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codes subsection</span> </button> <ul id="toc-Transponder_codes-sublist" class="vector-toc-list"> <li id="toc-Codes_assigned_by_air_traffic_control" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Codes_assigned_by_air_traffic_control"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.1</span> <span>Codes assigned by air traffic control</span> </div> </a> <ul id="toc-Codes_assigned_by_air_traffic_control-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Emergency_codes" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Emergency_codes"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.2</span> <span>Emergency codes</span> </div> </a> <ul id="toc-Emergency_codes-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Transponder-related_incidents" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" 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class="vector-unpinned-container"> </div> </div> </div> </nav> <h1 id="firstHeading" class="firstHeading mw-first-heading"><span class="mw-page-title-main">Transponder (aeronautics)</span></h1> <div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-lang-btn" class="vector-dropdown-checkbox mw-interlanguage-selector" aria-label="Go to an article in another language. Available in 17 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-17" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">17 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D9%85%D8%B3%D8%AA%D8%AC%D9%8A%D8%A8" title="مستجيب – Arabic" lang="ar" hreflang="ar" data-title="مستجيب" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/Transpond%C3%A9r" title="Transpondér – Czech" lang="cs" hreflang="cs" data-title="Transpondér" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-da mw-list-item"><a href="https://da.wikipedia.org/wiki/Transponder_(luftfart)" title="Transponder (luftfart) – Danish" lang="da" hreflang="da" data-title="Transponder (luftfart)" data-language-autonym="Dansk" data-language-local-name="Danish" class="interlanguage-link-target"><span>Dansk</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Transpondercode" title="Transpondercode – German" lang="de" hreflang="de" data-title="Transpondercode" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Transpondedor_(aeron%C3%A1utica)" title="Transpondedor (aeronáutica) – Spanish" lang="es" hreflang="es" data-title="Transpondedor (aeronáutica)" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D8%AA%D8%B1%D8%A7%D9%86%D8%B3%D9%BE%D9%88%D9%86%D8%AF%D8%B1_(%D9%87%D9%88%D8%A7%D9%86%D9%88%D8%B1%D8%AF%DB%8C)" title="ترانسپوندر (هوانوردی) – Persian" lang="fa" hreflang="fa" data-title="ترانسپوندر (هوانوردی)" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Transpondeur_(aviation)" title="Transpondeur (aviation) – French" lang="fr" hreflang="fr" data-title="Transpondeur (aviation)" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/%ED%8A%B8%EB%9E%9C%EC%8A%A4%ED%8F%B0%EB%8D%94_(%ED%95%AD%EA%B3%B5)" title="트랜스폰더 (항공) – Korean" lang="ko" hreflang="ko" data-title="트랜스폰더 (항공)" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Transponder_code" title="Transponder code – Italian" lang="it" hreflang="it" data-title="Transponder code" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-lmo mw-list-item"><a href="https://lmo.wikipedia.org/wiki/Transponder_(Reoplan)" title="Transponder (Reoplan) – Lombard" lang="lmo" hreflang="lmo" data-title="Transponder (Reoplan)" data-language-autonym="Lombard" data-language-local-name="Lombard" class="interlanguage-link-target"><span>Lombard</span></a></li><li class="interlanguage-link interwiki-hu mw-list-item"><a href="https://hu.wikipedia.org/wiki/Transzponder" title="Transzponder – Hungarian" lang="hu" hreflang="hu" data-title="Transzponder" data-language-autonym="Magyar" data-language-local-name="Hungarian" class="interlanguage-link-target"><span>Magyar</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/Kod_transpondera" title="Kod transpondera – Polish" lang="pl" hreflang="pl" data-title="Kod transpondera" data-language-autonym="Polski" data-language-local-name="Polish" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%A1%D0%B0%D0%BC%D0%BE%D0%BB%D1%91%D1%82%D0%BD%D1%8B%D0%B9_%D1%80%D0%B0%D0%B4%D0%B8%D0%BE%D0%BB%D0%BE%D0%BA%D0%B0%D1%86%D0%B8%D0%BE%D0%BD%D0%BD%D1%8B%D0%B9_%D0%BE%D1%82%D0%B2%D0%B5%D1%82%D1%87%D0%B8%D0%BA" title="Самолётный радиолокационный ответчик – Russian" lang="ru" hreflang="ru" data-title="Самолётный радиолокационный ответчик" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-fi mw-list-item"><a href="https://fi.wikipedia.org/wiki/Toisiotutkavastain" title="Toisiotutkavastain – Finnish" lang="fi" hreflang="fi" data-title="Toisiotutkavastain" data-language-autonym="Suomi" data-language-local-name="Finnish" class="interlanguage-link-target"><span>Suomi</span></a></li><li class="interlanguage-link interwiki-tr mw-list-item"><a href="https://tr.wikipedia.org/wiki/Transponder_(havac%C4%B1l%C4%B1k)" title="Transponder (havacılık) – Turkish" lang="tr" hreflang="tr" data-title="Transponder (havacılık)" data-language-autonym="Türkçe" data-language-local-name="Turkish" class="interlanguage-link-target"><span>Türkçe</span></a></li><li class="interlanguage-link interwiki-ur mw-list-item"><a href="https://ur.wikipedia.org/wiki/%D9%B9%D8%B1%D8%A7%D9%86%D8%B3%D9%BE%D9%88%D9%86%DA%88%D8%B1_(%DB%81%D9%88%D8%A7%D9%BE%DB%8C%D9%85%D8%A7%D8%A6%DB%8C)" title="ٹرانسپونڈر (ہواپیمائی) – Urdu" lang="ur" hreflang="ur" data-title="ٹرانسپونڈر (ہواپیمائی)" data-language-autonym="اردو" data-language-local-name="Urdu" class="interlanguage-link-target"><span>اردو</span></a></li><li class="interlanguage-link interwiki-zh mw-list-item"><a href="https://zh.wikipedia.org/wiki/%E5%BA%94%E7%AD%94%E6%9C%BA" title="应答机 – Chinese" lang="zh" hreflang="zh" data-title="应答机" data-language-autonym="中文" data-language-local-name="Chinese" class="interlanguage-link-target"><span>中文</span></a></li> </ul> <div class="after-portlet after-portlet-lang"><span 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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">Airborne radio transponder</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">"Squawk code" redirects here. For the similarly named compression scheme, see <a href="/wiki/SQUOZE" title="SQUOZE">SQUOZE</a>.</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">For uses non related to aeronautics, see <a href="/wiki/Transponder" title="Transponder">Transponder</a>.</div> <p class="mw-empty-elt"> </p> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:CessnaARC-RT-359ATransponder04.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/a/ae/CessnaARC-RT-359ATransponder04.jpg/250px-CessnaARC-RT-359ATransponder04.jpg" decoding="async" width="250" height="167" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/ae/CessnaARC-RT-359ATransponder04.jpg/375px-CessnaARC-RT-359ATransponder04.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/ae/CessnaARC-RT-359ATransponder04.jpg/500px-CessnaARC-RT-359ATransponder04.jpg 2x" data-file-width="750" data-file-height="502" /></a><figcaption>Cessna ARC RT-359A transponder (beige box), beneath a VHF radio. In this example, the transponder code selected is 1200 for <a href="/wiki/Visual_flight_rules" title="Visual flight rules">VFR</a> flight (in North American airspace). The green IDENT button is marked "ID".</figcaption></figure> <p>A <b>transponder</b> (short for <i>trans</i>mitter-res<i>ponder</i><sup id="cite_ref-Mangine_1-0" class="reference"><a href="#cite_note-Mangine-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> and sometimes abbreviated to XPDR,<sup id="cite_ref-FreeDict1_2-0" class="reference"><a href="#cite_note-FreeDict1-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> XPNDR,<sup id="cite_ref-FreeDict2_3-0" class="reference"><a href="#cite_note-FreeDict2-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> TPDR<sup id="cite_ref-FreeDict3_4-0" class="reference"><a href="#cite_note-FreeDict3-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> or TP<sup id="cite_ref-FreeDict4_5-0" class="reference"><a href="#cite_note-FreeDict4-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup>) is an electronic device that produces a response when it receives a radio-frequency interrogation. Aircraft have <a href="/wiki/Transponder" title="Transponder">transponders</a> to assist in identifying them on air traffic control <a href="/wiki/Radar" title="Radar">radar</a>. <a href="/wiki/Airborne_Collision_Avoidance_System" class="mw-redirect" title="Airborne Collision Avoidance System">Collision avoidance systems</a> have been developed to use transponder transmissions as a means of detecting aircraft at risk of colliding with each other.<sup id="cite_ref-TCAIM_6-0" class="reference"><a href="#cite_note-TCAIM-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Peppler_7-0" class="reference"><a href="#cite_note-Peppler-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> </p><p><a href="/wiki/Air_traffic_control" title="Air traffic control">Air traffic control</a> units use the term "squawk" when they are assigning an aircraft a transponder code, <i>e.g.</i>, "Squawk 7421". Squawk thus can be said to mean "select transponder code" or "squawking <i>xxxx</i>" to mean "I have selected transponder code <i>xxxx</i>".<sup id="cite_ref-TCAIM_6-1" class="reference"><a href="#cite_note-TCAIM-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> </p><p>The transponder receives interrogation from the Secondary Surveillance Radar on 1030 MHz and replies on 1090 MHz. </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Secondary_surveillance_radar">Secondary surveillance radar</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Transponder_(aeronautics)&action=edit&section=1" title="Edit section: Secondary surveillance radar"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Secondary_surveillance_radar" title="Secondary surveillance radar">Secondary surveillance radar</a></div> <p>Secondary surveillance radar (SSR) is referred to as "secondary", to distinguish it from the "primary radar" that works by passively reflecting a radio signal off the skin of the aircraft. Primary radar determines range and bearing to a target with reasonably high fidelity, but it cannot determine target elevation (altitude) reliably except at close range. SSR uses an active transponder (beacon) to transmit a response to an interrogation by a secondary radar. This response most often includes the aircraft's <a href="/wiki/Pressure_altitude" title="Pressure altitude">pressure altitude</a> and a 4-digit <a href="/wiki/Octal" title="Octal">octal</a> identifier.<sup id="cite_ref-Peppler_7-1" class="reference"><a href="#cite_note-Peppler-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Operation">Operation</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Transponder_(aeronautics)&action=edit&section=2" title="Edit section: Operation"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>A pilot may be requested to squawk a given code by an air traffic controller, via the radio, using a phrase such as "Cessna 123AB, squawk 0363". The pilot then selects the 0363 code on their transponder and the track on the air traffic controller's radar screen will become correctly associated with their identity.<sup id="cite_ref-TCAIM_6-2" class="reference"><a href="#cite_note-TCAIM-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Peppler_7-2" class="reference"><a href="#cite_note-Peppler-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> </p><p>Because primary radar generally gives bearing and range position information, but lacks altitude information, mode C and <a href="/wiki/Mode_S" class="mw-redirect" title="Mode S">mode S</a> transponders also report pressure altitude. Mode C altitude information conventionally comes from the pilot's altimeter, and is transmitted using a modified <a href="/wiki/Gray_code" title="Gray code">Gray code</a>, called a <a href="/wiki/Gillham_code" title="Gillham code">Gillham code</a>. Where the pilot's altimeter does not contain a suitable altitude encoder, a <i>blind encoder</i> (which does not directly display altitude) is connected to the transponder. Around busy <a href="/wiki/Airspace" title="Airspace">airspace</a> there is often a regulatory requirement that all aircraft be equipped with altitude-reporting mode C or mode S transponders. In the United States, this is known as a <a href="/wiki/Mode_C_veil" title="Mode C veil">Mode C veil</a>. Mode S transponders are compatible with transmitting the mode C signal, and have the capability to report in 25-foot increments; they receive information from a GPS receiver and also transmit location and speed. Without the pressure altitude reporting, the air traffic controller has no display of accurate altitude information, and must rely on the altitude reported by the pilot via radio.<sup id="cite_ref-TCAIM_6-3" class="reference"><a href="#cite_note-TCAIM-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Peppler_7-3" class="reference"><a href="#cite_note-Peppler-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> Similarly, the <a href="/wiki/Traffic_collision_avoidance_system" title="Traffic collision avoidance system">traffic collision avoidance system</a> (TCAS) installed on some aircraft needs the altitude information supplied by transponder signals. </p> <div class="mw-heading mw-heading2"><h2 id="IDENT">IDENT</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Transponder_(aeronautics)&action=edit&section=3" title="Edit section: IDENT"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>All mode A, C, and S transponders include an "IDENT" switch which activates a special thirteenth bit on the mode A reply known as IDENT, short for "identify". When ground-based radar equipment<sup id="cite_ref-AvNet2_9-0" class="reference"><a href="#cite_note-AvNet2-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> receives the IDENT bit, it results in the aircraft's blip "blossoming" on the radar scope. This is often used by the controller to locate the aircraft amongst others by requesting the ident function from the pilot, <i>e.g.</i>, "Cessna 123AB, squawk 0363 and ident".<sup id="cite_ref-TCAIM_6-4" class="reference"><a href="#cite_note-TCAIM-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Peppler_7-4" class="reference"><a href="#cite_note-Peppler-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> </p><p>Ident can also be used in case of a reported or suspected radio failure to determine if the failure is only one way and whether the pilot can still transmit <i>or</i> receive, but not both, <i>e.g.</i>, "Cessna 123AB, if you read, squawk ident".<sup id="cite_ref-Peppler_7-5" class="reference"><a href="#cite_note-Peppler-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Transponder_codes">Transponder codes</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Transponder_(aeronautics)&action=edit&section=4" title="Edit section: Transponder codes"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Transponder codes are four-digit numbers transmitted by an aircraft transponder in response to a secondary surveillance radar interrogation signal to assist air traffic controllers with traffic separation. A discrete transponder code (often called a squawk code) is assigned by air traffic controllers to identify an aircraft uniquely in a <a href="/wiki/Flight_information_region" title="Flight information region">flight information region</a> (FIR). This allows easy identification of aircraft on radar.<sup id="cite_ref-TCAIM_6-5" class="reference"><a href="#cite_note-TCAIM-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Peppler_7-6" class="reference"><a href="#cite_note-Peppler-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> </p><p>Codes are made of four <a href="/wiki/Octal" title="Octal">octal</a> digits; the dials on a transponder read from zero to seven, inclusive. Four octal digits can represent up to 4096 different codes, which is why such transponders are sometimes described as "4096 code transponders."<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> </p><p>The use of the word "squawk" comes from the system's origin in the World War II <a href="/wiki/Identification_friend_or_foe" title="Identification friend or foe">identification friend or foe</a> (IFF) system, which was code-named "Parrot".<sup id="cite_ref-11" class="reference"><a href="#cite_note-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-12" class="reference"><a href="#cite_note-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Codes_assigned_by_air_traffic_control">Codes assigned by air traffic control</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Transponder_(aeronautics)&action=edit&section=5" title="Edit section: Codes assigned by air traffic control"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Some codes can be selected by the pilot if and when the situation requires or allows it, without permission from air traffic control (ATC). Such codes are referred to as "conspicuity codes" in the UK.<sup id="cite_ref-ENR1.6.2_13-0" class="reference"><a href="#cite_note-ENR1.6.2-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> Other codes are generally assigned by ATC units.<sup id="cite_ref-TCAIM_6-6" class="reference"><a href="#cite_note-TCAIM-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Peppler_7-7" class="reference"><a href="#cite_note-Peppler-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> For flights on <a href="/wiki/Instrument_flight_rules" title="Instrument flight rules">instrument flight rules</a> (IFR), the squawk code is typically assigned as part of the departure clearance and stays the same throughout the flight.<sup id="cite_ref-TCAIM_6-7" class="reference"><a href="#cite_note-TCAIM-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Peppler_7-8" class="reference"><a href="#cite_note-Peppler-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> </p><p>Flights on <a href="/wiki/Visual_flight_rules" title="Visual flight rules">visual flight rules</a> (VFR), when in uncontrolled airspace, will "squawk VFR" (1200 in the US and Canada, 7000 in Europe). Upon contact with an ATC unit, they will be told to squawk a certain code. When changing frequency, for instance because the VFR flight leaves controlled airspace or changes to another ATC unit, the VFR flight will be told to "squawk VFR" again.<sup id="cite_ref-TCAIM_6-8" class="reference"><a href="#cite_note-TCAIM-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Peppler_7-9" class="reference"><a href="#cite_note-Peppler-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> </p><p>In order to avoid confusion over assigned squawk codes, ATC units will typically be allocated blocks of squawk codes, not overlapping with the blocks of nearby ATC units, to assign at their discretion. </p><p>Not all ATC units will use radar to identify aircraft, but they assign squawk codes nevertheless. As an example, London Information—the flight information service station that covers the lower half of the UK—does not have access to radar images, but does assign squawk code 1177 to all aircraft that receive a <a href="/wiki/Flight_information_service" title="Flight information service">flight information service</a> (FIS) from them. This tells other radar-equipped ATC units that a specific aircraft is listening on the London Information radio frequency, in case they need to contact that aircraft.<sup id="cite_ref-ENR1.6.2_13-1" class="reference"><a href="#cite_note-ENR1.6.2-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Emergency_codes">Emergency codes</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Transponder_(aeronautics)&action=edit&section=6" title="Edit section: Emergency codes"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The following codes are applicable worldwide. </p> <table class="wikitable sortable"> <tbody><tr> <th>Code</th> <th>Use </th></tr> <tr> <td>7500</td> <td><a href="/wiki/Aircraft_hijacking" title="Aircraft hijacking">Aircraft hijacking</a> (ICAO)<sup id="cite_ref-TCAIM_6-9" class="reference"><a href="#cite_note-TCAIM-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-JO711066D_14-0" class="reference"><a href="#cite_note-JO711066D-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> </td></tr> <tr> <td>7600</td> <td>Radio failure (<a href="/wiki/NORDO" title="NORDO">lost communications</a>) (ICAO)<sup id="cite_ref-TCAIM_6-10" class="reference"><a href="#cite_note-TCAIM-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-JO711066D_14-1" class="reference"><a href="#cite_note-JO711066D-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> </td></tr> <tr> <td>7700</td> <td>Emergency (ICAO)<sup id="cite_ref-TCAIM_6-11" class="reference"><a href="#cite_note-TCAIM-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-JO711066D_14-2" class="reference"><a href="#cite_note-JO711066D-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> </td></tr></tbody></table> <p>See <a href="/wiki/List_of_transponder_codes" title="List of transponder codes">List of transponder codes</a> for list of country-specific and historic allocations. </p> <div class="mw-heading mw-heading2"><h2 id="Transponder-related_incidents">Transponder-related incidents</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Transponder_(aeronautics)&action=edit&section=7" title="Edit section: Transponder-related incidents"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/1986_Cerritos_mid-air_collision" class="mw-redirect" title="1986 Cerritos mid-air collision">1986 Cerritos mid-air collision</a> — August 31, 1986 (one of the aircraft equipped with a Mode A, but not Mode C, transponder)</li> <li><a href="/wiki/Iran_Air_Flight_655" title="Iran Air Flight 655">Iran Air Flight 655</a> — July 3, 1988 (incorrect interpretation of transponder code, a factor in mistaken identity and shooting-down)</li> <li><a href="/wiki/Proteus_Airlines_Flight_706" title="Proteus Airlines Flight 706">Proteus Airlines Flight 706</a> — July 30, 1998 (mid-air collision; one of the aircraft had its transponder switched off)</li> <li><a href="/wiki/Korean_Air_Flight_85" class="mw-redirect" title="Korean Air Flight 85">Korean Air Flight 85</a> — September 11, 2001 (suspected hijack involving the transponder code, false alarm)</li> <li><a href="/wiki/Gol_Transportes_A%C3%A9reos_Flight_1907" title="Gol Transportes Aéreos Flight 1907">Gol Transportes Aéreos Flight 1907</a> — September 29, 2006 (midair collision; one of the aircraft had its transponder accidentally switched off)</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=Transponder_(aeronautics)&action=edit&section=8" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Aviation_transponder_interrogation_modes" title="Aviation transponder interrogation modes">Aviation transponder interrogation modes</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=Transponder_(aeronautics)&action=edit&section=9" 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"> <div class="mw-references-wrap mw-references-columns"><ol class="references"> <li id="cite_note-Mangine-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-Mangine_1-0">^</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 id="CITEREFMangine2007" class="citation web cs1">Mangine, Robert (2007). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20110816141015/http://forensicauto.net/id63.html">"The Truth About Transponders"</a>. 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Retrieved <span class="nowrap">September 11,</span> 2021</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=ENR+1.6.2+%E2%80%94+SSR+Operating+Procedures&rft.date=2021-07-29&rft_id=https%3A%2F%2Fwww.aurora.nats.co.uk%2FhtmlAIP%2FPublications%2F2021-09-09-AIRAC%2Fhtml%2FeAIP%2FEG-ENR-1.6-en-GB.html%23ENR-1.6.2&rfr_id=info%3Asid%2Fen.wikipedia.org%3ATransponder+%28aeronautics%29" class="Z3988"></span></span> </li> <li id="cite_note-JO711066D-14"><span class="mw-cite-backlink">^ <a href="#cite_ref-JO711066D_14-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-JO711066D_14-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-JO711066D_14-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFFederal_Aviation_Administration" class="citation web cs1">Federal Aviation Administration. <a rel="nofollow" class="external text" href="https://www.faa.gov/regulations_policies/orders_notices/index.cfm/go/document.information/documentID/1040351">"JO 7110.66D, National Beacon Code Allocation Plan"</a>. 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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 href="/wiki/Airborne_collision_avoidance_system" title="Airborne collision avoidance system">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 class="mw-selflink selflink">Transponder</a></li> <li><a href="/wiki/Turn_and_slip_indicator" title="Turn and slip indicator">Turn and slip indicator</a></li> <li><a href="/wiki/Variometer" title="Variometer">Variometer</a></li> <li><a href="/wiki/Yaw_string" title="Yaw string">Yaw string</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Aircraft_engine" title="Aircraft engine">Propulsion</a> controls,<br /> devices and <a href="/wiki/Aircraft_fuel_system" title="Aircraft fuel system">fuel systems</a></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/Autothrottle" title="Autothrottle">Autothrottle</a></li> <li><a href="/wiki/Drop_tank" title="Drop tank">Drop tank</a></li> <li><a href="/wiki/FADEC" title="FADEC">FADEC</a></li> <li><a href="/wiki/Fuel_tank#Aircraft" title="Fuel tank">Fuel tank</a></li> <li><a href="/wiki/Gascolator" title="Gascolator">Gascolator</a></li> <li><a href="/wiki/Inlet_cone" title="Inlet cone">Inlet cone</a></li> <li><a href="/wiki/Intake_ramp" title="Intake ramp">Intake ramp</a></li> <li><a href="/wiki/NACA_cowling" title="NACA cowling">NACA cowling</a></li> <li><a href="/wiki/NACA_duct" title="NACA duct">NACA duct</a></li> <li><a href="/wiki/Self-sealing_fuel_tank" title="Self-sealing fuel tank">Self-sealing fuel tank</a></li> <li><a href="/wiki/Splitter_plate_(aeronautics)" title="Splitter plate (aeronautics)">Splitter plate</a></li> <li><a href="/wiki/Throttle" title="Throttle">Throttle</a></li> <li><a href="/wiki/Thrust_lever" title="Thrust lever">Thrust lever</a></li> <li><a href="/wiki/Thrust_reversal" title="Thrust reversal">Thrust reversal</a></li> <li><a href="/wiki/Townend_ring" title="Townend ring">Townend ring</a></li> <li><a href="/wiki/War_emergency_power" title="War emergency power">War emergency power</a></li> <li><a href="/wiki/Wet_wing" title="Wet wing">Wet wing</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Landing_gear" title="Landing gear">Landing</a> and <a href="/wiki/Arresting_gear" title="Arresting gear">arresting gear</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/Aircraft_tire" title="Aircraft tire">Aircraft tire</a></li> <li><a href="/wiki/Tailhook" title="Tailhook">Arrestor hook</a></li> <li><a href="/wiki/Autobrake" title="Autobrake">Autobrake</a></li> <li><a href="/wiki/Conventional_landing_gear" title="Conventional landing gear">Conventional landing gear</a></li> <li><a href="/wiki/Drogue_parachute" title="Drogue parachute">Drogue parachute</a></li> <li><a href="/wiki/Landing_gear" title="Landing gear">Landing gear</a></li> <li><a href="/wiki/Landing_gear_extender" title="Landing gear extender">Landing gear extender</a></li> <li><a href="/wiki/Oleo_strut" title="Oleo strut">Oleo strut</a></li> <li><a href="/wiki/Tricycle_landing_gear" title="Tricycle landing gear">Tricycle landing gear</a></li> <li><a href="/wiki/Tundra_tire" title="Tundra tire">Tundra tire</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Escape systems</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/Ejection_seat" title="Ejection seat">Ejection seat</a></li> <li><a href="/wiki/Escape_crew_capsule" title="Escape crew capsule">Escape crew capsule</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Other 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 href="/wiki/Aircraft_lavatory" title="Aircraft lavatory">Aircraft lavatory</a></li> <li><a href="/wiki/Auxiliary_power_unit" title="Auxiliary power unit">Auxiliary power unit</a></li> <li><a href="/wiki/Bleed_air" title="Bleed air">Bleed air system</a></li> <li><a href="/wiki/Deicing_boot" title="Deicing boot">Deicing boot</a></li> <li><a href="/wiki/Emergency_oxygen_system" title="Emergency oxygen system">Emergency oxygen system</a></li> <li><a href="/wiki/Environmental_control_system" title="Environmental control system">Environmental control system</a></li> <li><a href="/wiki/Flight_recorder" title="Flight recorder">Flight recorder</a></li> <li><a href="/wiki/Hydraulic_fluid#Aircraft_hydraulic_systems" title="Hydraulic fluid">Hydraulic system</a></li> <li><a href="/wiki/Ice_protection_system" title="Ice protection system">Ice protection system</a></li> <li><a href="/wiki/In-flight_entertainment" title="In-flight entertainment">In-flight entertainment system</a></li> <li><a href="/wiki/Landing_lights" title="Landing lights">Landing lights</a></li> <li><a href="/wiki/Navigation_light" title="Navigation light">Navigation light</a></li> <li><a href="/wiki/Passenger_service_unit" title="Passenger service unit">Passenger service unit</a></li> <li><a href="/wiki/Ram_air_turbine" title="Ram air turbine">Ram air turbine</a></li></ul> </div></td></tr></tbody></table></div>    </div><noscript><img src="https://login.wikimedia.org/wiki/Special:CentralAutoLogin/start?type=1x1" alt="" width="1" height="1" style="border: none; position: absolute;"></noscript> <div class="printfooter" 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