An airborne collision avoidance system (ACAS, usually pronounced as ay-kas) operates independently of ground-based equipment and air traffic control in warning pilots of the presence of other aircraft that may present a threat of collision. If the risk of collision is imminent, the system initiates a maneuver that will reduce the risk of collision. ACAS standards and recommended practices are mainly defined in annex 10, volume IV, of the Convention on International Civil Aviation.[1] Much of the technology being applied to both military and general aviation today has been undergoing development by NASA and other partners since the 1980s.[2]
The U.S. Air Force's F-16D Ground Collision Avoidance Technology (GCAT) aircraft.
A distinction is increasingly being made between ACAS and ASAS (airborne separation assurance system). ACAS is being used to describe short-range systems intended to prevent actual metal-on-metal collisions. In contrast, ASAS is being used to describe longer-range systems used to maintain standard en route separation between aircraft (5 nautical miles (9.3 km) horizontal and 1,000 feet (300 m) vertical).[3]
As of 1973, the United States Federal Aviation Administration (FAA) standard for transponder minimal operational performance, Technical Standard Order (TSO) C74c, contained errors which caused compatibility problems with air traffic control radar beacon system (ATCRBS) radar and Traffic Collision Avoidance System (TCAS) abilities to detect aircraft transponders. First called "The Terra Problem", there have since been individual FAA Airworthiness Directives issued against various transponder manufacturers in an attempt to repair the operational deficiencies, to enable newer radars and TCAS systems to operate. Unfortunately, the defect[clarification needed] is in the TSO, and the individual corrective actions to transponders have led to significant differences in the logical behavior of transponders by make and mark, as proven by an FAA study of in-situ transponders.[citation needed] In 2009, a new version, TSO C74d[5] was defined with tighter technical requirements.[citation needed]
AIS-P (ACAS)[clarification needed] is a modification which both corrects the transponder deficiencies (the transponder will respond to all varieties of radar and TCAS), then adds an Automatic Independent Surveillance with Privacy augmentation. The AIS-P protocol does not suffer from the saturation issue in high density traffic, does not interfere with the Air Traffic Control (ATC) radar system or TCAS, and conforms to the internationally approved Mode S data packet standard.[citation needed] It awaits member country submission to the ICAO as a requested approval.[citation needed]
Other collision avoidance systems
Modern aircraft can use several types of collision avoidance systems to prevent unintentional contact with other aircraft, obstacles, or the ground.
Aircraft collision avoidance
Some of the systems are designed to avoid collisions with other aircraft and UAVs. They are referred to as "electronic conspicuity" by the UK CAA.[6]
Airborne radar can detect the relative location of other aircraft, and has been in military use since World War II, when it was introduced to help night fighters (such as the de Havilland Mosquito and Messerschmitt Bf 110) locate bombers. While larger civil aircraft carry weather radar, sensitive anti-collision radar is rare in non-military aircraft.
Traffic collision avoidance system (TCAS), the implementation of ACAS,[4]: 14 actively interrogates the transponders of other aircraft and negotiates collision-avoidance tactics with them in case of a threat. TCAS systems are relatively expensive, and tend to appear only on larger aircraft. They are effective in avoiding collisions only with other aircraft that are equipped with functioning transponders with altitude reporting.
Small PCAS device for use in light aircraft.
a Portable Collision Avoidance System (PCAS) is a less expensive, passive version of TCAS designed for general aviation use. PCAS systems do not actively interrogate the transponders of other aircraft, but listen passively to responses from other interrogations. PCAS is subject to the same limitations as TCAS, although the cost for PCAS is significantly less.
FLARM is a small-size, low-power device (commonly used in gliders or other light aircraft) which broadcasts its own position and speed vector (as obtained with an integrated GPS) over a license-free ISM band radio transmission. At the same time it listens to other devices based on the same standard. Intelligent motion prediction algorithms predict short-term conflicts and warn the pilot accordingly by acoustical and visual means. FLARM incorporates a high-precision WAAS 16-channel GPS receiver and an integrated low-power radio transceiver. Static obstacles are included in FLARM's database. No warning is given if an aircraft does not contain an additional FLARM device.
a Terrain awareness and warning system (TAWS) uses a digital terrain map, together with position information from a navigation system such as GPS, to predict whether the aircraft's current flight path could put it in conflict with obstacles such as mountains or high towers, that would not be detected by GPWS (which uses the ground elevation directly beneath the aircraft). One of the best examples of this type of technology is the Auto-GCAS (Automatic Ground Collision Avoidance System) and PARS (Pilot Activated Recovery System) that was installed on the entire USAF fleet of F-16's in 2014.[7]
Synthetic vision provides pilots with a computer-generated simulation of their outside environment for use in low or zero-visibility situations. Information used to present warnings is often taken from GPS, INS, or gyroscopic sensors.
^. Archived from the original on 2010-04-21. Retrieved 2010-04-18.
^"NASA-Pioneered Automatic Ground-Collision Avoidance System Operational". NASA website. Retrieved 8 Oct 2014.
^[Hoekstra, J.M. (2002). Free flight with airborne separation assurance. Report No. NLR-TP-2002-170. National Aerospace Laboratory NLR.]
^ abAirborne Collision Avoidance System (ACAS) guide(PDF). Eurocontrol. March 2022.
^"TSO C74d Air Traffic Control Radar Beacon System (ATCRBS) Airborne Equipment" (PDF). Federal Aviation Administration.
^"Electronic conspicuity devices". UK CAA. Retrieved 13 September 2022.
^Jedick, Rocky (14 December 2014). "Ground Collision Avoidance System". Go Flight Medicine. Retrieved 16 Dec 2014.
External links
ACAS on Skybrary
FLARM
February 14, 2023
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This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Airborne collision avoidance system news newspapers books scholar JSTOR January 2008 Learn how and when to remove this template message An airborne collision avoidance system ACAS usually pronounced as ay kas operates independently of ground based equipment and air traffic control in warning pilots of the presence of other aircraft that may present a threat of collision If the risk of collision is imminent the system initiates a maneuver that will reduce the risk of collision ACAS standards and recommended practices are mainly defined in annex 10 volume IV of the Convention on International Civil Aviation 1 Much of the technology being applied to both military and general aviation today has been undergoing development by NASA and other partners since the 1980s 2 The U S Air Force s F 16D Ground Collision Avoidance Technology GCAT aircraft A distinction is increasingly being made between ACAS and ASAS airborne separation assurance system ACAS is being used to describe short range systems intended to prevent actual metal on metal collisions In contrast ASAS is being used to describe longer range systems used to maintain standard en route separation between aircraft 5 nautical miles 9 3 km horizontal and 1 000 feet 300 m vertical 3 Contents 1 Implementations 2 Other collision avoidance systems 2 1 Aircraft collision avoidance 2 2 Terrain collision avoidance 3 See also 4 References 5 External linksImplementations EditSee also Traffic collision avoidance system Versions As of 2022 the only implementations that meets the ACAS II standards set by ICAO are Versions 7 0 and 7 1 of TCAS II Traffic Collision Avoidance System produced by Garmin Rockwell Collins Honeywell and ACSS Aviation Communication amp Surveillance Systems an L 3 Communications and Thales Avionics company 4 14 16 As of 1973 the United States Federal Aviation Administration FAA standard for transponder minimal operational performance Technical Standard Order TSO C74c contained errors which caused compatibility problems with air traffic control radar beacon system ATCRBS radar and Traffic Collision Avoidance System TCAS abilities to detect aircraft transponders First called The Terra Problem there have since been individual FAA Airworthiness Directives issued against various transponder manufacturers in an attempt to repair the operational deficiencies to enable newer radars and TCAS systems to operate Unfortunately the defect clarification needed is in the TSO and the individual corrective actions to transponders have led to significant differences in the logical behavior of transponders by make and mark as proven by an FAA study of in situ transponders citation needed In 2009 a new version TSO C74d 5 was defined with tighter technical requirements citation needed AIS P ACAS clarification needed is a modification which both corrects the transponder deficiencies the transponder will respond to all varieties of radar and TCAS then adds an Automatic Independent Surveillance with Privacy augmentation The AIS P protocol does not suffer from the saturation issue in high density traffic does not interfere with the Air Traffic Control ATC radar system or TCAS and conforms to the internationally approved Mode S data packet standard citation needed It awaits member country submission to the ICAO as a requested approval citation needed Other collision avoidance systems EditModern aircraft can use several types of collision avoidance systems to prevent unintentional contact with other aircraft obstacles or the ground Aircraft collision avoidance Edit Some of the systems are designed to avoid collisions with other aircraft and UAVs They are referred to as electronic conspicuity by the UK CAA 6 Airborne radar can detect the relative location of other aircraft and has been in military use since World War II when it was introduced to help night fighters such as the de Havilland Mosquito and Messerschmitt Bf 110 locate bombers While larger civil aircraft carry weather radar sensitive anti collision radar is rare in non military aircraft Traffic collision avoidance system TCAS the implementation of ACAS 4 14 actively interrogates the transponders of other aircraft and negotiates collision avoidance tactics with them in case of a threat TCAS systems are relatively expensive and tend to appear only on larger aircraft They are effective in avoiding collisions only with other aircraft that are equipped with functioning transponders with altitude reporting Small PCAS device for use in light aircraft a Portable Collision Avoidance System PCAS is a less expensive passive version of TCAS designed for general aviation use PCAS systems do not actively interrogate the transponders of other aircraft but listen passively to responses from other interrogations PCAS is subject to the same limitations as TCAS although the cost for PCAS is significantly less FLARM is a small size low power device commonly used in gliders or other light aircraft which broadcasts its own position and speed vector as obtained with an integrated GPS over a license free ISM band radio transmission At the same time it listens to other devices based on the same standard Intelligent motion prediction algorithms predict short term conflicts and warn the pilot accordingly by acoustical and visual means FLARM incorporates a high precision WAAS 16 channel GPS receiver and an integrated low power radio transceiver Static obstacles are included in FLARM s database No warning is given if an aircraft does not contain an additional FLARM device Terrain collision avoidance Edit a Ground proximity warning system GPWS or Ground collision warning system GCWS which uses a radar altimeter to detect proximity to the ground or unusual descent rates GPWS is common on civil airliners and larger general aviation aircraft a Terrain awareness and warning system TAWS uses a digital terrain map together with position information from a navigation system such as GPS to predict whether the aircraft s current flight path could put it in conflict with obstacles such as mountains or high towers that would not be detected by GPWS which uses the ground elevation directly beneath the aircraft One of the best examples of this type of technology is the Auto GCAS Automatic Ground Collision Avoidance System and PARS Pilot Activated Recovery System that was installed on the entire USAF fleet of F 16 s in 2014 7 Synthetic vision provides pilots with a computer generated simulation of their outside environment for use in low or zero visibility situations Information used to present warnings is often taken from GPS INS or gyroscopic sensors See also EditAcronyms and abbreviations in avionics Air traffic control Automatic dependent surveillance broadcast Avionics Collision avoidanceReferences Edit EUROCONTROL ACAS II ICAO Provisions Archived from the original on 2010 04 21 Retrieved 2010 04 18 NASA Pioneered Automatic Ground Collision Avoidance System Operational NASA website Retrieved 8 Oct 2014 Hoekstra J M 2002 Free flight with airborne separation assurance Report No NLR TP 2002 170 National Aerospace Laboratory NLR a b Airborne Collision Avoidance System ACAS guide PDF Eurocontrol March 2022 TSO C74d Air Traffic Control Radar Beacon System ATCRBS Airborne Equipment PDF Federal Aviation Administration Electronic conspicuity devices UK CAA Retrieved 13 September 2022 Jedick Rocky 14 December 2014 Ground Collision Avoidance System Go Flight Medicine Retrieved 16 Dec 2014 External links EditACAS on Skybrary FLARM Retrieved from https en wikipedia org w index php title Airborne collision avoidance system amp oldid 1117534351, wikipedia, wiki, book, books, library,
