and analyzing how the object's motion has altered the frequency of the returned signal. This variation gives direct and highly accurate measurements of the radial component of a target's velocity relative to the radar. Doppler radars are used in aviation, sounding satellites, Major League Baseball's StatCast system, meteorology, radar guns, radiology and healthcare, and bistatic radar.
The klystron tube transmitter operates in the S-band between 2.5-2.9 GHz in circular polarization with a peak power of 1.3 MW and a pulse duration of 1 μs and pulse repetition frequency between 325 to 1200 pps. It can be switched to a second reserve frequency if interference is encountered on the primary frequency. The receiver has the sensitivity to detect a radar cross-section of 1 meter2 at 111 km, and a range resolution of 450 feet. The antenna covers an elevation of 40° from the horizon with two feedhorns which create two stacked overlapping vertical lobes 4° apart; the lower beam transmits the outgoing pulse and is used to detect distant targets near the horizon, while the upper receive-only beam detects closer higher elevation aircraft with less ground clutter. The antenna has a gain of 34 dB, beamwidth of 5° in elevation and 1.4° in azimuth. It rotates at a rate of 12.5 RPM so the airspace is scanned every 4.8 seconds.
A klystron is a specialized linear-beam vacuum tube, invented in 1937 by American electrical engineers Russell and Sigurd Varian, which is used as an amplifier for high radio frequencies, from UHF up into the microwave range. Low-power klystrons are used as oscillators in terrestrial microwave relay communications links, while high-power klystrons are used as output tubes in UHF television transmitters, satellite communication, radar transmitters, and to generate the drive power for modern particle accelerators.
In electrodynamics, circular polarization of an electromagnetic wave is a polarization state in which, at each point, the electric field of the wave has a constant magnitude but its direction rotates with time at a steady rate in a plane perpendicular to the direction of the wave.
Radar cross-section (RCS) is a measure of how detectable an object is by radar. A larger RCS indicates that an object is more easily detected.
The electronics is dual-channel and fault tolerant. It has a remote monitoring and maintenance subsystem; if a fault occurs a built-in test detects and isolates the problem. Like all airport surveillance radars it has a backup diesel generator to continue operating during power outages.
The Digital Airport Surveillance Radar (DASR) is the new generation of fully digital radar that is being developed to replace the current analog systems. The US Air Force Electronics Systems Center, the US Federal Aviation Administration, US Army and the US Navy procured DASR systems to upgrade existing radar facilities for US Department of Defense (DoD) and civilian airfields. The DASR system detects aircraft position and weather conditions in the vicinity of civilian and military airfields. The civilian nomenclature for this radar is ASR-11. The ASR-11 will replace most ASR-7 and some ASR-8. The military nomenclature for the radar is AN/GPN-30. The older radars, some up to 20 years old, are being replaced to improve reliability, provide additional weather data, reduce maintenance cost, improve performance, and provide digital data to new digital automation systems for presentation on air traffic control displays.The Iraqi Air Force has received the DASR system.
ASR data is displayed on Automated Radar Terminal System (ARTS), Common Automated Radar Terminal System (CARTS), and Standard Terminal Automation Replacement System (STARS) display consoles in control towers and Terminal Radar Approach Control (TRACON) rooms, usually located at airports. CARTS will be replaced with STARS at all TRACONs during TAMR Phase 3 - Segment 1 as announced by the Federal Aviation Administration (FAA) in the Spring of 2011. All remaining ARTS (IIE) sites will be replaced with STARS during TAMR Phase 3 Segment 2 as announced by the FAA in the Spring of 2013.
The Standard Terminal Automation Replacement System (STARS) is a joint Federal Aviation Administration (FAA) and Department of Defense (DoD) program to replace Automated Radar Terminal Systems (ARTS) and other capacity-constrained, older technology systems at 172 FAA and up to 199 DoD terminal radar approach control facilities and associated towers.
STARS will be used by controllers, at facilities who already have it installed, to provide air traffic control (ATC) services to aircraft in terminal areas. Typical terminal area ATC services are defined as the area around airports where departing and arriving traffic are served. Functions include aircraft separation, weather advisories, and lower level control of air traffic. The system is designed to accommodate air traffic growth and the introduction of new automation functions which will improve the safety and efficiency of the US National Airspace System (NAS) as the legacy systems are replaced.
Airport Surveillance Radar is beginning to be supplemented by ADS-B Automatic dependent surveillance-broadcast in the US and other parts of the world. As of Spring 2011, ADS-B is currently operational and in use at the Philadelphia, PA TRACON and Louisville, KY TRACON. ADS-B is a GPS based technology that allows aircraft to transmit their GPS determined position to display systems as often as once per second, as opposed to once every 4 seconds for a short range radar, or once every 13 seconds for a slower rotating long range radar. The FAA is mandating that ADS-B be fully operational and available to the NAS by the year 2020. This will make possible the decommissioning of older radars in order to increase safety and cut costs. As of 2011, there is no definitive list of radars that will be decommissioned as a result of ADS-B implementation.
A traffic collision avoidance system or traffic alert and collision avoidance system is an aircraft collision avoidance system designed to reduce the incidence of mid-air collisions between aircraft. It monitors the airspace around an aircraft for other aircraft equipped with a corresponding active transponder, independent of air traffic control, and warns pilots of the presence of other transponder-equipped aircraft which may present a threat of mid-air collision (MAC). It is a type of airborne collision avoidance system mandated by the International Civil Aviation Organization to be fitted to all aircraft with a maximum take-off mass (MTOM) of over 5,700 kg (12,600 lb) or authorized to carry more than 19 passengers. CFR 14, Ch I, part 135 requires that TCAS I be installed for aircraft with 10-30 passengers and TCAS II for aircraft with more than 30 passengers.
The Air Route Surveillance Radar is used by the United States Air Force and the Federal Aviation Administration to control airspace within and around the borders of the United States.
Airport Surface Detection Equipment, Model X, or ASDE-X, is a runway-safety tool that enables air traffic controllers to detect potential runway conflicts by providing detailed coverage of movement on runways and taxiways. By collecting data from a variety of sources, ASDE-X is able to track vehicles and aircraft on airport surfaces and obtain identification information from aircraft transponders.
In air traffic control, an area control center (ACC), also known as a center or en-route center, is a facility responsible for controlling aircraft flying in a particular volume of airspace at high altitudes between airport approaches and departures. In the US, such a center is referred to as an air route traffic control center (ARTCC).
On September 9, 1969, Allegheny Airlines Flight 853, a McDonnell Douglas DC-9 passenger jet, collided in mid-air with a Piper PA-28 light aircraft near Fairland, Indiana, United States. The DC-9 was carrying 78 passengers and 4 crew members. The Piper was leased to a student pilot on a solo cross-country flight. All 83 occupants of both aircraft were killed in the accident and both aircraft were destroyed by the collision and ground impact.
ERAM is an FAA Air Traffic Control system designed to "allow faster processing of route requests and in flight route changes".
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 is intended to replace the Automated Radar Terminal System (ARTS). ARTS is still in use at many air traffic control facilities.
The Boston Consolidated TRACON (A90) is located in Merrimack, New Hampshire. BCT opened in 2004 after 8 years of development. The A90 function transferred to the new Boston Consolidated TRACON on February 22, 2004. The MHT function transferred over on March 7, 2004. Manchester TRACON used to be located at Manchester Airport below the old ATCT. Boston TRACON used to be located at the Logan International Airport Control Tower before being consolidated. The new facility is 63,000 square feet (5,900 m2). A Terminal Radar Approach Control, or TRACON, is responsible for descending airplanes from the ARTCC and lining them up for landing at their destination airport, as well as climbing departures before handing off to the ARTCC.
The Next Generation Air Transportation System (NextGen) is an ongoing modernization project of the United States' National Airspace System (NAS). The US Federal Aviation Administration (FAA) began work on NextGen improvements in 2007 and plans to have all major components in place by 2025.
The National Airspace System (NAS) is the airspace, navigation facilities and airports of the United States along with their associated information, services, rules, regulations, policies, procedures, personnel and equipment. It includes components shared jointly with the military. It is one of the most complex aviation systems in the world and services air travel in the United States and over large portions of the world's oceans.
Common ARTS is an air traffic control computer system that air traffic controllers use to track aircraft.
ASR-11 is a Digital Airport Surveillance Radar (DASR,) an advanced radar system utilized by the United States as the next generation of terminal air traffic control. The ASR-11 is an upgraded, advanced version of the previous ASR-9 radar. This next generation radar system has been developed through a joint effort by the Federal Aviation Administration, the Department of Defense and the United States Air Force, who took most of the lead development tasks.
The Air Traffic Organization (ATO) is America's air navigation service provider, as the operations arm of the Federal Aviation Administration. Its customers are commercial and private aviation and the military, and it employs more than 35,000 controllers, technicians, engineers and support workers.
Automatic dependent surveillance—broadcast (ADS–B) is a surveillance technology in which an aircraft determines its position via satellite navigation and periodically broadcasts it, enabling it to be tracked. The information can be received by air traffic control ground stations as a replacement for secondary surveillance radar, as no interrogation signal is needed from the ground. It can also be received by other aircraft to provide situational awareness and allow self-separation.
Anchorage Air Route Traffic Control Center (PAZA/ZAN) is located just outside the main gate of Joint Base Elmendorf-Richardson at 700 North Boniface Parkway in Anchorage, Alaska, United States. The Anchorage ARTCC is one of 22 Air Route Traffic Control Centers in the United States.
This is a list of the acronyms and abbreviations used in avionics.
Airport Surface Surveillance Capability (ASSC) is a runway-safety tool that displays aircraft and ground vehicles on the airport surface, as well as aircraft on approach and departure paths within a few miles of the airport. The tool allows air traffic controllers and air crew in cockpits equipped with Automatic Dependent Surveillance-Broadcast (ADS-B) to detect potential runway conflicts by providing detailed coverage of movement on runways and taxiways. By collecting and fusing data from a variety of sources, ASSC is able to track vehicles and aircraft on airport surfaces and obtain identification information from aircraft ADS-B transponders.
The Cape TRACON (K90) is located Joint Base Cape Cod, Massachusetts next to the airfield for Coast Guard Air Station Cape Cod. This radar approach facility is operated by the Federal Aviation Administration (FAA).