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class="vector-toc-numb">2</span> <span>Other collision avoidance systems</span> </div> </a> <button aria-controls="toc-Other_collision_avoidance_systems-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Other collision avoidance systems subsection</span> </button> <ul id="toc-Other_collision_avoidance_systems-sublist" class="vector-toc-list"> <li id="toc-Aircraft_collision_avoidance" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Aircraft_collision_avoidance"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.1</span> <span>Aircraft collision avoidance</span> </div> </a> <ul id="toc-Aircraft_collision_avoidance-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Terrain_collision_avoidance" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Terrain_collision_avoidance"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.2</span> <span>Terrain collision avoidance</span> </div> </a> <ul id="toc-Terrain_collision_avoidance-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-See_also" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#See_also"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>See also</span> </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>References</span> </div> </a> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-External_links" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" 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<div id="mw-content-text" class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none">Avionics system to avoid aircraft collision</div> <style data-mw-deduplicate="TemplateStyles:r1251242444">.mw-parser-output .ambox{border:1px solid #a2a9b1;border-left:10px solid #36c;background-color:#fbfbfb;box-sizing:border-box}.mw-parser-output .ambox+link+.ambox,.mw-parser-output .ambox+link+style+.ambox,.mw-parser-output .ambox+link+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+style+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+link+.ambox{margin-top:-1px}html body.mediawiki .mw-parser-output .ambox.mbox-small-left{margin:4px 1em 4px 0;overflow:hidden;width:238px;border-collapse:collapse;font-size:88%;line-height:1.25em}.mw-parser-output .ambox-speedy{border-left:10px solid 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role="presentation"><tbody><tr><td class="mbox-image"><div class="mbox-image-div"><span typeof="mw:File"><a href="/wiki/File:Question_book-new.svg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/50px-Question_book-new.svg.png" decoding="async" width="50" height="39" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/75px-Question_book-new.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/100px-Question_book-new.svg.png 2x" data-file-width="512" data-file-height="399" /></a></span></div></td><td class="mbox-text"><div class="mbox-text-span">This article <b>needs additional citations for <a href="/wiki/Wikipedia:Verifiability" title="Wikipedia:Verifiability">verification</a></b>.<span class="hide-when-compact"> Please help <a href="/wiki/Special:EditPage/Airborne_collision_avoidance_system" title="Special:EditPage/Airborne collision 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Unsourced material may be challenged and removed.<br /><small><span class="plainlinks"><i>Find sources:</i> <a rel="nofollow" class="external text" href="https://www.google.com/search?as_eq=wikipedia&q=%22Airborne+collision+avoidance+system%22">"Airborne collision avoidance system"</a> – <a rel="nofollow" class="external text" href="https://www.google.com/search?tbm=nws&q=%22Airborne+collision+avoidance+system%22+-wikipedia&tbs=ar:1">news</a> <b>·</b> <a rel="nofollow" class="external text" href="https://www.google.com/search?&q=%22Airborne+collision+avoidance+system%22&tbs=bkt:s&tbm=bks">newspapers</a> <b>·</b> <a rel="nofollow" class="external text" href="https://www.google.com/search?tbs=bks:1&q=%22Airborne+collision+avoidance+system%22+-wikipedia">books</a> <b>·</b> <a rel="nofollow" class="external text" href="https://scholar.google.com/scholar?q=%22Airborne+collision+avoidance+system%22">scholar</a> <b>·</b> <a rel="nofollow" class="external text" href="https://www.jstor.org/action/doBasicSearch?Query=%22Airborne+collision+avoidance+system%22&acc=on&wc=on">JSTOR</a></span></small></span> <span class="date-container"><i>(<span class="date">January 2008</span>)</i></span><span class="hide-when-compact"><i> (<small><a href="/wiki/Help:Maintenance_template_removal" title="Help:Maintenance template removal">Learn how and when to remove this message</a></small>)</i></span></div></td></tr></tbody></table> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:F-16D_ACAT_Aircraft.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/7/71/F-16D_ACAT_Aircraft.jpg/250px-F-16D_ACAT_Aircraft.jpg" decoding="async" width="250" height="196" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/71/F-16D_ACAT_Aircraft.jpg/375px-F-16D_ACAT_Aircraft.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/7/71/F-16D_ACAT_Aircraft.jpg/500px-F-16D_ACAT_Aircraft.jpg 2x" data-file-width="3000" data-file-height="2351" /></a><figcaption>The <a href="/wiki/U.S._Air_Force" class="mw-redirect" title="U.S. Air Force">U.S. Air Force</a>'s <a href="/wiki/F-16" class="mw-redirect" title="F-16">F-16</a>D Ground Collision Avoidance Technology (GCAT) aircraft</figcaption></figure> <p>An <b>airborne collision avoidance system</b> (<b>ACAS</b>, usually pronounced as <i>ay-kas</i>) operates independently of ground-based equipment and <a href="/wiki/Air_traffic_control" title="Air traffic control">air traffic control</a> 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 <a href="/wiki/Convention_on_International_Civil_Aviation" title="Convention on International Civil Aviation">Convention on International Civil Aviation</a>.<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> Much of the technology being applied to both military and general aviation today has been undergoing development by <a href="/wiki/NASA" title="NASA">NASA</a> and other partners since the 1980s.<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> </p><p>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 <i>en route</i> separation between aircraft (5 nautical miles (9.3 km) horizontal and 1,000 feet (300 m) vertical).<sup id="cite_ref-Free_flight_with_airborne_separation_assurance_3-0" class="reference"><a href="#cite_note-Free_flight_with_airborne_separation_assurance-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="TCAS">TCAS</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Airborne_collision_avoidance_system&action=edit&section=1" title="Edit section: TCAS"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1236090951">.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}</style><div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/Traffic_collision_avoidance_system#Versions" title="Traffic collision avoidance system">Traffic collision avoidance system § Versions</a></div> <p>As of 2022, the only implementations that meets the ACAS II standards set by <a href="/wiki/ICAO" class="mw-redirect" title="ICAO">ICAO</a> are Versions 7.0 and 7.1 of TCAS II (<a href="/wiki/Traffic_Collision_Avoidance_System" class="mw-redirect" title="Traffic Collision Avoidance System">Traffic Collision Avoidance System</a>) produced by <a href="/wiki/Garmin" title="Garmin">Garmin</a>, <a href="/wiki/Rockwell_Collins" title="Rockwell Collins">Rockwell Collins</a>, <a href="/wiki/Honeywell" title="Honeywell">Honeywell</a> and ACSS (Aviation Communication & Surveillance Systems; an <a href="/wiki/L-3_Communications" class="mw-redirect" title="L-3 Communications">L-3 Communications</a> and <a href="/wiki/Thales_Group" title="Thales Group">Thales Avionics</a> company).<sup id="cite_ref-ecguide2203_4-0" class="reference"><a href="#cite_note-ecguide2203-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: 14, 16">: 14, 16 </span></sup> </p><p>As of 1973, the United States <a href="/wiki/Federal_Aviation_Administration" title="Federal Aviation Administration">Federal Aviation Administration</a> (FAA) standard for transponder minimal operational performance, Technical Standard Order (TSO) C74c, contained errors which caused compatibility problems with <a href="/wiki/Air_traffic_control_radar_beacon_system" title="Air traffic control radar beacon system">air traffic control radar beacon system</a> (ATCRBS) radar and Traffic Collision Avoidance System (TCAS) abilities to detect aircraft transponders. First called "The Terra Problem", there have since been individual FAA <a href="/wiki/Airworthiness_Directive" class="mw-redirect" title="Airworthiness Directive">Airworthiness Directives</a> 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<sup class="noprint Inline-Template" style="margin-left:0.1em; white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Please_clarify" title="Wikipedia:Please clarify"><span title="The text near this tag may need clarification or removal of jargon. (January 2021)">clarification needed</span></a></i>]</sup> is in the <a href="/wiki/Technical_Standard_Order" title="Technical Standard Order">TSO</a>, 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.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (January 2021)">citation needed</span></a></i>]</sup> In 2009, a new version, TSO C74d<sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> was defined with tighter technical requirements.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (January 2021)">citation needed</span></a></i>]</sup> </p><p><a href="/w/index.php?title=AIS-P_(ACAS)&action=edit&redlink=1" class="new" title="AIS-P (ACAS) (page does not exist)">AIS-P (ACAS)</a><sup class="noprint Inline-Template" style="margin-left:0.1em; white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Please_clarify" title="Wikipedia:Please clarify"><span title="The text near this tag may need clarification or removal of jargon. (January 2021)">clarification needed</span></a></i>]</sup> 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.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (January 2021)">citation needed</span></a></i>]</sup> It awaits member country submission to the ICAO as a requested approval.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (January 2021)">citation needed</span></a></i>]</sup> </p> <div class="mw-heading mw-heading2"><h2 id="Other_collision_avoidance_systems">Other collision avoidance systems</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Airborne_collision_avoidance_system&action=edit&section=2" title="Edit section: Other collision avoidance systems"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Modern aircraft can use several types of <b>collision avoidance systems</b> to prevent unintentional contact with other aircraft, obstacles, or the ground. </p> <div class="mw-heading mw-heading3"><h3 id="Aircraft_collision_avoidance">Aircraft collision avoidance</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Airborne_collision_avoidance_system&action=edit&section=3" title="Edit section: Aircraft collision avoidance"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Some of the systems are designed to avoid collisions with other aircraft and <a href="/wiki/UAV" class="mw-redirect" title="UAV">UAVs</a>. They are referred to as "electronic conspicuity" by the <a href="/wiki/UK_CAA" class="mw-redirect" title="UK CAA">UK CAA</a>.<sup id="cite_ref-caaECDevices_6-0" class="reference"><a href="#cite_note-caaECDevices-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> </p> <ul><li>Airborne <a href="/wiki/Radar" title="Radar">radar</a> can detect the relative location of other aircraft, and has been in military use since <a href="/wiki/World_War_II" title="World War II">World War II</a>, when it was introduced to help night fighters (such as the <a href="/wiki/De_Havilland_Mosquito" title="De Havilland Mosquito">de Havilland Mosquito</a> and <a href="/wiki/Messerschmitt_Bf_110" title="Messerschmitt Bf 110">Messerschmitt Bf 110</a>) locate bombers. While larger civil aircraft carry <a href="/wiki/Weather_radar" title="Weather radar">weather radar</a>, sensitive anti-collision radar is rare in non-military aircraft.</li> <li><a href="/wiki/Traffic_collision_avoidance_system" title="Traffic collision avoidance system">Traffic collision avoidance system</a> (TCAS), the implementation of ACAS,<sup id="cite_ref-ecguide2203_4-1" class="reference"><a href="#cite_note-ecguide2203-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: 14">: 14 </span></sup> actively interrogates the <a href="/wiki/Transponder" title="Transponder">transponders</a> 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.</li> <li><figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:PCAS_Xrx.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/5/5e/PCAS_Xrx.jpg/220px-PCAS_Xrx.jpg" decoding="async" width="220" height="153" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/5/5e/PCAS_Xrx.jpg/330px-PCAS_Xrx.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/5/5e/PCAS_Xrx.jpg/440px-PCAS_Xrx.jpg 2x" data-file-width="2760" data-file-height="1917" /></a><figcaption>Small PCAS device for use in light aircraft.</figcaption></figure>a <a href="/wiki/Portable_Collision_Avoidance_System" class="mw-redirect" title="Portable Collision Avoidance System">Portable Collision Avoidance System</a> (PCAS) is a less expensive, passive version of TCAS designed for <a href="/wiki/General_aviation" title="General aviation">general aviation</a> 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.</li> <li><a href="/wiki/FLARM" title="FLARM">FLARM</a> 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 <a href="/wiki/Wide_Area_Augmentation_System" title="Wide Area Augmentation System">WAAS</a> 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.</li></ul> <div class="mw-heading mw-heading3"><h3 id="Terrain_collision_avoidance">Terrain collision avoidance</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Airborne_collision_avoidance_system&action=edit&section=4" title="Edit section: Terrain collision avoidance"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li>a <a href="/wiki/Ground_proximity_warning_system" title="Ground proximity warning system">Ground proximity warning system</a> (GPWS), or <i>Ground collision warning system</i> (GCWS), which uses a <a href="/wiki/Radar_altimeter" title="Radar altimeter">radar altimeter</a> to detect proximity to the ground or unusual descent rates. GPWS is common on civil airliners and larger <a href="/wiki/General_aviation" title="General aviation">general aviation</a> aircraft.</li> <li>a <a href="/wiki/Terrain_awareness_and_warning_system" title="Terrain awareness and warning system">Terrain awareness and warning system</a> (TAWS) uses a digital terrain map, together with position information from a navigation system such as <a href="/wiki/GPS" class="mw-redirect" title="GPS">GPS</a>, 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 (<a href="/wiki/Automatic_Ground_Collision_Avoidance_System" title="Automatic Ground Collision Avoidance System">Automatic Ground Collision Avoidance System</a>) and PARS (Pilot Activated Recovery System) that was installed on the entire USAF fleet of F-16's in 2014.<sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup></li> <li><a href="/wiki/Synthetic_vision" class="mw-redirect" title="Synthetic vision">Synthetic vision</a> 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.</li></ul> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Airborne_collision_avoidance_system&action=edit&section=5" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Acronyms_and_abbreviations_in_avionics" class="mw-redirect" title="Acronyms and abbreviations in avionics">Acronyms and abbreviations in avionics</a></li> <li><a href="/wiki/Air_traffic_control" title="Air traffic control">Air traffic control</a></li> <li><a href="/wiki/Automatic_dependent_surveillance_%E2%80%93_broadcast" class="mw-redirect" title="Automatic dependent surveillance – broadcast">Automatic dependent surveillance – broadcast</a></li> <li><a href="/wiki/Avionics" title="Avionics">Avionics</a></li> <li><a href="/wiki/Collision_avoidance" class="mw-redirect" title="Collision avoidance">Collision avoidance</a></li></ul> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Airborne_collision_avoidance_system&action=edit&section=6" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist reflist-columns references-column-width" style="column-width: 30em;"> <ol class="references"> <li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20100421004027/http://www.eurocontrol.int/msa/public/standard_page/ACAS_ICAO_Provisions.html">"EUROCONTROL - 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Archived from <a rel="nofollow" class="external text" href="http://www.eurocontrol.int/msa/public/standard_page/ACAS_ICAO_Provisions.html">the original</a> on 2010-04-21<span class="reference-accessdate">. Retrieved <span class="nowrap">2010-04-18</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=EUROCONTROL+-+ACAS+II+ICAO+Provisions&rft_id=http%3A%2F%2Fwww.eurocontrol.int%2Fmsa%2Fpublic%2Fstandard_page%2FACAS_ICAO_Provisions.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAirborne+collision+avoidance+system" class="Z3988"></span></span> </li> <li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.nasa.gov/centers/armstrong/Features/Auto-GCAS_Installed_in_USAF_F-16s.html">"NASA-Pioneered Automatic Ground-Collision Avoidance System Operational"</a>. <i>NASA website</i><span class="reference-accessdate">. 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National Aerospace Laboratory NLR.]</span> </li> <li id="cite_note-ecguide2203-4"><span class="mw-cite-backlink">^ <a href="#cite_ref-ecguide2203_4-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-ecguide2203_4-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation book cs1"><a rel="nofollow" class="external text" href="https://www.eurocontrol.int/sites/default/files/2022-03/eurocontrol-safety-acas-guide-4-1.pdf"><i>Airborne Collision Avoidance System (ACAS) guide</i></a> <span class="cs1-format">(PDF)</span>. <a href="/wiki/Eurocontrol" title="Eurocontrol">Eurocontrol</a>. 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Federal Aviation Administration.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=TSO+C74d+Air+Traffic+Control+Radar+Beacon+System+%28ATCRBS%29+Airborne+Equipment&rft.pub=Federal+Aviation+Administration&rft_id=http%3A%2F%2Frgl.faa.gov%2FRegulatory_and_Guidance_Library%2FrgTSO.nsf%2F0%2F15f9a125457291938625752300762aae%2F%24FILE%2FTSO-C74d.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAirborne+collision+avoidance+system" class="Z3988"></span></span> </li> <li id="cite_note-caaECDevices-6"><span class="mw-cite-backlink"><b><a href="#cite_ref-caaECDevices_6-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.caa.co.uk/General-aviation/Aircraft-ownership-and-maintenance/Electronic-Conspicuity-devices/">"Electronic conspicuity devices"</a>. <i>UK CAA</i><span class="reference-accessdate">. Retrieved <span class="nowrap">13 September</span> 2022</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=UK+CAA&rft.atitle=Electronic+conspicuity+devices&rft_id=https%3A%2F%2Fwww.caa.co.uk%2FGeneral-aviation%2FAircraft-ownership-and-maintenance%2FElectronic-Conspicuity-devices%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAirborne+collision+avoidance+system" class="Z3988"></span></span> </li> <li id="cite_note-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-7">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFJedick2014" class="citation web cs1">Jedick, Rocky (14 December 2014). <a rel="nofollow" class="external text" href="http://goflightmedicine.com/gcat/">"Ground Collision Avoidance System"</a>. <i>Go Flight Medicine</i><span class="reference-accessdate">. Retrieved <span class="nowrap">16 Dec</span> 2014</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Go+Flight+Medicine&rft.atitle=Ground+Collision+Avoidance+System&rft.date=2014-12-14&rft.aulast=Jedick&rft.aufirst=Rocky&rft_id=http%3A%2F%2Fgoflightmedicine.com%2Fgcat%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3AAirborne+collision+avoidance+system" class="Z3988"></span></span> </li> </ol></div> <div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Airborne_collision_avoidance_system&action=edit&section=7" title="Edit section: External links"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a rel="nofollow" class="external text" href="https://www.skybrary.aero/index.php/ACAS">ACAS on Skybrary</a></li> <li><a rel="nofollow" class="external text" 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href="/wiki/Aircraft_systems" title="Aircraft systems">systems</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Airframe" title="Airframe">Airframe</a> structure</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Aft_pressure_bulkhead" title="Aft pressure bulkhead">Aft pressure bulkhead</a></li> <li><a href="/wiki/Cabane_strut" class="mw-redirect" title="Cabane strut">Cabane strut</a></li> <li><a href="/wiki/Aircraft_canopy" title="Aircraft canopy">Canopy</a></li> <li><a href="/wiki/Crack_arrestor" title="Crack arrestor">Crack arrestor</a></li> <li><a href="/wiki/Cruciform_tail" title="Cruciform tail">Cruciform tail</a></li> <li><a href="/wiki/Aircraft_dope" title="Aircraft dope">Dope</a></li> <li><a href="/wiki/Empennage" title="Empennage">Empennage</a></li> <li><a href="/wiki/Aircraft_fabric_covering" title="Aircraft fabric covering">Fabric covering</a></li> <li><a href="/wiki/Aircraft_fairing" title="Aircraft fairing">Fairing</a></li> <li><a href="/wiki/Flying_wires" class="mw-redirect" title="Flying wires">Flying wires</a></li> <li><a href="/wiki/Former" title="Former">Former</a></li> <li><a href="/wiki/Fuselage" title="Fuselage">Fuselage</a></li> <li><a href="/wiki/Hardpoint" title="Hardpoint">Hardpoint</a></li> <li><a href="/wiki/Interplane_strut" class="mw-redirect" title="Interplane strut">Interplane strut</a></li> <li><a href="/wiki/Jury_strut" class="mw-redirect" title="Jury strut">Jury strut</a></li> <li><a href="/wiki/Leading_edge" title="Leading edge">Leading edge</a></li> <li><a href="/wiki/Lift_strut" class="mw-redirect" title="Lift strut">Lift strut</a></li> <li><a href="/wiki/Longeron" title="Longeron">Longeron</a></li> <li><a href="/wiki/Nacelle" title="Nacelle">Nacelle</a></li> <li><a href="/wiki/Rib_(aeronautics)" title="Rib (aeronautics)">Rib</a></li> <li><a href="/wiki/Spar_(aeronautics)" title="Spar (aeronautics)">Spar</a></li> <li><a href="/wiki/Stabilizer_(aeronautics)" title="Stabilizer (aeronautics)">Stabilizer</a></li> <li><a href="/wiki/Stressed_skin" title="Stressed skin">Stressed skin</a></li> <li><a href="/wiki/Strut" title="Strut">Strut</a></li> <li><a href="/wiki/T-tail" title="T-tail">T-tail</a></li> <li><a href="/wiki/Tailplane" title="Tailplane">Tailplane</a></li> <li><a href="/wiki/Trailing_edge" title="Trailing edge">Trailing edge</a></li> <li><a href="/wiki/Twin_tail#Variations" title="Twin tail">Triple tail</a></li> <li><a href="/wiki/Twin_tail" title="Twin tail">Twin tail</a></li> <li><a href="/wiki/V-tail" title="V-tail">V-tail</a></li> <li><a href="/wiki/Vertical_stabilizer" title="Vertical stabilizer">Vertical stabilizer</a></li> <li><a href="/wiki/Wing_root" title="Wing root">Wing root</a></li> <li><a href="/wiki/Wing_tip" title="Wing tip">Wing tip</a></li> <li><a href="/wiki/Wingbox" title="Wingbox">Wingbox</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Aircraft_flight_control_system" title="Aircraft flight control system">Flight controls</a></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Aileron" title="Aileron">Aileron</a></li> <li><a href="/wiki/Air_brake_(aeronautics)" title="Air brake (aeronautics)">Airbrake</a></li> <li><a href="/wiki/Aircraft_flight_control_system#Artificial_feel_devices" title="Aircraft flight control system">Artificial feel</a></li> <li><a href="/wiki/Autopilot" title="Autopilot">Autopilot</a></li> <li><a href="/wiki/Canard_(aeronautics)" title="Canard (aeronautics)">Canard</a></li> <li><a href="/wiki/Centre_stick" title="Centre stick">Centre stick</a></li> <li><a href="/wiki/Deceleron" title="Deceleron">Deceleron</a></li> <li><a href="/wiki/Dive_brake" title="Dive brake">Dive brake</a></li> <li><a href="/wiki/Dual_control_(aviation)" title="Dual control (aviation)">Dual control</a></li> <li><a href="/wiki/Electro-hydraulic_actuator" title="Electro-hydraulic actuator">Electro-hydraulic actuator</a></li> <li><a href="/wiki/Elevator_(aeronautics)" title="Elevator (aeronautics)">Elevator</a></li> <li><a href="/wiki/Elevon" title="Elevon">Elevon</a></li> <li><a href="/wiki/Flaperon" title="Flaperon">Flaperon</a></li> <li><a href="/wiki/Flight_control_modes" title="Flight control modes">Flight control modes</a></li> <li><a href="/wiki/Fly-by-wire" title="Fly-by-wire">Fly-by-wire</a></li> <li><a href="/wiki/Gust_lock" title="Gust lock">Gust lock</a></li> <li><a href="/wiki/HOTAS" title="HOTAS">HOTAS</a></li> <li><a href="/wiki/Rudder#Aircraft_rudders" title="Rudder">Rudder</a></li> <li><a href="/wiki/Rudder_pedal" title="Rudder pedal">Rudder pedals</a></li> <li><a href="/wiki/Servo_tab" title="Servo tab">Servo tab</a></li> <li><a href="/wiki/Side-stick" title="Side-stick">Side-stick</a></li> <li><a href="/wiki/Spoiler_(aeronautics)" title="Spoiler (aeronautics)">Spoiler</a></li> <li><a href="/wiki/Spoileron" title="Spoileron">Spoileron</a></li> <li><a href="/wiki/Stabilator" title="Stabilator">Stabilator</a></li> <li><a href="/wiki/Stick_pusher" title="Stick pusher">Stick pusher</a></li> <li><a href="/wiki/Stick_shaker" title="Stick shaker">Stick shaker</a></li> <li><a href="/wiki/Trim_tab" title="Trim tab">Trim tab</a></li> <li><a href="/wiki/Wing_warping" title="Wing warping">Wing warping</a></li> <li><a href="/wiki/Yaw_damper" title="Yaw damper">Yaw damper</a></li> <li><a href="/wiki/Yoke_(aeronautics)" title="Yoke (aeronautics)">Yoke</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Aerodynamics" title="Aerodynamics">Aerodynamic</a> and <a href="/wiki/High-lift_device" title="High-lift device">high-lift</a><br />devices</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Boeing_X-53_Active_Aeroelastic_Wing" title="Boeing X-53 Active Aeroelastic Wing">Active Aeroelastic Wing</a></li> <li><a href="/wiki/Adaptive_compliant_wing" title="Adaptive compliant wing">Adaptive compliant wing</a></li> <li><a href="/wiki/Anti-shock_body" title="Anti-shock body">Anti-shock body</a></li> <li><a href="/wiki/Blown_flap" title="Blown flap">Blown flap</a></li> <li><a href="/wiki/Channel_wing" title="Channel wing">Channel wing</a></li> <li><a href="/wiki/Leading-edge_extension#Dogtooth_extension" title="Leading-edge extension">Dog-tooth</a></li> <li><a href="/wiki/Drag-reducing_aerospike" title="Drag-reducing aerospike">Drag-reducing aerospike</a></li> <li><a href="/wiki/Flap_(aeronautics)" title="Flap (aeronautics)">Flap</a></li> <li><a href="/wiki/Gouge_flap" title="Gouge flap">Gouge flap</a></li> <li><a href="/wiki/Gurney_flap" title="Gurney flap">Gurney flap</a></li> <li><a href="/wiki/Krueger_flap" title="Krueger flap">Krueger flap</a></li> <li><a href="/wiki/Leading-edge_cuff" title="Leading-edge cuff">Leading-edge cuff</a></li> <li><a href="/wiki/Leading-edge_droop_flap" title="Leading-edge droop flap">Leading-edge droop flap</a></li> <li><a href="/wiki/Leading-edge_extension" title="Leading-edge extension">LEX</a></li> <li><a href="/wiki/Leading-edge_slat" title="Leading-edge slat">Slats</a></li> <li><a href="/wiki/Leading-edge_slot" title="Leading-edge slot">Slot</a></li> <li><a href="/wiki/Stall_strips" title="Stall strips">Stall strips</a></li> <li><a href="/wiki/Strake_(aeronautics)" title="Strake (aeronautics)">Strake</a></li> <li><a href="/wiki/Variable-sweep_wing" title="Variable-sweep wing">Variable-sweep wing</a></li> <li><a href="/wiki/Vortex_generator" title="Vortex generator">Vortex generator</a></li> <li><a href="/wiki/Vortilon" title="Vortilon">Vortilon</a></li> <li><a href="/wiki/Wing_fence" title="Wing fence">Wing fence</a></li> <li><a href="/wiki/Wingtip_device" title="Wingtip device">Winglet</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Avionics" title="Avionics">Avionic</a> and <a href="/wiki/Flight_instruments" title="Flight instruments">flight<br />instrument</a> systems</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a class="mw-selflink selflink">ACAS</a></li> <li><a href="/wiki/Air_data_boom" title="Air data boom">Air data boom</a></li> <li><a href="/wiki/Air_data_computer" title="Air data computer">Air data computer</a></li> <li><a href="/wiki/Aircraft_periscope" class="mw-redirect" title="Aircraft periscope">Aircraft periscope</a></li> <li><a href="/wiki/Airspeed_indicator" title="Airspeed indicator">Airspeed indicator</a></li> <li><a href="/wiki/Altimeter" title="Altimeter">Altimeter</a></li> <li><a href="/wiki/Annunciator_panel" title="Annunciator panel">Annunciator panel</a></li> <li><a href="/wiki/Astrodome_(aeronautics)" title="Astrodome (aeronautics)">Astrodome</a></li> <li><a href="/wiki/Attitude_indicator" title="Attitude indicator">Attitude indicator</a></li> <li><a href="/wiki/Compass" title="Compass">Compass</a></li> <li><a href="/wiki/Course_deviation_indicator" title="Course deviation indicator">Course deviation indicator</a></li> <li><a href="/wiki/Electronic_flight_instrument_system" title="Electronic flight instrument system">EFIS</a></li> <li><a href="/wiki/Engine-indicating_and_crew-alerting_system" title="Engine-indicating and crew-alerting system">EICAS</a></li> <li><a href="/wiki/Flight_management_system" title="Flight management system">Flight management system</a></li> <li><a href="/wiki/Glass_cockpit" title="Glass cockpit">Glass cockpit</a></li> <li><a href="/wiki/Global_Positioning_System" title="Global Positioning System">GPS</a></li> <li><a href="/wiki/Head-up_display" title="Head-up display">Head-up display</a></li> <li><a href="/wiki/Heading_indicator" title="Heading indicator">Heading indicator</a></li> <li><a href="/wiki/Horizontal_situation_indicator" title="Horizontal situation indicator">Horizontal situation indicator</a></li> <li><a href="/wiki/Inertial_navigation_system" title="Inertial navigation system">INS</a></li> <li><a href="/wiki/Integrated_standby_instrument_system" title="Integrated standby instrument system">ISIS</a></li> <li><a href="/wiki/Multi-function_display" title="Multi-function display">Multi-function display</a></li> <li><a href="/wiki/Pitot%E2%80%93static_system" title="Pitot–static system">Pitot–static system</a></li> <li><a href="/wiki/Radar_altimeter" title="Radar altimeter">Radar altimeter</a></li> <li><a href="/wiki/Traffic_collision_avoidance_system" title="Traffic collision avoidance system">TCAS</a></li> <li><a href="/wiki/Transponder_(aeronautics)" title="Transponder (aeronautics)">Transponder</a></li> <li><a href="/wiki/Turn_and_slip_indicator" title="Turn and slip indicator">Turn and slip indicator</a></li> 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