Self-separation

Last updated

Aircraft self-separation is the capability of an aircraft maintaining acceptably safe separation from other aircraft without following instructions or guidance from a referee agent for this purpose, such as air traffic control. In its simplest forms, it can be described by the concept of see and avoid, [1] in the case of human-piloted aircraft, or sense and avoid, [2] in the case of non-human piloted aircraft (such as UAVs). However, because of several factors such as weather, instrument flight rules and air traffic complexity, the self-separation capability involves other elements and aspects such as rules of the air, [3] communication technologies and protocols, air traffic management and others.

Contents

Context and historical background

Pilots of modern aircraft cannot rely only on visual abilities and piloting skills to maintain acceptably safe separation from other aircraft, thus a considerable proportion of contemporary flights are performed under instrument flight rules with the responsibility for separation belonging to air traffic control (ATC). However, as the air traffic growth in the end of the 20th century and in the beginning of the 21st [4] [5] [6] [7] is straining the ATC capacity, and pilot shortages become an ongoing issues, researchers on aviation and air transport are trying to propose operational and technological improvements in order to cope with this strain, one of which is self-separation. [8]

Self-separation started being considered as a potentially feasible operational concept within the Free Flight initiative. [9] Its key technological enabler is automatic dependent surveillance-broadcast (ADS-B), in which aircraft spontaneously transmit periodic position and state reports, including absolute horizontal position information, which is not used as information source for the pre-existing Traffic Collision Avoidance System (TCAS). In relation to the current implementations of TCAS, [10] which is intended only for collision avoidance, self-separation requires a leap in processing logic, time anticipation and procedure changes. Its feasibility is dependent on confidence in automation and its co-existence with the human role in the cockpit. Some studies have been conducted to assess this relationship, [11] [12] and the results show that the concept is well acceptable from the pilot point of view without imposing unreasonable workload.

An aligned but less radical and more implementable approach was later proposed and named as Distributed Air-Ground Traffic Management (DAG-TM), [13] keeping ATC still with a significant role, but allowing more freedom in en-route airspace. [14] Besides, other relevant aspects in a wider context have been studied in the Mediterranean Free Flight project [15] [16] (MFF) which had, as one of the main conclusions, that self-separation would be overall beneficial, but it should have to be limited to low- or medium-density airspace. [17]

Since the beginning of the association between self-separation and ADS-B, it has been also associated with another technical concept called Airborne Separation Assistance System [18] (ASAS) which, in short words, performs the core logic of Self-separation and other related applications. With this association, the concept of aircraft Self-separation in the full technological and operational context is more clearly distinguishable from the already cited see and avoid and sense and avoid basic concepts. ASAS was an assumption in the MFF project and also in subsequent studies such as the series from Consiglio et al., [19] [20] [21] [22] which went deeper in the human factor aspects and set the foundations for separating strategic and tactical conflict management processes in self-separation.

Other projects provided complementary contributions, such as the Advanced Safe Separation Technologies and Algorithms [23] (ASSTAR), which carried out performance, safety and cost-benefit analyses for ASAS applications, including a limited version of Self-separation, resulting in positive findings. Based on the above-mentioned and other studies, ASAS-based self-separation has been selected as one of the goals to be pursued by major development programs in air traffic management, such as Single European Sky ATM Research & Development (SESAR) [24] [25] and the U.S. Next Generation Air Transportation System [26] (NextGen), even if limited to certain conditions and airspaces.

Recent developments

More recently, the iFly project [27] defined a new concept of operations of self-separation in higher density airspace, based on the works described above, and evaluated it quantitatively using advanced stochastic simulation methods. [28] The results obtained from these studies indicate that self-separation can be safely used in an airspace with thrice the density of European en-route airspace as of in the year of 2005, if the ADS-B dependability level improves by a factor of five or if the TCAS dependability improves by the same factor.

Outstanding issues

Some of the most relevant issues to be solved for Self-separation are:

Although these topics have been researched and there are some solutions proposed for them, the complexity of the problem have prevented to achieve definitive responses.

Related Research Articles

<span class="mw-page-title-main">Avionics</span> Electronic systems used on aircraft

Avionics are the electronic systems used on aircraft. 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.

<span class="mw-page-title-main">Air traffic control</span> Service to direct pilots of aircraft

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 is to prevent collisions, organise and expedite the flow of traffic in the air, and provide information and other support for pilots.

Free flight is a developing air traffic control method that uses no centralized control. Instead, parts of airspace are reserved dynamically and automatically in a distributed way using computer communication to ensure the required separation between aircraft. This new system may be implemented into the U.S. air traffic control system in the next decade. Its potential impact on the operations of the national airspace system is disputed, however.

<span class="mw-page-title-main">Flight level</span> Measure in aviation

In aviation, a flight level (FL) is an aircraft's altitude as determined by a pressure altimeter using the International Standard Atmosphere. It is expressed in hundreds of feet or metres. The altimeter setting used is the ISA surface pressure of 1013 hPa or (29.92 inHg). The actual surface pressure may vary from this at different locations and times. Therefore, by using a standard pressure setting, every aircraft has the same altimeter setting, and vertical clearance can be maintained.

<span class="mw-page-title-main">2002 Überlingen mid-air collision</span> Fatal collision over Germany (July 2002)

On 1 July 2002, BALBashkirian Airlines Flight 2937, a Tupolev Tu-154 passenger jet, and DHL International Aviation ME Flight 611, a Boeing 757 cargo jet, collided in mid-air over Überlingen, a southern German town on Lake Constance, near the Swiss border. All of the passengers and crew aboard both planes were killed, resulting in a total death toll of 71.

<span class="mw-page-title-main">Traffic collision avoidance system</span> Aircraft collision avoidance system

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.

<span class="mw-page-title-main">ENAIRE</span> Spanish air navigation manager.

ENAIRE is the air navigation manager in Spain, certified for the provision of enroute, approach and aerodrome control services. As a public corporate entity attached to the Spanish Ministry of Public Works, it is responsible for air traffic control, aeronautical information and the communication, navigation and surveillance networks so air companies and their aircraft can fly safely and in an organised format within Spanish airspace.

<span class="mw-page-title-main">Eurocontrol</span> European air traffic organisation

The European Organisation for the Safety of Air Navigation, commonly known as Eurocontrol, is an international organisation working to achieve safe and seamless air traffic management across Europe. Founded in 1963, Eurocontrol currently has 41 member states with headquarters in Brussels, Belgium. It has several local sites as well, including an Innovation Hub in Brétigny-sur-Orge, France, the Aviation Learning Centre (ALC) in Luxembourg, and the Maastricht Upper Area Control Centre (MUAC) in Maastricht, the Netherlands. The organisation employs approximately two thousand people, and operates with an annual budget in excess of half a billion euros.

<span class="mw-page-title-main">Airborne collision avoidance system</span> Avionics system to avoid aircraft collision

An airborne collision avoidance system 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 recommends 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. 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.

A flight information service (FIS) is a form of air traffic service which is available to any aircraft within a flight information region (FIR), as agreed internationally by ICAO.

<span class="mw-page-title-main">Allegheny Airlines Flight 853</span> 1969 mid-air collision

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.

<span class="mw-page-title-main">Mid-air collision</span> Aviation accident where two or more aircraft come into contact during flight

In aviation, a mid-air collision is an accident in which two or more aircraft come into unplanned contact during flight. Owing to the relatively high velocities involved and the likelihood of subsequent impact with the ground or sea, very severe damage or the total destruction of at least one of the aircraft usually results. For this reason, accidents involving mid-air collisions especially during cruise frequently result in very few survivors or, more often, a total lack thereof. This is especially when the accident involves jet aircraft.

System Wide Information Management (SWIM) is a global Air Traffic Management (ATM) industry initiative to harmonize the exchange of Aeronautical, Weather and Flight information for all Airspace Users and Stakeholders. SWIM is an integral part of the International Civil Aviation Organization (ICAO) Global Air Navigation Plan (GANP). The GANP defines 4 Performance Improvement Areas (PIA), SWIM resides in PIA 2: Globally interoperable systems and data, where its implementation is further defined in Aviation System Block Upgrades (ASBU) B1-SWIM and B2-SWIM. ASBU B1-SWIM defines SWIM as a “a net-centric operation where the air traffic management (ATM) network is considered as a series of nodes, including the aircraft, providing or using information.” it goes on to say “The sharing of information of the required quality and timeliness in a secure environment is an essential enabler to the ATM target concept.”

Controller–pilot data link communications (CPDLC), also referred to as controller pilot data link (CPDL), is a method by which air traffic controllers can communicate with pilots over a datalink system.

<span class="mw-page-title-main">Separation (aeronautics)</span> Concept for keeping aircraft safe distances apart

In air traffic control, separation is the name for the concept of keeping an aircraft outside a minimum distance from another aircraft to reduce the risk of those aircraft colliding, as well as prevent accidents due to secondary factors, such as wake turbulence. Separation can also apply to terrain, obstacles, and controlled airspace, wherein an aircraft must stay at a minimum distance from a block of airspace; as an example, all aircraft must be approved by the controller who "owns" the airspace before the aircraft is approved to enter that sector.

Short-term conflict alert (STCA) is an automated warning system for air traffic controllers (ATCO). It is a ground-based safety net intended to assist the controller in preventing collision between aircraft by generating, in a timely manner, an alert of a potential or actual infringement of separation minima.

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.

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.

<span class="mw-page-title-main">Automatic Dependent Surveillance–Broadcast</span> Aircraft surveillance technology

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 from other aircraft to activate its transmissions. ADS-B can also receive 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.

Single European Sky ATM Research (SESAR) is a collaborative project to completely overhaul European airspace and its air traffic management (ATM). The actual program is managed by the SESAR Joint Undertaking as a public–private partnership (PPP).

References

  1. ↑ "See and Avoid, Skybrary". Archived from the original on 2021-11-15. Retrieved 2011-06-11.
  2. ↑ "Rosenkrans, W. "Detect, Sense and Avoid". FlightTech, pp. 24-29, July 2008" (PDF). Archived (PDF) from the original on 2018-05-16. Retrieved 2011-06-11.
  3. ↑ Rules of the Air, Annex 2 to the Convention on International Civil Aviation, ICAO.
  4. ↑ "Long-term Forecast of Flight Movements up to 2030". Eurocontrol. 17 December 2010. Retrieved 20 September 2024.
  5. ↑ The world of Civil Aviation 2003-2006. ICAO Circular 307 AT/129, 2005
  6. ↑ "Air Transport, Air traffic growth trends and forecasts" (PDF). UNESCAP. Archived from the original (PDF) on 2012-09-24.
  7. ↑ "FAA Aerospace Forecast Fiscal Years 2010-2030" (PDF). Archived (PDF) from the original on 2022-04-23. Retrieved 2019-10-30.
  8. ↑ "Airline Pilot Hiring Outlook and Career Information / ATP Flight School". atpflightschool.com. Archived from the original on 2023-11-10. Retrieved 2023-11-10.
  9. ↑ RTCA Task Force 3 Final Report on Free Flight Implementation. October, 1995
  10. ↑ "Federal Aviation Administration - Home Page – TCAS". Archived from the original on 2011-07-21. Retrieved 2011-06-14.
  11. ↑ "NLR Free Flight with Airborne Separation". Archived from the original on 2012-03-25. Retrieved 2011-06-14.
  12. ↑ D. R. Schleicher; et al. (30 March 2001). "Free Flight Simulation Infrastructure Fiscal Year 2000 Final Report" (PDF). Seagull Technology. Archived from the original (PDF) on 27 September 2011. Retrieved 14 June 2011.
  13. ↑ NASA, Concept definition for distributed air-/ground traffic management (DAG-TM), Version 1.0, Advanced Air Transportation Technologies project, Aviation System Capacity Program, National Aeronautics and Space Administration, NASA, 1999
  14. ↑ NASA. DAG-TM Concept element 5 en-route free maneuvering for user-preferred separation assurance and local TFM conformance operational concept description, AATT Project Milestone 8.503.10, NASA Airspace Systems Program Office, Washington D.C., 2004.
  15. ↑ "Search". Archived from the original on 2021-02-25. Retrieved 2011-06-14.
  16. ↑ http://www.medff.it Archived 2005-04-02 at the Wayback Machine
  17. ↑ Barff, Andy (2006-04-04). "Mediterranean Free Flight: Key Results". Rome: Eurocontrol. Archived from the original on 2016-03-03. Retrieved 2011-06-14.N.B: Direct download!
  18. ↑ "Airborne Separation Assurance Systems (ASAS) - SKYbrary Aviation Safety". Archived from the original on 2021-11-04. Retrieved 2011-06-14.
  19. ↑ M. Consiglio, S. Hoadley, D. Wing and B. Baxley, Safety Performance of Airborne Separation: Preliminary Baseline Testing, Proc. 7th AIAA ATIO Conf., Belfast, Northern Ireland, 2007
  20. ↑ M. Consiglio, S. Hoadley, D. Wing, B. Baxley and D. Allen, Impact of Pilot Delay and Non-Responsiveness on the Safety Performance of Airborne Separation, Proc. 8th AIAA ATIO Conf., September 2008
  21. ↑ M. Consiglio, S. Hoadley and B.D. Allen, Estimation of Separation Buffers for Wind-Prediction Error in an Airborne Separation Assistance System, Proc. USA/Europe ATM Seminar, Nappa, CA, 2009
  22. ↑ M.C. Consiglio, S.R. Wilson, J. Sturdy, J.L. Murdoch, D.J. Wing, Human in the loop simulation measures of pilot response delay in a Self-separation concept of operations, Proc. 27th Int. Congress of the Aeronautical Sciences (ICAS 2010), 2010
  23. ↑ "ASSTAR Home Page". Archived from the original on 2011-06-24. Retrieved 2011-06-14.
  24. ↑ "SESAR and Research | EUROCONTROL". Archived from the original on 2011-06-12. Retrieved 2011-06-14.
  25. ↑ "SESAR WP4 Projects". Archived from the original on 2012-05-06. Retrieved 2012-05-11.
  26. ↑ "Next Generation Air Transportation System (NextGen)". FAA. Archived from the original on 2022-08-11.
  27. ↑ "IFly Web-site". Archived from the original on 2022-08-06. Retrieved 2011-06-10.
  28. ↑ "H.A.P. Blom, G.J. Bakker, Safety of advanced airborne self-separation under very high en-route traffic demand, SESAR Innovation Days, 2011" (PDF). Archived from the original (PDF) on 2016-03-04. Retrieved 2012-05-11.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.