Editing Air traffic control (section)

===Radar coverage===
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[[File:Grandballonsud.jpg|thumb|Unmanned radar on a remote mountain]]

Some air navigation service providers (e.g., Airservices Australia, the U.S. Federal Aviation Administration, [[Nav Canada]], etc.) have implemented [[automatic dependent surveillance – broadcast]] (ADS-B) as part of their surveillance capability.  This newer technology reverses the radar concept.  Instead of radar 'finding' a target by interrogating the transponder, the ADS-B equipped aircraft 'broadcasts' a position report as determined by the [[navigation]] equipment on board the aircraft.  ADS-C is another mode of automatic dependent surveillance, however ADS-C operates in the 'contract' mode, where the aircraft reports a position, automatically or initiated by the pilot, based on a predetermined time interval.  It is also possible for controllers to request more frequent reports to more quickly establish aircraft position for specific reasons.  However, since the cost for each report is charged by the ADS service providers to the company operating the aircraft,{{Disputed inline|ADS-B|date=March 2014}} more frequent reports are not commonly requested, except in emergency situations.  ADS-C is significant, because it can be used where it is not possible to locate the infrastructure for a radar system (e.g., over water).  Computerised radar displays are now being designed to accept ADS-C inputs as part of their display.<ref>{{Cite web |title=Automatic Dependent Surveillance - Contract (ADS-C) |url=https://www.skybrary.aero/index.php/Automatic_Dependent_Surveillance_-_Contract_(ADS-C) |website=SKYbrary.aero |publisher=SKYbrary Aviation Safety |access-date=23 February 2021 }}</ref>{{Verification needed|date=March 2025}}

A radar archive system (RAS) keeps an electronic record of all radar information, preserving it for a few weeks.  This information can be useful for [[search and rescue]].  When an aircraft has 'disappeared' from radar screens, a controller can review the last radar returns from the aircraft to determine its likely position.  For an example, see the crash report in the following citation.<ref>{{Cite web |title=crash report |url=http://www.tsb.gc.ca/eng/rapports-reports/aviation/1996/a96a0207/a96a0207.asp |website=TSB.gc.ca |publisher= |date=1996 |access-date=24 August 2010 |archive-url=https://web.archive.org/web/20120307102104/http://www.tsb.gc.ca/eng/rapports-reports/aviation/1996/a96a0207/a96a0207.asp |archive-date=7 March 2012 |url-status=dead}}</ref>