Air traffic control (ATC) is a service provided by ground-based air traffic controllers who direct aircraft on the ground and through a given section of 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 aviation, distance measuring equipment (DME) is a radio navigation technology that measures the slant range (distance) between an aircraft and a ground station by timing the propagation delay of radio signals in the frequency band between 960 and 1215 megahertz (MHz). Line-of-visibility between the aircraft and ground station is required. An interrogator (airborne) initiates an exchange by transmitting a pulse pair, on an assigned 'channel', to the transponder ground station. The channel assignment specifies the carrier frequency and the spacing between the pulses. After a known delay, the transponder replies by transmitting a pulse pair on a frequency that is offset from the interrogation frequency by 63 MHz and having specified separation.
A traffic collision avoidance system, also known as a traffic alert and collision avoidance system, is an aircraft collision avoidance system designed to reduce the incidence of mid-air collision (MAC) 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 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. ACAS/TCAS is based on secondary surveillance radar (SSR) transponder signals, but operates independently of ground-based equipment to provide advice to the pilot on potentially conflicting aircraft.
A transponder landing system (TLS) is an all-weather, precision landing system that uses existing airborne transponder and instrument landing system (ILS) equipment to create a precision approach at a location where an ILS would normally not be available.
Allegheny Airlines Flight 853 was a regularly scheduled Allegheny Airlines flight from Boston, Massachusetts, to St. Louis, Missouri, with stops in Baltimore, Maryland, Cincinnati, Ohio, and Indianapolis, Indiana. On September 9, 1969, the aircraft serving the flight, a McDonnell Douglas DC-9, collided in mid-air with a Piper PA-28 light aircraft near Fairland, Indiana. The DC-9 was carrying 78 passengers and 4 crew members, and 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.
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. 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.
Saab Sensis Corporation is a technology company based in East Syracuse, New York and is a subsidiary of Saab Group. Saab Sensis, formerly Sensis Corporation, was acquired by Saab Group in 2011. Following the acquisition, Saab consolidated its U.S. defense businesses under a new U.S.-based company named Saab Defense and Security USA (SDAS) leaving Saab Sensis to focus on air traffic solutions. Today, Saab Sensis leads Saab's global Air Traffic Management business with primary offices in Australia, the Netherlands, Sweden, and the U.S.
Runway Status Lights (RWSL) are a visual alerting system installed in some airport taxiways and runways for the purpose of collision-avoidance. When illuminated, red high-intensity LEDs indicate the presence of another vehicle either departing, occupying, or landing on an active runway. RWSL systems are fully-automated and intended to alert aircrews and ground vehicle operators of a potential runway incursion hazard. They operate as an additional layer of safety, independent of human-issued air traffic control clearances.
A transponder is an electronic device that produces a response when it receives a radio-frequency interrogation. Aircraft have transponders to assist in identifying them on air traffic control radar. Collision avoidance systems have been developed to use transponder transmissions as a means of detecting aircraft at risk of colliding with each other.
An equipment code describes the communication (COM), navigation (NAV), approach aids and surveillance transponder equipment on board an aircraft. These alphabetic codes are used on FAA and ICAO flight plan forms to aid Flight service station (FSS) personnel in their handling of aircraft.
A runway incursion is an aviation incident involving improper positioning of vehicles or people on any airport runway or its protected area. When an incursion involves an active runway being used by arriving or departing aircraft, the potential for a collision hazard or Instrument Landing System (ILS) interference can exist. At present, various runway safety technologies and processes are commonly employed to reduce the risk and potential consequences of such an event.
The Capstone Program was a United States government-funded aviation safety program for the state of Alaska, primarily focusing on rural areas of the state. This joint effort – between the Federal Aviation Administration (FAA), the Alaska Pilot's Association, commercial operators, the University of Alaska, MITRE Corporation, some avionics manufacturers and individual pilots – cut the accident rate in the eastern part of Alaska by around 40%.
The 2007 San Francisco International Airport runway incursion occurred around 1:36 p.m. PDT on May 26, 2007, when SkyWest Airlines Flight 5741, an Embraer EMB 120 Brasilia turboprop aircraft, nearly collided with Republic Airways Flight 4912, an Embraer 170 Regional Jet, at the intersection of Runways 1L and 28R at San Francisco International Airport (SFO).
The Next Generation Air Transportation System (NextGen) is an ongoing United States Federal Aviation Administration (FAA) project to modernize the National Airspace System (NAS). The FAA began work on NextGen improvements in 2007 and plans to finish the final implementation segment by 2030. The goals of the modernization include using new technologies and procedures to increase the safety, efficiency, capacity, access, flexibility, predictability, and resilience of the NAS while reducing the environmental impact of aviation.
Common ARTS is an air traffic control computer system that air traffic controllers use to track aircraft.
Automatic Dependent Surveillance–Broadcast (ADS-B) is an aviation surveillance technology and form of Electronic Conspicuity in which an aircraft determines its position via satellite navigation or other sensors and periodically broadcasts its position and other related data, enabling it to be tracked. The information can be received by air traffic control ground-based or satellite-based receivers as a replacement for secondary surveillance radar (SSR). Unlike SSR ADS-B does not require an interrogation signal from the ground or other aircraft to activate its transmissions. ADS-B can also received point-to-point by other nearby equipped "ADS-B In" equipped aircraft to provide traffic situational awareness and support self-separation. ADS-B is "automatic" in that it requires no pilot or external input to trigger its transmissions. It is "dependent" in that it depends on data from the aircraft's navigation system to provide the transmitted data.
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.
Runway safety is concerned with reducing harm that could occur on an aircraft runway. Safety means avoiding incorrect presence (incursion) of aircraft, inappropriate exits (excursion) and use of the wrong runway due to confusion. The runway condition is a runway's current status due to meteorological conditions and air safety.
On July 7, 2017, an Airbus A320-211 operating as Air Canada Flight 759 was nearly involved in an accident at San Francisco International Airport in San Mateo County, California, United States. The flight, which originated at Toronto Pearson International Airport, had been cleared by air traffic control to land on runway 28R and was on final approach to land on that runway; however, instead of lining up with the runway, the aircraft had lined up with the parallel taxiway, on which four fully loaded and fueled passenger airplanes were stopped awaiting takeoff clearance. The flight crew initiated a go-around prior to landing, after which it landed without further incident. The aircraft on the taxiway departed for their intended destinations without further incident. The subsequent investigation by the National Transportation Safety Board (NTSB) determined that the Air Canada airplane descended to 59 feet (18 m) above the ground before it began its climb, and that it missed colliding with one of the aircraft on the taxiway by 14 feet (4.3 m).
Airway Transportation Systems Specialists', also known as (ATSSs; FV-2101) are Systems Electronics Technicians assigned to the Technical Operations (TechOps) section of the Federal Aviation Administration's Air Traffic Organization (ATO). Airway Transportation Systems Specialists possess theoretical and practical knowledge in electronic theory and characteristics, functions, operations, and capabilities of a variety of National Airspace System (NAS) systems. Airway Transportation Systems Specialists ensure the safety and efficiency of the NAS by performing preventive maintenance, corrective maintenance, and system modifications of air traffic control systems at ATCTs, TRACONs, and ARTCCs throughout the United States of America and its territories. ATSS generally possesses years of experience in a variety of U.S. National Airspace System (NAS) systems. Airway Transportation Systems Specialists are responsible for the maintenance, operation, fabrication, installation, and management of the technical infrastructure of the National Airspace System. Airway Transportation Systems Specialists work at different Systems Support Centers (SSCs) in the United States. Airway Transportation Systems Specialists install, maintain, repair, operate, and monitor hardware and software to ensure they work as designed. ATSS certifies equipment and services to ensure safe and efficient flight operations throughout NAS. The FAA workforce currently includes 5,200 ATSS nationwide.
