self-separation

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{{Cite web |url=https://www.eurocontrol.int/publication/long-term-forecast-flight-movements-2030 |title=Long-term Forecast of Flight Movements up to 2030 |date=17 December 2010 |publisher=Eurocontrol |access-date=20 September 2024}}The world of Civil Aviation 2003-2006. ICAO Circular 307 AT/129, 2005{{Cite web |url=http://www.unescap.org/ttdw/Publications/TPTS_pubs/pub_2307/pub_2307_ch12.pdf |title=Air Transport, Air traffic growth trends and forecasts |publisher=UNESCAP |archive-url=https://web.archive.org/web/20120924062725/http://www.unescap.org/ttdw/Publications/TPTS_pubs/pub_2307/pub_2307_ch12.pdf |archive-date=2012-09-24}}{{Cite web |url=https://www.faa.gov/data_research/aviation/aerospace_forecasts/2010-2030/media/2010%20Forecast%20Doc.pdf |title=FAA Aerospace Forecast Fiscal Years 2010-2030 |access-date=2019-10-30 |archive-date=2022-04-23 |archive-url=https://web.archive.org/web/20220423090243/http://www.faa.gov/data_research/aviation/aerospace_forecasts/2010-2030/media/2010%20Forecast%20Doc.pdf |url-status=live }} 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.{{Cite web |title=Airline Pilot Hiring Outlook and Career Information / ATP Flight School |url=https://atpflightschool.com/become-a-pilot/airline-career/pilot-hiring-outlook.html |access-date=2023-11-10 |website=atpflightschool.com |archive-date=2023-11-10 |archive-url=https://web.archive.org/web/20231110191044/https://atpflightschool.com/become-a-pilot/airline-career/pilot-hiring-outlook.html |url-status=live }}

Self-separation started being considered as a potentially feasible operational concept within the Free Flight initiative.RTCA Task Force 3 Final Report on Free Flight Implementation. October, 1995 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,{{Cite web |url=http://adsb.tc.faa.gov/TCAS.htm |title=Federal Aviation Administration - Home Page – TCAS |access-date=2011-06-14 |archive-url=https://web.archive.org/web/20110721040203/http://adsb.tc.faa.gov/TCAS.htm |archive-date=2011-07-21 |url-status=dead }} 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,{{cite web |url=http://www2.nlr.nl/public/hosted-sites/freeflight/main.htm |title=NLR Free Flight with Airborne Separation |accessdate=2011-06-14 |url-status=dead |archiveurl=https://web.archive.org/web/20120325171408/http://www2.nlr.nl/public/hosted-sites/freeflight/main.htm |archivedate=2012-03-25 }}{{cite web |url=http://www.asc.nasa.gov/aatt/rto/RTOFinal21.pdf |title=Free Flight Simulation Infrastructure Fiscal Year 2000 Final Report |author1=D. R. Schleicher |author2=P. C. Davis |author3=E. Wallace |author4=S. Shah |author5=S. Dorsky |author6=T. Mueller |author7=E. Jones |author8=J. Krozel |author9=G. J. Couluris |author10=D. Dow |display-authors=1 |publisher=Seagull Technology |date=30 March 2001 |access-date=14 June 2011 |url-status=dead |archive-url=https://web.archive.org/web/20110927183926/http://www.asc.nasa.gov/aatt/rto/RTOFinal21.pdf |archive-date=27 September 2011}} 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),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 keeping ATC still with a significant role, but allowing more freedom in en-route airspace.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. Besides, other relevant aspects in a wider context have been studied in the Mediterranean Free Flight project{{Cite web|url=http://www.eurocontrol.int/eec/public/standard_page/proj_MFF.html|title=Search|access-date=2011-06-14|archive-date=2021-02-25|archive-url=https://web.archive.org/web/20210225083708/https://www.eurocontrol.int/search?keywords=proj%20MFF&sort_by=search_api_relevance|url-status=dead}}http://www.medff.it {{webarchive|url=https://web.archive.org/web/20050402015652/http://www.medff.it/ |date=2005-04-02 }} (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.{{Cite web |url=http://www.asas-tn.org/workshops/2nd-asas-tn2-workshop/session-3-b/1_MFFresults.ppt |title=Mediterranean Free Flight: Key Results |date=2006-04-04 |location=Rome |first=Andy |last=Barff |publisher=Eurocontrol |access-date=2011-06-14 |archive-date=2016-03-03 |archive-url=https://web.archive.org/web/20160303210311/http://www.asas-tn.org/workshops/2nd-asas-tn2-workshop/session-3-b/1_MFFresults.ppt |url-status=deviated }} N.B: Direct download!

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{{Cite web |url=http://www.skybrary.aero/index.php/Airborne_Separation_Assurance_Systems_%28ASAS%29 |title=Airborne Separation Assurance Systems (ASAS) - SKYbrary Aviation Safety |access-date=2011-06-14 |archive-date=2021-11-04 |archive-url=https://web.archive.org/web/20211104014011/https://www.skybrary.aero/index.php/Airborne_Separation_Assurance_Systems_(ASAS) |url-status=live }} (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.,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, 2007M. 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 2008M. 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, 2009M.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 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{{Cite web |url=http://www.asstar.org/ |title=ASSTAR Home Page |access-date=2011-06-14 |archive-date=2011-06-24 |archive-url=https://web.archive.org/web/20110624142427/http://www.asstar.org/ |url-status=dead }} (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){{cite web |url=http://www.eurocontrol.int/content/sesar-and-research |title=SESAR and Research | EUROCONTROL |accessdate=2011-06-14 |url-status=dead |archiveurl=https://web.archive.org/web/20110612142054/http://www.eurocontrol.int/content/sesar-and-research |archivedate=2011-06-12 }}{{Cite web |url=http://www.sesarju.eu/programme/workpackages/wp-4-en-route-operations--191#tab_191_3 |title=SESAR WP4 Projects |access-date=2012-05-11 |archive-url=https://web.archive.org/web/20120506065157/http://www.sesarju.eu/programme/workpackages/wp-4-en-route-operations--191#tab_191_3#tab_191_3 |archive-date=2012-05-06 |url-status=dead }} and the U.S. Next Generation Air Transportation System{{Cite web |url=https://www.faa.gov/nextgen/ |title=Next Generation Air Transportation System (NextGen) |publisher=FAA |url-status=live |archive-url=https://web.archive.org/web/20220811064756/https://www.faa.gov/nextgen |archive-date=2022-08-11 }} (NextGen), even if limited to certain conditions and airspaces.

More recently, the iFly project{{Cite web |url=http://ifly.nlr.nl/ |title=IFly Web-site |access-date=2011-06-10 |archive-date=2022-08-06 |archive-url=https://web.archive.org/web/20220806064719/https://ifly.nlr.nl/ |url-status=live }} 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.{{Cite web |url=http://sesarinnovationdays.eu/files/SIDs/SID%202011-16.pdf |title=H.A.P. Blom, G.J. Bakker, Safety of advanced airborne self-separation under very high en-route traffic demand, SESAR Innovation Days, 2011. |access-date=2012-05-11 |archive-url=https://web.archive.org/web/20160304025539/http://sesarinnovationdays.eu/files/SIDs/SID%202011-16.pdf |archive-date=2016-03-04 |url-status=dead }} 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.

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

• How to safely transition from controlled airspace to self-separation airspace?
• What is the right balance between trajectory predictability and flexibility in order to achieve practical efficiency and acceptable safety?

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.

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Category:Aircraft operations

Category:Air traffic control