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class="vector-toc-text"> <span class="vector-toc-numb">2</span> <span>Automatic direction finder equipment</span> </div> </a> <ul id="toc-Automatic_direction_finder_equipment-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Uses" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Uses"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>Uses</span> </div> </a> <button aria-controls="toc-Uses-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 Uses subsection</span> </button> <ul id="toc-Uses-sublist" class="vector-toc-list"> <li id="toc-Airways" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Airways"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.1</span> <span>Airways</span> </div> </a> <ul id="toc-Airways-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Fixes" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Fixes"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.2</span> <span>Fixes</span> </div> </a> <ul id="toc-Fixes-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Determining_distance_from_an_NDB_station" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Determining_distance_from_an_NDB_station"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.3</span> <span>Determining distance from an NDB station</span> </div> </a> <ul id="toc-Determining_distance_from_an_NDB_station-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-NDB_approaches" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#NDB_approaches"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.4</span> <span>NDB approaches</span> </div> </a> <ul id="toc-NDB_approaches-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Instrument_landing_systems" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Instrument_landing_systems"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.5</span> <span>Instrument landing systems</span> </div> </a> <ul id="toc-Instrument_landing_systems-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Naval_operational_uses" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Naval_operational_uses"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.6</span> <span>Naval operational uses</span> </div> </a> <ul id="toc-Naval_operational_uses-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Antenna_and_signal_characteristics" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Antenna_and_signal_characteristics"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>Antenna and signal characteristics</span> </div> </a> <button aria-controls="toc-Antenna_and_signal_characteristics-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 Antenna and signal characteristics subsection</span> </button> <ul id="toc-Antenna_and_signal_characteristics-sublist" class="vector-toc-list"> <li id="toc-Other_information_transmitted_by_an_NDB" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Other_information_transmitted_by_an_NDB"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.1</span> <span>Other information transmitted by an NDB</span> </div> </a> <ul id="toc-Other_information_transmitted_by_an_NDB-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Common_adverse_effects" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Common_adverse_effects"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>Common adverse effects</span> </div> </a> <ul id="toc-Common_adverse_effects-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Monitoring_NDBs" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Monitoring_NDBs"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>Monitoring NDBs</span> </div> </a> <ul id="toc-Monitoring_NDBs-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Beacon_closures" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Beacon_closures"> <div class="vector-toc-text"> <span class="vector-toc-numb">7</span> <span>Beacon closures</span> </div> </a> <ul id="toc-Beacon_closures-sublist" class="vector-toc-list"> </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">8</span> <span>See also</span> </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Notes" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Notes"> <div class="vector-toc-text"> <span class="vector-toc-numb">9</span> <span>Notes</span> </div> </a> <ul id="toc-Notes-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">10</span> <span>References</span> </div> </a> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Further_reading" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Further_reading"> <div class="vector-toc-text"> <span class="vector-toc-numb">11</span> <span>Further reading</span> </div> </a> <ul id="toc-Further_reading-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" href="#External_links"> <div class="vector-toc-text"> <span class="vector-toc-numb">12</span> <span>External links</span> </div> </a> <ul id="toc-External_links-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Contents" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" title="Table of Contents" > <input 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> <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 21 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-21" 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">21 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-af mw-list-item"><a href="https://af.wikipedia.org/wiki/Ongerigte_radiobaken" title="Ongerigte radiobaken – Afrikaans" lang="af" hreflang="af" data-title="Ongerigte radiobaken" data-language-autonym="Afrikaans" data-language-local-name="Afrikaans" class="interlanguage-link-target"><span>Afrikaans</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/NDB_(radiomaj%C3%A1k)" title="NDB (radiomaják) – Czech" lang="cs" hreflang="cs" data-title="NDB (radiomaják)" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Ungerichtetes_Funkfeuer" title="Ungerichtetes Funkfeuer – German" lang="de" hreflang="de" data-title="Ungerichtetes Funkfeuer" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-et mw-list-item"><a href="https://et.wikipedia.org/wiki/Ringsuunaline_raadiomajakas" title="Ringsuunaline raadiomajakas – Estonian" lang="et" hreflang="et" data-title="Ringsuunaline raadiomajakas" data-language-autonym="Eesti" data-language-local-name="Estonian" class="interlanguage-link-target"><span>Eesti</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Baliza_no_direccional" title="Baliza no direccional – Spanish" lang="es" hreflang="es" data-title="Baliza no direccional" 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%A8%DB%8C%DA%A9%D9%88%D9%86_%D8%BA%DB%8C%D8%B1%D8%AC%D9%87%D8%AA%E2%80%8C%D8%AF%D8%A7%D8%B1" title="بیکون غیرجهت‌دار – Persian" lang="fa" hreflang="fa" data-title="بیکون غیرجهت‌دار" 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/Balise_non_directionnelle" title="Balise non directionnelle – French" lang="fr" hreflang="fr" data-title="Balise non directionnelle" 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/%EB%AC%B4%EC%A7%80%ED%96%A5%EC%84%B1_%ED%91%9C%EC%A7%80" title="무지향성 표지 – Korean" lang="ko" hreflang="ko" data-title="무지향성 표지" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-id mw-list-item"><a href="https://id.wikipedia.org/wiki/Non_Directional_Beacon" title="Non Directional Beacon – Indonesian" lang="id" hreflang="id" data-title="Non Directional Beacon" data-language-autonym="Bahasa Indonesia" data-language-local-name="Indonesian" class="interlanguage-link-target"><span>Bahasa Indonesia</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Non-directional_beacon" title="Non-directional beacon – Italian" lang="it" hreflang="it" data-title="Non-directional beacon" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/Non-directional_beacon" title="Non-directional beacon – Dutch" lang="nl" hreflang="nl" data-title="Non-directional beacon" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/%E7%84%A1%E6%8C%87%E5%90%91%E6%80%A7%E7%84%A1%E7%B7%9A%E6%A8%99%E8%AD%98" title="無指向性無線標識 – Japanese" lang="ja" hreflang="ja" data-title="無指向性無線標識" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-no mw-list-item"><a href="https://no.wikipedia.org/wiki/NDB" title="NDB – Norwegian Bokmål" lang="nb" hreflang="nb" data-title="NDB" data-language-autonym="Norsk bokmål" data-language-local-name="Norwegian Bokmål" class="interlanguage-link-target"><span>Norsk bokmål</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/Radiolatarnia_bezkierunkowa" title="Radiolatarnia bezkierunkowa – Polish" lang="pl" hreflang="pl" data-title="Radiolatarnia bezkierunkowa" data-language-autonym="Polski" data-language-local-name="Polish" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/Radiofarol_n%C3%A3o_direcional" title="Radiofarol não direcional – Portuguese" lang="pt" hreflang="pt" data-title="Radiofarol não direcional" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%9F%D1%80%D0%B8%D0%B2%D0%BE%D0%B4%D0%BD%D0%B0%D1%8F_%D1%80%D0%B0%D0%B4%D0%B8%D0%BE%D1%81%D1%82%D0%B0%D0%BD%D1%86%D0%B8%D1%8F" title="Приводная радиостанция – Russian" lang="ru" hreflang="ru" data-title="Приводная радиостанция" 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/Suuntaamaton_radiomajakka" title="Suuntaamaton radiomajakka – Finnish" lang="fi" hreflang="fi" data-title="Suuntaamaton radiomajakka" data-language-autonym="Suomi" data-language-local-name="Finnish" class="interlanguage-link-target"><span>Suomi</span></a></li><li class="interlanguage-link interwiki-sv mw-list-item"><a href="https://sv.wikipedia.org/wiki/Non-directional_beacon" title="Non-directional beacon – Swedish" lang="sv" hreflang="sv" data-title="Non-directional beacon" data-language-autonym="Svenska" data-language-local-name="Swedish" class="interlanguage-link-target"><span>Svenska</span></a></li><li class="interlanguage-link interwiki-tr mw-list-item"><a href="https://tr.wikipedia.org/wiki/NDB_ve_ADF" title="NDB ve ADF – Turkish" lang="tr" hreflang="tr" data-title="NDB ve ADF" data-language-autonym="Türkçe" data-language-local-name="Turkish" class="interlanguage-link-target"><span>Türkçe</span></a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/NDB_(%D0%B0%D0%B2%D1%96%D0%B0%D1%86%D1%96%D1%8F)" title="NDB (авіація) – Ukrainian" lang="uk" hreflang="uk" data-title="NDB (авіація)" data-language-autonym="Українська" data-language-local-name="Ukrainian" class="interlanguage-link-target"><span>Українська</span></a></li><li class="interlanguage-link interwiki-zh mw-list-item"><a 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<div id="vector-page-tools-pinned-container" class="vector-pinned-container"> </div> </nav> <nav class="vector-appearance-landmark" aria-label="Appearance"> <div id="vector-appearance-pinned-container" class="vector-pinned-container"> <div id="vector-appearance" class="vector-appearance vector-pinnable-element"> <div class="vector-pinnable-header vector-appearance-pinnable-header vector-pinnable-header-pinned" data-feature-name="appearance-pinned" data-pinnable-element-id="vector-appearance" data-pinned-container-id="vector-appearance-pinned-container" data-unpinned-container-id="vector-appearance-unpinned-container" > <div class="vector-pinnable-header-label">Appearance</div> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-pin-button" data-event-name="pinnable-header.vector-appearance.pin">move to sidebar</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-appearance.unpin">hide</button> </div> </div> </div> </nav> </div> </div> <div id="bodyContent" class="vector-body" aria-labelledby="firstHeading" data-mw-ve-target-container> <div class="vector-body-before-content"> <div class="mw-indicators"> </div> <div id="siteSub" class="noprint">From Wikipedia, the free encyclopedia</div> </div> <div id="contentSub"><div id="mw-content-subtitle"></div></div> <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">Radio transmitter which emits radio waves in all directions, used as a navigational aid</div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Nkr1.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/c/ca/Nkr1.jpg/220px-Nkr1.jpg" decoding="async" width="220" height="386" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/ca/Nkr1.jpg/330px-Nkr1.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/ca/Nkr1.jpg/440px-Nkr1.jpg 2x" data-file-width="1024" data-file-height="1795" /></a><figcaption>Radio tower of NKR Leimen-Ochsenbach, Germany</figcaption></figure> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Pictogram_NDB.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/1/1b/Pictogram_NDB.svg/220px-Pictogram_NDB.svg.png" decoding="async" width="220" height="220" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/1/1b/Pictogram_NDB.svg/330px-Pictogram_NDB.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/1/1b/Pictogram_NDB.svg/440px-Pictogram_NDB.svg.png 2x" data-file-width="95" data-file-height="95" /></a><figcaption>This symbol denotes an NDB on an <a href="/wiki/Aeronautical_chart" title="Aeronautical chart">aeronautical chart</a>. A hollow square superimposed on this symbol indicates a collocated <a href="/wiki/Distance_measuring_equipment" title="Distance measuring equipment">distance measuring equipment</a> (DME) installation.</figcaption></figure> <p>A <b>non-directional beacon</b> (<b>NDB</b>) or <b>non-directional radio beacon</b> is a <a href="/wiki/Radio_beacon" title="Radio beacon">radio beacon</a> which does not include <em>inherent</em> directional information. Radio beacons are <a href="/wiki/Radio_transmitter" class="mw-redirect" title="Radio transmitter">radio transmitters</a> at a known location, used as an aviation or marine <a href="/wiki/Navigational_aid" title="Navigational aid">navigational aid</a>. NDB are in contrast to directional radio beacons and other navigational aids, such as <a href="/wiki/Low-frequency_radio_range" title="Low-frequency radio range">low-frequency radio range</a>, <a href="/wiki/VHF_omnidirectional_range" title="VHF omnidirectional range">VHF omnidirectional range</a> (VOR) and <a href="/wiki/Tactical_air_navigation_system" title="Tactical air navigation system">tactical air navigation system</a> (TACAN). </p><p>NDB signals <a href="/wiki/Ground_conductivity" title="Ground conductivity">follow the curvature of the Earth</a>, so they can be received at much greater distances at lower altitudes, a major advantage over VOR. However, NDB signals are also affected more by atmospheric conditions, mountainous terrain, coastal refraction and electrical storms, particularly at long range. The system, developed by <a href="/wiki/United_States_Army_Air_Corps" title="United States Army Air Corps">United States Army Air Corps</a> (USAAC) Captain <a href="/wiki/Albert_Francis_Hegenberger" title="Albert Francis Hegenberger">Albert Francis Hegenberger</a>, was used to fly the world's first <a href="/wiki/Instrument_approach" title="Instrument approach">instrument approach</a> on May 9, 1932.<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> </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Types_of_NDBs">Types of NDBs</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Non-directional_beacon&action=edit&section=1" title="Edit section: Types of NDBs"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>NDBs used for aviation are standardised by the <a href="/wiki/International_Civil_Aviation_Organization" title="International Civil Aviation Organization">International Civil Aviation Organization</a> (ICAO) Annex 10 which specifies that NDBs be operated on a frequency between 190 <a href="/wiki/Hertz" title="Hertz">kHz</a> and 1750 kHz,<sup id="cite_ref-FAAAIM_2-0" class="reference"><a href="#cite_note-FAAAIM-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> although normally all NDBs in North America operate between 190 kHz and 535 kHz.<sup id="cite_ref-FAAAIM_2-1" class="reference"><a href="#cite_note-FAAAIM-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> Each NDB is identified by a one, two, or three-letter <a href="/wiki/Morse_code" title="Morse code">Morse code</a> callsign. In Canada, privately owned NDB identifiers consist of one letter and one number. </p><p>Non-directional beacons in North America are classified by power output: "low" power rating is less than 50 <a href="/wiki/Watt" title="Watt">watts</a>; "medium" from 50 W to 2,000 W; and "high" at more than 2,000 W.<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> </p><p>There are four types of non-directional beacons in the aeronautical navigation service:<sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </p> <ul><li>En route NDBs, used to mark airways</li> <li>Approach NDBs</li> <li>Localizer beacons</li> <li>Locator beacons</li></ul> <p>The last two types are used in conjunction with an <a href="/wiki/Instrument_landing_system" title="Instrument landing system">instrument landing system</a> (ILS). </p> <div class="mw-heading mw-heading2"><h2 id="Automatic_direction_finder_equipment">Automatic direction finder equipment</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Non-directional_beacon&action=edit&section=2" title="Edit section: Automatic direction finder equipment"><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">Main article: <a href="/wiki/Automatic_direction_finder" title="Automatic direction finder">Automatic direction finder</a></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Adf_mdi.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/6/67/Adf_mdi.svg/220px-Adf_mdi.svg.png" decoding="async" width="220" height="152" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/67/Adf_mdi.svg/330px-Adf_mdi.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/67/Adf_mdi.svg/440px-Adf_mdi.svg.png 2x" data-file-width="288" data-file-height="199" /></a><figcaption><a href="/wiki/Automatic_direction_finder" title="Automatic direction finder">Automatic direction finder</a> (ADF) equipment points to the direction of an NDB.</figcaption></figure> <p>NDB navigation consists of two parts — the <i><a href="/wiki/Automatic_direction_finder" title="Automatic direction finder">automatic direction finder</a></i> (ADF) equipment on the aircraft that detects an NDB's signal, and the NDB transmitter.<sup id="cite_ref-:0_5-0" class="reference"><a href="#cite_note-:0-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> The ADF can also locate transmitters in the standard <a href="/wiki/AM_broadcasting" title="AM broadcasting">AM</a> <a href="/wiki/Medium_wave" title="Medium wave">medium wave</a> broadcast band (530 kHz to 1700 kHz at 10 kHz increments in the Americas<sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>a<span class="cite-bracket">]</span></a></sup>, 531 kHz to 1602 kHz at 9 kHz increments in the rest of the world). </p><p>ADF equipment determines the direction or bearing to the NDB station relative to the aircraft by using a combination of directional and non-directional antennae to sense the direction in which the combined signal is strongest. This bearing may be displayed on a relative bearing indicator (RBI). This display looks like a compass card with a needle superimposed, except that the card is fixed with the 0 degree position corresponding to the centreline of the aircraft. In order to track toward an NDB (with no wind), the aircraft is flown so that the needle points to the 0 degree position. The aircraft will then fly directly to the NDB. Similarly, the aircraft will track directly away from the NDB if the needle is maintained on the 180 degree mark. With a crosswind, the needle must be maintained to the left or right of the 0 or 180 position by an amount corresponding to the drift due to the crosswind. </p><p>The formula to determine the compass heading to an NDB station (in a no wind situation) is to take the relative bearing between the aircraft and the station, and add the magnetic heading of the aircraft; if the total is greater than 360 degrees, then 360 must be subtracted. This gives the magnetic bearing that must be flown: (RB + MH) <a href="/wiki/Modulo_operation" class="mw-redirect" title="Modulo operation">mod</a> 360 = MB. </p><p>When tracking to or from an NDB, it is also usual that the aircraft track on a specific bearing. To do this it is necessary to correlate the RBI reading with the compass heading. Having determined the drift, the aircraft must be flown so that the compass heading is the required bearing adjusted for drift at the same time as the RBI reading is 0 or 180 adjusted for drift. An NDB may also be used to locate a position along the aircraft's current track (such as a radial path from a second NDB or a VOR). When the needle reaches an RBI reading corresponding to the required bearing, then the aircraft is at the position. However, using a separate RBI and compass, this requires considerable mental calculation to determine the appropriate relative bearing.<sup id="cite_ref-:0_5-1" class="reference"><a href="#cite_note-:0-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> </p><p>To simplify this task, a compass card driven by the aircraft's magnetic compass is added to the RBI to form a <a href="/wiki/Radio_magnetic_indicator" class="mw-redirect" title="Radio magnetic indicator">radio magnetic indicator</a> (RMI). The ADF needle is then referenced immediately to the aircraft's magnetic heading, which reduces the necessity for mental calculation. Many RMIs used for aviation also allow the device to display information from a second radio tuned to a <a href="/wiki/VHF_omnidirectional_range" title="VHF omnidirectional range">VOR</a> station; the aircraft can then fly directly between VOR stations (so-called "Victor" routes) while using the NDBs to triangulate their position along the radial, without the need for the VOR station to have a collocated <a href="/wiki/Distance_measuring_equipment" title="Distance measuring equipment">distance measuring equipment</a> (DME). This display, along with the <a href="/wiki/Course_deviation_indicator" title="Course deviation indicator">omni bearing indicator</a> (OBI) for VOR/ILS information, was one of the primary <a href="/wiki/Radio_navigation" title="Radio navigation">radio navigation</a> instruments prior to the introduction of the <a href="/wiki/Horizontal_situation_indicator" title="Horizontal situation indicator">horizontal situation indicator</a> (HSI) and subsequent digital displays used in <a href="/wiki/Glass_cockpit" title="Glass cockpit">glass cockpits</a>. </p><p>The principles of ADFs are not limited to NDB usage; such systems are also used to detect the locations of broadcast signals for many other purposes, such as finding emergency beacons.<sup id="cite_ref-:0_5-2" class="reference"><a href="#cite_note-:0-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Uses">Uses</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Non-directional_beacon&action=edit&section=3" title="Edit section: Uses"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading3"><h3 id="Airways">Airways</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Non-directional_beacon&action=edit&section=4" title="Edit section: Airways"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:JW_NDB_transmitter_329.0kHz.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/en/thumb/3/3c/JW_NDB_transmitter_329.0kHz.jpg/220px-JW_NDB_transmitter_329.0kHz.jpg" decoding="async" width="220" height="293" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/3/3c/JW_NDB_transmitter_329.0kHz.jpg/330px-JW_NDB_transmitter_329.0kHz.jpg 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/3/3c/JW_NDB_transmitter_329.0kHz.jpg/440px-JW_NDB_transmitter_329.0kHz.jpg 2x" data-file-width="1200" data-file-height="1600" /></a><figcaption>NDB transmitter at <span class="geo-inline"><style data-mw-deduplicate="TemplateStyles:r1156832818">.mw-parser-output .geo-default,.mw-parser-output .geo-dms,.mw-parser-output .geo-dec{display:inline}.mw-parser-output .geo-nondefault,.mw-parser-output .geo-multi-punct,.mw-parser-output .geo-inline-hidden{display:none}.mw-parser-output .longitude,.mw-parser-output .latitude{white-space:nowrap}</style><span class="plainlinks nourlexpansion"><a class="external text" href="https://geohack.toolforge.org/geohack.php?pagename=Non-directional_beacon&params=49_12_21_N_002_13_12_W_type:landmark_region:US&title=Jersey+West"><span class="geo-default"><span class="geo-dms" title="Maps, aerial photos, and other data for this location"><span class="latitude">49°12′21″N</span> <span class="longitude">002°13′12″W</span></span></span><span class="geo-multi-punct"> / </span><span class="geo-nondefault"><span class="vcard"><span class="geo-dec" title="Maps, aerial photos, and other data for this location">49.20583°N 2.22000°W</span><span style="display:none"> / <span class="geo">49.20583; -2.22000</span></span><span style="display:none"> (<span class="fn org">Jersey West</span>)</span></span></span></a></span></span> Callsign JW – 'Jersey West'. 329.0 kHz.</figcaption></figure> <p>A <a href="/wiki/Bearing_(angle)" class="mw-redirect" title="Bearing (angle)">bearing</a> is a line passing through the station that points in a specific direction, such as 270 degrees (due west). NDB bearings provide a charted, consistent method for defining paths aircraft can fly. In this fashion, NDBs can, like VORs, define <a href="/wiki/Airway_(aviation)" title="Airway (aviation)">airways</a> in the sky. Aircraft follow these pre-defined routes to complete a <a href="/wiki/Flight_plan" title="Flight plan">flight plan</a>. Airways are numbered and standardized on charts. Colored airways are used for low to medium frequency stations like the NDB and are charted in brown on sectional charts. Green and red airways are plotted east and west, while amber and blue airways are plotted north and south. As of September 2022, only one colored airway is left in the continental United States, located off the coast of <a href="/wiki/North_Carolina" title="North Carolina">North Carolina</a> and is called G13 or Green 13. Alaska is the only other state in the United States to make use of the colored airway systems.<sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> Pilots follow these routes by tracking bearings across various navigation stations, and turning at some. While most airways in the United States are based on VORs, NDB airways are common elsewhere, especially in the developing world and in lightly populated areas of developed countries, like the <a href="/wiki/Northern_Canada" title="Northern Canada">Canadian Arctic</a>, since they can have a long range and are much less expensive to operate than VORs.<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. (September 2022)">citation needed</span></a></i>]</sup> </p><p>All standard airways are plotted on <a href="/wiki/Aeronautical_chart" title="Aeronautical chart">aeronautical charts</a>, such as the United States <a href="/wiki/Sectional_chart" class="mw-redirect" title="Sectional chart">sectional charts</a>, issued by the <a href="/wiki/National_Oceanic_and_Atmospheric_Administration" title="National Oceanic and Atmospheric Administration">National Oceanic and Atmospheric Administration</a> (NOAA). </p> <div class="mw-heading mw-heading3"><h3 id="Fixes">Fixes</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Non-directional_beacon&action=edit&section=5" title="Edit section: Fixes"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>NDBs have long been used by aircraft <a href="/wiki/Navigator" title="Navigator">navigators</a>, and previously mariners, to help obtain a <a href="/wiki/Geopositioning#Background" title="Geopositioning">fix</a> of their geographic location on the surface of the Earth. Fixes are computed by extending lines through known navigational reference points until they intersect. For visual reference points, the angles of these lines can be determined by <a href="/wiki/Compass" title="Compass">compass</a>; the bearings of NDB radio signals are found using <a href="/wiki/Direction_finding" title="Direction finding">radio direction finder</a> (RDF) equipment. </p> <figure class="mw-default-size mw-halign-center" typeof="mw:File"><a href="/wiki/File:NDB_Article_Airspace_Fix_Diagram.png" class="mw-file-description" title="Airspace Fix Diagram"><img alt="Airspace Fix Diagram" src="//upload.wikimedia.org/wikipedia/commons/7/7c/NDB_Article_Airspace_Fix_Diagram.png" decoding="async" width="147" height="111" class="mw-file-element" data-file-width="147" data-file-height="111" /></a><figcaption>Airspace Fix Diagram</figcaption></figure> <p>Plotting fixes in this manner allow crews to determine their position. This usage is important in situations where other navigational equipment, such as <a href="/wiki/VHF_omnidirectional_range" title="VHF omnidirectional range">VORs</a> with <a href="/wiki/Distance_measuring_equipment" title="Distance measuring equipment">distance measuring equipment</a> (DME), have failed. In marine navigation, NDBs may still be useful should <a href="/wiki/Global_Positioning_System" title="Global Positioning System">Global Positioning System</a> (GPS) reception fail. </p> <div class="mw-heading mw-heading3"><h3 id="Determining_distance_from_an_NDB_station">Determining distance from an NDB station</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Non-directional_beacon&action=edit&section=6" title="Edit section: Determining distance from an NDB station"><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">See also: <a href="/wiki/1_in_60_rule" title="1 in 60 rule">1 in 60 rule</a></div> <p>To determine the distance to an NDB station, the pilot uses this method: </p> <ol><li>Turns the aircraft so that the station is directly off one of the wingtips.</li> <li>Flies that heading, timing how long it takes to cross a specific number of NDB bearings.</li> <li>Uses the formula: Time to station = 60 × number of minutes flown / degrees of bearing change</li> <li>Computes the distance the aircraft is from the station; time × speed = distance</li></ol> <div class="mw-heading mw-heading3"><h3 id="NDB_approaches">NDB approaches</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Non-directional_beacon&action=edit&section=7" title="Edit section: NDB approaches"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>A runway equipped with NDB or VOR (or both) as the only navigation aid is called a non-precision approach runway; if it is equipped with ILS, it is called a precision approach runway. </p> <div class="mw-heading mw-heading3"><h3 id="Instrument_landing_systems">Instrument landing systems</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Non-directional_beacon&action=edit&section=8" title="Edit section: Instrument landing systems"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>NDBs are most commonly used as markers or "locators" for an <a href="/wiki/Instrument_landing_system" title="Instrument landing system">instrument landing system</a> (ILS) approach or standard approach. NDBs may designate the starting area for an ILS approach or a path to follow for a <a href="/wiki/Standard_terminal_arrival_route" title="Standard terminal arrival route">standard terminal arrival route</a>, or STAR. In the United States, an NDB is often combined with the outer <a href="/wiki/Marker_beacon" title="Marker beacon">marker beacon</a> in the ILS approach (called a <a href="/wiki/Marker_beacon#Locator_outer_marker" title="Marker beacon">locator outer marker</a>, or LOM); in Canada, low-powered NDBs have replaced marker beacons entirely. Marker beacons on ILS approaches are now being phased out worldwide with DME ranges or GPS signals used, instead, to delineate the different segments of the approach.<sup id="cite_ref-:0_5-3" class="reference"><a href="#cite_note-:0-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Naval_operational_uses">Naval operational uses</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Non-directional_beacon&action=edit&section=9" title="Edit section: Naval operational uses"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>German Navy <a href="/wiki/U-boat" title="U-boat">U-boats</a> during World War II were equipped with a Telefunken Spez 2113S homing beacon. This transmitter could operate on 100 kHz to 1500 kHz with a power of 150 W. It was used to send the submarine's location to other submarines or aircraft, which were equipped with DF receivers and loop antennas.<sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Antenna_and_signal_characteristics">Antenna and signal characteristics</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Non-directional_beacon&action=edit&section=10" title="Edit section: Antenna and signal characteristics"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Hdl_holzmast1.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/f/f5/Hdl_holzmast1.jpg/220px-Hdl_holzmast1.jpg" decoding="async" width="220" height="293" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/f/f5/Hdl_holzmast1.jpg/330px-Hdl_holzmast1.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/f/f5/Hdl_holzmast1.jpg/440px-Hdl_holzmast1.jpg 2x" data-file-width="1536" data-file-height="2048" /></a><figcaption>One of the wooden poles of NDB HDL at Plankstadt, Germany</figcaption></figure> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Ferritantenne_f%C3%BCr_Ungerichtete_Funkfeueranlagen_NDB.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/2/26/Ferritantenne_f%C3%BCr_Ungerichtete_Funkfeueranlagen_NDB.jpg/220px-Ferritantenne_f%C3%BCr_Ungerichtete_Funkfeueranlagen_NDB.jpg" decoding="async" width="220" height="86" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/2/26/Ferritantenne_f%C3%BCr_Ungerichtete_Funkfeueranlagen_NDB.jpg/330px-Ferritantenne_f%C3%BCr_Ungerichtete_Funkfeueranlagen_NDB.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/2/26/Ferritantenne_f%C3%BCr_Ungerichtete_Funkfeueranlagen_NDB.jpg/440px-Ferritantenne_f%C3%BCr_Ungerichtete_Funkfeueranlagen_NDB.jpg 2x" data-file-width="1077" data-file-height="421" /></a><figcaption>Ferrite antenna for non-directional beacon (NDB), frequency range 255–526.5 kHz</figcaption></figure> <p>NDBs typically operate in the <a href="/wiki/Frequency" title="Frequency">frequency</a> range from 190 kHz to 535 kHz (although they are allocated frequencies from 190 to 1750 kHz) and transmit a carrier <a href="/wiki/Modulation" title="Modulation">modulated</a> by either 400 or 1020 Hz. NDBs can also be collocated with a DME in a similar installation for the ILS as the outer marker, only in this case, they function as the inner marker. NDB owners are mostly governmental agencies and airport authorities. </p><p>NDB radiators are vertically polarised. NDB <a href="/wiki/Antenna_(radio)" title="Antenna (radio)">antennas</a> are usually too short for <a href="/wiki/Resonance" title="Resonance">resonance</a> at the frequency they operate – typically perhaps 20 metres length compared to a <a href="/wiki/Wavelength" title="Wavelength">wavelength</a> around 1000 m. Therefore, they require a suitable matching network that may consist of an inductor and a capacitor to "tune" the antenna. Vertical NDB antennas may also have a <a href="/wiki/T-antenna" title="T-antenna">T-antenna</a>, nicknamed a <i>top hat</i>, which is an umbrella-like structure designed to add loading at the end and improve its radiating efficiency. Usually a <a href="/wiki/Ground_plane" title="Ground plane">ground plane</a> or <a href="/wiki/Counterpoise_(ground_system)" title="Counterpoise (ground system)">counterpoise</a> is connected underneath the antenna. </p> <div class="mw-heading mw-heading3"><h3 id="Other_information_transmitted_by_an_NDB">Other information transmitted by an NDB</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Non-directional_beacon&action=edit&section=11" title="Edit section: Other information transmitted by an NDB"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><span><audio id="mwe_player_0" controls="" preload="none" data-mw-tmh="" class="mw-file-element" width="220" style="width:220px;" data-durationhint="13" data-mwtitle="NonDirectional_Beacon_WG.ogg" data-mwprovider="wikimediacommons" resource="/wiki/File:NonDirectional_Beacon_WG.ogg"><source src="//upload.wikimedia.org/wikipedia/commons/b/b1/NonDirectional_Beacon_WG.ogg" type="audio/ogg; codecs="vorbis"" data-width="0" data-height="0" /><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/b/b1/NonDirectional_Beacon_WG.ogg/NonDirectional_Beacon_WG.ogg.mp3" type="audio/mpeg" data-transcodekey="mp3" data-width="0" data-height="0" /></audio></span><figcaption>The sound of non directional beacon WG, on 248 kHz, located at <span class="geo-inline"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1156832818"><span class="plainlinks nourlexpansion"><a class="external text" href="https://geohack.toolforge.org/geohack.php?pagename=Non-directional_beacon&params=49_53_57.12_N_97_20_57.11_W_type:landmark_region:CA-MB&title=WG"><span class="geo-default"><span class="geo-dms" title="Maps, aerial photos, and other data for this location"><span class="latitude">49°53′57.12″N</span> <span class="longitude">97°20′57.11″W</span></span></span><span class="geo-multi-punct"> / </span><span class="geo-nondefault"><span class="vcard"><span class="geo-dec" title="Maps, aerial photos, and other data for this location">49.8992000°N 97.3491972°W</span><span style="display:none"> / <span class="geo">49.8992000; -97.3491972</span></span><span style="display:none"> (<span class="fn org">WG</span>)</span></span></span></a></span></span>, near <a href="/wiki/Winnipeg_James_Armstrong_Richardson_International_Airport" title="Winnipeg James Armstrong Richardson International Airport">Winnipeg's main airport</a></figcaption></figure> <p>Apart from Morse code identity of either 400 Hz or 1020 Hz, the NDB may broadcast: </p> <ul><li><a href="/wiki/Automatic_terminal_information_service" title="Automatic terminal information service">Automatic terminal information service</a> (ATIS)</li> <li><a href="/w/index.php?title=Automatic_weather_information_service&action=edit&redlink=1" class="new" title="Automatic weather information service (page does not exist)">Automatic weather information service</a> (AWIS), or, in an emergency i.e. <a href="/wiki/Air-to-ground_communication" title="Air-to-ground communication">air-to-ground communication</a> failure, an <a href="/wiki/Air_traffic_controller" title="Air traffic controller">air traffic controller</a> using a <a href="/wiki/Push-to-talk" title="Push-to-talk">push-to-talk</a> (PTT) function, may modulate the carrier with voice. The pilot uses their ADF receiver to hear instructions from the <a href="/wiki/Air_traffic_control" title="Air traffic control">control tower</a>.</li> <li><a href="/wiki/Automated_airport_weather_station#Automated_weather_observing_system_(AWOS)" title="Automated airport weather station">Automated weather observing system</a> (AWOS)</li> <li><a href="/wiki/Automated_airport_weather_station#Automated_surface_observing_system_(ASOS)" title="Automated airport weather station">Automated surface observing system</a> (ASOS)</li> <li><a href="/wiki/VOLMET" title="VOLMET">VOLMET</a> (meteorological information for aircraft in flight) or meteorological information broadcast</li> <li><a href="/w/index.php?title=Transcribed_weather_broadcast&action=edit&redlink=1" class="new" title="Transcribed weather broadcast (page does not exist)">Transcribed weather broadcast</a> (TWEB)</li> <li><a href="/w/index.php?title=PIP_(Morse_Code)&action=edit&redlink=1" class="new" title="PIP (Morse Code) (page does not exist)">PIP</a> monitoring. If an NDB has a problem, e.g. lower than normal power output, failure of mains power or standby transmitter is in operation, the NDB may be programmed to transmit an extra 'PIP' (a Morse dot), to alert pilots and others that the beacon may be unreliable for navigation.</li></ul> <div class="mw-heading mw-heading2"><h2 id="Common_adverse_effects">Common adverse effects</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Non-directional_beacon&action=edit&section=12" title="Edit section: Common adverse effects"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Navigation using an ADF to track NDBs is subject to several common effects: </p> <dl><dt>Night effect</dt> <dd>Radio waves reflected back by the <a href="/wiki/Ionosphere" title="Ionosphere">ionosphere</a> can cause <a href="/wiki/Multipath_propagation#Interference" title="Multipath propagation">signal strength fluctuations</a> 30 to 60 NM (56 to 111 km; 35 to 69 mi) from the transmitter, especially just before sunrise and just after sunset. This is more common on frequencies above 350 kHz. Because the returning sky waves travel over a different path, they have a different phase from the ground wave. This has the effect of suppressing the aerial signal in a fairly random manner. The needle on the indicator will start wandering. The indication will be most erratic during twilight at dusk and dawn.</dd> <dt>Terrain effect</dt> <dd>High terrain like mountains and cliffs can reflect radio waves, giving erroneous readings. Magnetic deposits can also cause erroneous readings</dd> <dt>Thunderstorm effect</dt> <dd>Water droplets and <a href="/wiki/Ice_crystals" class="mw-redirect" title="Ice crystals">ice crystals</a> circulating within a storm cloud, generate wideband noise. This high power noise may affect the accuracy of the ADF bearing. Lightning, due to the high power output will cause the needle of the RMI/RBI to point for a moment to the bearing of the lightning.</dd> <dt>Shoreline effect</dt> <dd>Radio waves speed up over water, causing the wave front to bend away from its normal path and pull it towards the coast.<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. (July 2015)">citation needed</span></a></i>]</sup> Refraction is negligible perpendicular (90°) to the coast, but increases as the angle of incidence decreases. The effect can be minimised by flying higher or by using NDBs situated nearer the coast.</dd> <dt>Station interference</dt> <dd>Due to congestion of stations in the LF and MF bands, there is the possibility of interference from stations on or near the same frequency. This will cause bearing errors. By day, the use of an NDB within the DOC will normally afford protection from interference. However, at night one can expect interference even within the DOC because of skywave contamination from stations out of range by day. Therefore, positive identification of the NDB at night should always be carried out.</dd> <dt>Dip (bank) angle</dt> <dd>During banking turns in an aircraft, the horizontal part of the loop aerial will no longer be horizontal and detect a signal. This causes displacement of the null in a way similar to the night effect giving an erroneous reading on the indicator which means that the pilot should not obtain a bearing unless the aircraft is wings-level.</dd></dl> <p>While pilots study these effects during initial training, trying to compensate for them in flight is very difficult; instead, pilots generally simply choose a heading that seems to average out any fluctuations. </p><p>Radio-navigation aids must keep a certain degree of accuracy, given by international standards, <a href="/wiki/Federal_Aviation_Administration" title="Federal Aviation Administration">Federal Aviation Administration</a> (FAA), ICAO, etc.; to assure this is the case, <a href="/wiki/Flight_inspection" title="Flight inspection">Flight inspection</a> organizations periodically check critical parameters with properly equipped aircraft to calibrate and certify NDB precision. The ICAO minimum accuracy for NDBs is ±5° </p> <div class="mw-heading mw-heading2"><h2 id="Monitoring_NDBs">Monitoring NDBs</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Non-directional_beacon&action=edit&section=13" title="Edit section: Monitoring NDBs"><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">Further information: <a href="/wiki/DXing" title="DXing">DXing</a></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:LVO-397-qsl_card.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/8/86/LVO-397-qsl_card.png/220px-LVO-397-qsl_card.png" decoding="async" width="220" height="138" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/8/86/LVO-397-qsl_card.png/330px-LVO-397-qsl_card.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/8/86/LVO-397-qsl_card.png/440px-LVO-397-qsl_card.png 2x" data-file-width="1780" data-file-height="1120" /></a><figcaption> A PFC <a href="/wiki/QSL_card" title="QSL card">QSL card</a> from an NDB</figcaption></figure> <p>Besides their use in aircraft navigation, NDBs are also popular with long-distance radio enthusiasts (<i>DXers</i>). Because NDBs are generally low-power (usually 25 watts, some can be up to 5 kW), they normally cannot be heard over long distances, but favorable conditions in the <a href="/wiki/Ionosphere" title="Ionosphere">ionosphere</a> can allow NDB signals to travel much farther than normal. Because of this, radio DXers interested in picking up distant signals enjoy listening to faraway NDBs. Also, since the band allocated to NDBs is free of broadcast stations and their associated interference, and because most NDBs do little more than transmit their Morse code callsign, they are very easy to identify, making NDB monitoring an active niche within the <a href="/wiki/DXing" title="DXing">DXing</a> hobby. </p><p>In North America, the NDB band is from 190 to 435 kHz and from 510 to 530 kHz. In Europe, there is a <a href="/wiki/Longwave" title="Longwave">longwave broadcasting band</a> from 150 to 280 kHz, so the European NDB band is from 280 kHz to 530 kHz with a gap between 495 and 505 kHz because <a href="/wiki/500_kHz" title="500 kHz">500 kHz</a> was the <a href="/wiki/International_distress_frequency" title="International distress frequency">international maritime distress (emergency) frequency</a>. </p><p>The beacons that transmit between 510 kHz and 530 kHz can sometimes be heard on AM radios that can tune below the beginning of the <a href="/wiki/Medium_wave" title="Medium wave">medium wave</a> (MW) broadcast band. However, reception of NDBs generally requires a radio receiver that can receive frequencies below 530 kHz. Often "general coverage" shortwave radios receive all frequencies from 150 kHz to 30 MHz, and so can tune to the frequencies of NDBs. Specialized techniques (receiver preselectors, noise limiters and filters) are required for the reception of very weak signals from remote beacons.<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> </p><p>The best time to hear NDBs that are very far away is the last three hours before sunrise. Reception of NDBs is also usually best during the fall and winter because during the spring and summer, there is more atmospheric noise on the <a href="/wiki/Low_frequency" title="Low frequency">LF</a> and <a href="/wiki/Medium_frequency" title="Medium frequency">MF</a> bands. </p> <div class="mw-heading mw-heading2"><h2 id="Beacon_closures">Beacon closures</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Non-directional_beacon&action=edit&section=14" title="Edit section: Beacon closures"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>As the adoption of <a href="/wiki/Satellite_navigation" title="Satellite navigation">satellite navigation</a> systems such as GPS progressed, several countries began to decommission beacon installations such as NDBs and VOR. The policy has caused controversy in the aviation industry.<sup id="cite_ref-Australian_11-0" class="reference"><a href="#cite_note-Australian-11"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> </p><p><a href="/wiki/Airservices_Australia" title="Airservices Australia">Airservices Australia</a> began shutting down a number of ground-based navigation aids in May 2016, including NDBs, VORs and DMEs.<sup id="cite_ref-Australian_11-1" class="reference"><a href="#cite_note-Australian-11"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> </p><p>In the United States as of 2017, there were more than 1,300 NDBs, of which fewer than 300 were owned by the Federal Government. The FAA had begun decommissioning stand-alone NDBs.<sup id="cite_ref-2017_Fed_12-0" class="reference"><a href="#cite_note-2017_Fed-12"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> As of April 2018, the FAA had disabled 23 ground-based navaids including NDBs, and plans to shut down more than 300 by 2025. The FAA has no sustaining or acquisition system for NDBs and plans to phase out the existing NDBs through attrition, citing decreased pilot reliance on NDBs as more pilots use VOR and GPS navigation.<sup id="cite_ref-13" class="reference"><a href="#cite_note-13"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> </p> <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=Non-directional_beacon&action=edit&section=15" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Cardioid" title="Cardioid">Cardioid</a></li> <li><a href="/wiki/Differential_Global_Positioning_System" class="mw-redirect" title="Differential Global Positioning System">Differential Global Positioning System</a> (DGPS)</li> <li><a href="/wiki/Electric_beacon" class="mw-redirect" title="Electric beacon">Electric beacon</a></li> <li><a href="/wiki/Instrument_flight_rules" title="Instrument flight rules">Instrument flight rules</a> (IFR)</li> <li><a href="/wiki/Transponder_landing_system" title="Transponder landing system">Transponder landing system</a> (TLS)</li></ul> <div class="mw-heading mw-heading2"><h2 id="Notes">Notes</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Non-directional_beacon&action=edit&section=16" title="Edit section: Notes"><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-lower-alpha"> <div class="mw-references-wrap"><ol class="references"> <li id="cite_note-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-7">^</a></b></span> <span class="reference-text">Frequencies in this band are not authorized for navigation. NDB stations do not continuously identify themselves, and these waves are more likely to be subject to <a href="/wiki/Skywave" title="Skywave">skywave propagation</a>, especially during the night time.<sup id="cite_ref-IFH_6-0" class="reference"><a href="#cite_note-IFH-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup></span> </li> </ol></div></div> <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=Non-directional_beacon&action=edit&section=17" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239543626"><div class="reflist"> <div class="mw-references-wrap mw-references-columns"><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 id="CITEREFSwopes" class="citation web cs1">Swopes, Bryan. <a rel="nofollow" class="external text" href="https://www.thisdayinaviation.com/tag/non-directional-beacon/">"Non Directional Beacon Archives"</a>. <i>This Day in Aviation</i><span class="reference-accessdate">. Retrieved <span class="nowrap">June 4,</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=This+Day+in+Aviation&rft.atitle=Non+Directional+Beacon+Archives&rft.aulast=Swopes&rft.aufirst=Bryan&rft_id=https%3A%2F%2Fwww.thisdayinaviation.com%2Ftag%2Fnon-directional-beacon%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3ANon-directional+beacon" class="Z3988"></span></span> </li> <li id="cite_note-FAAAIM-2"><span class="mw-cite-backlink">^ <a href="#cite_ref-FAAAIM_2-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-FAAAIM_2-1"><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 web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20090904034127/http://www.faa.gov/air_traffic/publications/ATpubs/AIM/Chap1/aim0101.html#1-1-2">"U.S. FAA <i>Aeronautical Information Manual</i> Chapter 1. Section 1. 1-1-2"</a>. <i>Federal Aviation Administration</i>. Archived from <a rel="nofollow" class="external text" href="http://www.faa.gov/air_traffic/publications/atpubs/aim/Chap1/aim0101.html#1-1-2">the original</a> on September 4, 2009<span class="reference-accessdate">. Retrieved <span class="nowrap">April 27,</span> 2008</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Federal+Aviation+Administration&rft.atitle=U.S.+FAA+Aeronautical+Information+Manual+Chapter+1.+Section+1.+1-1-2&rft_id=http%3A%2F%2Fwww.faa.gov%2Fair_traffic%2Fpublications%2Fatpubs%2Faim%2FChap1%2Faim0101.html%231-1-2&rfr_id=info%3Asid%2Fen.wikipedia.org%3ANon-directional+beacon" class="Z3988"></span></span> </li> <li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</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://web.archive.org/web/20000116232938/http://www.allstar.fiu.edu/aero/ADF.htm">"ADF (Automatic Direction Finder)"</a>. <i>Navigation Systems – Level 3</i>. ALLSTAR Network. May 4, 2008. Archived from <a rel="nofollow" class="external text" href="http://www.allstar.fiu.edu/aero/ADF.htm">the original</a> on January 16, 2000<span class="reference-accessdate">. Retrieved <span class="nowrap">October 17,</span> 2010</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Navigation+Systems+%E2%80%93+Level+3&rft.atitle=ADF+%28Automatic+Direction+Finder%29&rft.date=2008-05-04&rft_id=http%3A%2F%2Fwww.allstar.fiu.edu%2Faero%2FADF.htm&rfr_id=info%3Asid%2Fen.wikipedia.org%3ANon-directional+beacon" class="Z3988"></span></span> </li> <li id="cite_note-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-4">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFRobert_Connolly2016" class="citation journal cs1">Robert Connolly (February 2016). "Types of NDB". <i>Radio User</i>. <b>11</b> (2): <span class="nowrap">48–</span>49. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/1748-8117">1748-8117</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Radio+User&rft.atitle=Types+of+NDB&rft.volume=11&rft.issue=2&rft.pages=%3Cspan+class%3D%22nowrap%22%3E48-%3C%2Fspan%3E49&rft.date=2016-02&rft.issn=1748-8117&rft.au=Robert+Connolly&rfr_id=info%3Asid%2Fen.wikipedia.org%3ANon-directional+beacon" class="Z3988"></span></span> </li> <li id="cite_note-:0-5"><span class="mw-cite-backlink">^ <a href="#cite_ref-:0_5-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-:0_5-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-:0_5-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-:0_5-3"><sup><i><b>d</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFLatifiyan2022" class="citation journal cs1">Latifiyan, Pouya (2022). "NDB in Aviation". <i>Aviation Telecommunication Specialized Conference</i>. <b>6</b>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Aviation+Telecommunication+Specialized+Conference&rft.atitle=NDB+in+Aviation&rft.volume=6&rft.date=2022&rft.aulast=Latifiyan&rft.aufirst=Pouya&rfr_id=info%3Asid%2Fen.wikipedia.org%3ANon-directional+beacon" class="Z3988"></span></span> </li> <li id="cite_note-IFH-6"><span class="mw-cite-backlink"><b><a href="#cite_ref-IFH_6-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation book cs1">"Chapter 9. Navigation Systems". <a rel="nofollow" class="external text" href="https://www.faa.gov/sites/faa.gov/files/regulations_policies/handbooks_manuals/aviation/FAA-H-8083-15B.pdf"><i>Instrument Flying Handbook</i></a> <span class="cs1-format">(PDF)</span> (FAA-H-8083-15B ed.). <a href="/wiki/Federal_Aviation_Administration" title="Federal Aviation Administration">Federal Aviation Administration</a> Flight Standards Service. 2012. p. 3.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=Chapter+9.+Navigation+Systems&rft.btitle=Instrument+Flying+Handbook&rft.pages=3&rft.edition=FAA-H-8083-15B&rft.pub=Federal+Aviation+Administration+Flight+Standards+Service&rft.date=2012&rft_id=https%3A%2F%2Fwww.faa.gov%2Fsites%2Ffaa.gov%2Ffiles%2Fregulations_policies%2Fhandbooks_manuals%2Faviation%2FFAA-H-8083-15B.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3ANon-directional+beacon" class="Z3988"></span></span> </li> <li id="cite_note-8"><span class="mw-cite-backlink"><b><a href="#cite_ref-8">^</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.faa.gov/air_traffic/publications/atpubs/aim_html/chap5_section_3.html">"FAA Aeronautical Information Manual, 5-3-4. <i>Airways and Route Systems</i>"</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=FAA+Aeronautical+Information+Manual%2C+5-3-4.+Airways+and+Route+Systems&rft_id=https%3A%2F%2Fwww.faa.gov%2Fair_traffic%2Fpublications%2Fatpubs%2Faim_html%2Fchap5_section_3.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ANon-directional+beacon" class="Z3988"></span></span> </li> <li id="cite_note-9"><span class="mw-cite-backlink"><b><a href="#cite_ref-9">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFRobert_Connolly2010" class="citation journal cs1">Robert Connolly (December 2010). "Beacon Updates and Frequencies to Try". <i>Radio User</i>. <b>5</b> (12): 48. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/1748-8117">1748-8117</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Radio+User&rft.atitle=Beacon+Updates+and+Frequencies+to+Try&rft.volume=5&rft.issue=12&rft.pages=48&rft.date=2010-12&rft.issn=1748-8117&rft.au=Robert+Connolly&rfr_id=info%3Asid%2Fen.wikipedia.org%3ANon-directional+beacon" class="Z3988"></span></span> </li> <li id="cite_note-10"><span class="mw-cite-backlink"><b><a href="#cite_ref-10">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFRemington,_S.,_KH6SR1987–1989" class="citation web cs1">Remington, S., KH6SR (1987–1989). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20180527111627/http://lwca.org/library/articles/kh6sr/">"On the Art of NDB DXing"</a>. The Longwave Club of America. Archived from <a rel="nofollow" class="external text" href="http://lwca.org/library/articles/kh6sr/">the original</a> on May 27, 2018<span class="reference-accessdate">. Retrieved <span class="nowrap">January 6,</span> 2008</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=On+the+Art+of+NDB+DXing&rft.pub=The+Longwave+Club+of+America&rft.date=1987%2F1989&rft.au=Remington%2C+S.%2C+KH6SR&rft_id=http%3A%2F%2Flwca.org%2Flibrary%2Farticles%2Fkh6sr%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3ANon-directional+beacon" class="Z3988"></span><span class="cs1-maint citation-comment"><code class="cs1-code">{{<a href="/wiki/Template:Cite_web" title="Template:Cite web">cite web</a>}}</code>: CS1 maint: multiple names: authors list (<a href="/wiki/Category:CS1_maint:_multiple_names:_authors_list" title="Category:CS1 maint: multiple names: authors list">link</a>) CS1 maint: numeric names: authors list (<a href="/wiki/Category:CS1_maint:_numeric_names:_authors_list" title="Category:CS1 maint: numeric names: authors list">link</a>)</span></span> </li> <li id="cite_note-Australian-11"><span class="mw-cite-backlink">^ <a href="#cite_ref-Australian_11-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Australian_11-1"><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 web cs1"><a rel="nofollow" class="external text" href="https://australianaviation.com.au/2016/05/airservices-to-begin-turning-off-ground-based-navaids-from-may-26/">"Airservices to begin turning off ground-based navaids from May 26"</a>. 26 May 2016.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Airservices+to+begin+turning+off+ground-based+navaids+from+May+26&rft.date=2016-05-26&rft_id=https%3A%2F%2Faustralianaviation.com.au%2F2016%2F05%2Fairservices-to-begin-turning-off-ground-based-navaids-from-may-26%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3ANon-directional+beacon" class="Z3988"></span></span> </li> <li id="cite_note-2017_Fed-12"><span class="mw-cite-backlink"><b><a href="#cite_ref-2017_Fed_12-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFMattisChaoDuke2017" class="citation web cs1">Mattis, James N.; Chao, Elaine L.; Duke, Elaine C. (2017). <a rel="nofollow" class="external text" href="https://rosap.ntl.bts.gov/view/dot/32801">"2017 Federal Radionavigation Plan"</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=2017+Federal+Radionavigation+Plan&rft.date=2017&rft.aulast=Mattis&rft.aufirst=James+N.&rft.au=Chao%2C+Elaine+L.&rft.au=Duke%2C+Elaine+C.&rft_id=https%3A%2F%2Frosap.ntl.bts.gov%2Fview%2Fdot%2F32801&rfr_id=info%3Asid%2Fen.wikipedia.org%3ANon-directional+beacon" class="Z3988"></span></span> </li> <li id="cite_note-13"><span class="mw-cite-backlink"><b><a href="#cite_ref-13">^</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.aopa.org/advocacy/airports-and-airspace/navigation-and-charting/navaid-decommissioning">"NAVAID Decommissioning"</a>. September 17, 2018.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=NAVAID+Decommissioning&rft.date=2018-09-17&rft_id=https%3A%2F%2Fwww.aopa.org%2Fadvocacy%2Fairports-and-airspace%2Fnavigation-and-charting%2Fnavaid-decommissioning&rfr_id=info%3Asid%2Fen.wikipedia.org%3ANon-directional+beacon" class="Z3988"></span></span> </li> </ol></div></div> <div class="mw-heading mw-heading2"><h2 id="Further_reading">Further reading</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Non-directional_beacon&action=edit&section=18" title="Edit section: Further reading"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li>International Civil Aviation Organization (2000). <i>Annex 10 — Aeronautical Telecommunications</i>, Vol. I (Radio Navigation Aids) (5th ed.).</li> <li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20081201074339/http://www1.faa.gov/ATpubs/AIM/">U.S. Federal Aviation Administration (2004). <i>Aeronautical Information Manual</i>, § 1-1-2.</a></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFRemington,_S.,_KH6SR1987–1989" class="citation web cs1">Remington, S., KH6SR (1987–1989). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20021209101109/http://lwca.org/library/articles/kh6sr/index.htm">"On the Art of NDB DXing"</a>. The Longwave Club of America. Archived from <a rel="nofollow" class="external text" href="http://lwca.org/library/articles/kh6sr/index.htm">the original</a> on December 9, 2002<span class="reference-accessdate">. Retrieved <span class="nowrap">January 6,</span> 2008</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=On+the+Art+of+NDB+DXing&rft.pub=The+Longwave+Club+of+America&rft.date=1987%2F1989&rft.au=Remington%2C+S.%2C+KH6SR&rft_id=http%3A%2F%2Flwca.org%2Flibrary%2Farticles%2Fkh6sr%2Findex.htm&rfr_id=info%3Asid%2Fen.wikipedia.org%3ANon-directional+beacon" class="Z3988"></span><span class="cs1-maint citation-comment"><code class="cs1-code">{{<a href="/wiki/Template:Cite_web" title="Template:Cite web">cite web</a>}}</code>: CS1 maint: multiple names: authors list (<a href="/wiki/Category:CS1_maint:_multiple_names:_authors_list" title="Category:CS1 maint: multiple names: authors list">link</a>) CS1 maint: numeric names: authors list (<a href="/wiki/Category:CS1_maint:_numeric_names:_authors_list" title="Category:CS1 maint: numeric names: authors list">link</a>)</span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFAppleyard,_S.F.Linford,_R.S.Yarwood,_P.J.1988" class="citation book cs1">Appleyard, S.F.; Linford, R.S.; Yarwood, P.J. (1988). <i>Marine Electronic Navigation</i> (2nd ed.). Routledge & Kegan Paul. pp. <span class="nowrap">68–</span>69. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/0-7102-1271-2" title="Special:BookSources/0-7102-1271-2"><bdi>0-7102-1271-2</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Marine+Electronic+Navigation&rft.pages=%3Cspan+class%3D%22nowrap%22%3E68-%3C%2Fspan%3E69&rft.edition=2nd&rft.pub=Routledge+%26+Kegan+Paul&rft.date=1988&rft.isbn=0-7102-1271-2&rft.au=Appleyard%2C+S.F.&rft.au=Linford%2C+R.S.&rft.au=Yarwood%2C+P.J.&rfr_id=info%3Asid%2Fen.wikipedia.org%3ANon-directional+beacon" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFGodfrey_Manning2007" class="citation journal cs1">Godfrey Manning (December 2007). "Sky High: ADF and NDBs". <i>Radio User</i>. <b>2</b> (12). PW Publishing Ltd: 25. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/1748-8117">1748-8117</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Radio+User&rft.atitle=Sky+High%3A+ADF+and+NDBs&rft.volume=2&rft.issue=12&rft.pages=25&rft.date=2007-12&rft.issn=1748-8117&rft.au=Godfrey+Manning&rfr_id=info%3Asid%2Fen.wikipedia.org%3ANon-directional+beacon" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFGodfrey_Manning2008" class="citation journal cs1">Godfrey Manning (January 2008). "Sky High: NDB/ADF". <i>Radio User</i>. <b>3</b> (1). PW Publishing Ltd: <span class="nowrap">24–</span>25. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/1748-8117">1748-8117</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Radio+User&rft.atitle=Sky+High%3A+NDB%2FADF&rft.volume=3&rft.issue=1&rft.pages=%3Cspan+class%3D%22nowrap%22%3E24-%3C%2Fspan%3E25&rft.date=2008-01&rft.issn=1748-8117&rft.au=Godfrey+Manning&rfr_id=info%3Asid%2Fen.wikipedia.org%3ANon-directional+beacon" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFRichard_Gosnell2008" class="citation journal cs1">Richard Gosnell (April 2008). "An Introduction to Non Directional Beacons". <i>Radio User</i>. <b>3</b> (4). PW Publishing Ltd: <span class="nowrap">28–</span>29. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/1748-8117">1748-8117</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Radio+User&rft.atitle=An+Introduction+to+Non+Directional+Beacons&rft.volume=3&rft.issue=4&rft.pages=%3Cspan+class%3D%22nowrap%22%3E28-%3C%2Fspan%3E29&rft.date=2008-04&rft.issn=1748-8117&rft.au=Richard+Gosnell&rfr_id=info%3Asid%2Fen.wikipedia.org%3ANon-directional+beacon" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFRobert_Connolly2009" class="citation journal cs1">Robert Connolly (August 2009). "NDB DXing – Understanding the basics". <i>Radio User</i>. <b>4</b> (8). PW Publishing Ltd: <span class="nowrap">40–</span>42. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/1748-8117">1748-8117</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Radio+User&rft.atitle=NDB+DXing+%E2%80%93+Understanding+the+basics&rft.volume=4&rft.issue=8&rft.pages=%3Cspan+class%3D%22nowrap%22%3E40-%3C%2Fspan%3E42&rft.date=2009-08&rft.issn=1748-8117&rft.au=Robert+Connolly&rfr_id=info%3Asid%2Fen.wikipedia.org%3ANon-directional+beacon" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation book cs1"><span class="id-lock-limited" title="Free access subject to limited trial, subscription normally required"><a rel="nofollow" class="external text" href="https://archive.org/details/instrumentproced00admi"><i>Instrument Procedures Handbook FAA-H-8261-1A</i></a></span>. FAA. 2007. pp. <span class="nowrap">5–</span>60. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/9781560276869" title="Special:BookSources/9781560276869"><bdi>9781560276869</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Instrument+Procedures+Handbook+FAA-H-8261-1A&rft.pages=%3Cspan+class%3D%22nowrap%22%3E5-%3C%2Fspan%3E60&rft.pub=FAA&rft.date=2007&rft.isbn=9781560276869&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Finstrumentproced00admi&rfr_id=info%3Asid%2Fen.wikipedia.org%3ANon-directional+beacon" class="Z3988"></span></li></ul> <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=Non-directional_beacon&action=edit&section=19" title="Edit section: External links"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1235681985">.mw-parser-output .side-box{margin:4px 0;box-sizing:border-box;border:1px solid #aaa;font-size:88%;line-height:1.25em;background-color:var(--background-color-interactive-subtle,#f8f9fa);display:flow-root}.mw-parser-output .side-box-abovebelow,.mw-parser-output .side-box-text{padding:0.25em 0.9em}.mw-parser-output .side-box-image{padding:2px 0 2px 0.9em;text-align:center}.mw-parser-output .side-box-imageright{padding:2px 0.9em 2px 0;text-align:center}@media(min-width:500px){.mw-parser-output .side-box-flex{display:flex;align-items:center}.mw-parser-output .side-box-text{flex:1;min-width:0}}@media(min-width:720px){.mw-parser-output .side-box{width:238px}.mw-parser-output .side-box-right{clear:right;float:right;margin-left:1em}.mw-parser-output .side-box-left{margin-right:1em}}</style><style data-mw-deduplicate="TemplateStyles:r1237033735">@media print{body.ns-0 .mw-parser-output .sistersitebox{display:none!important}}@media screen{html.skin-theme-clientpref-night .mw-parser-output .sistersitebox img[src*="Wiktionary-logo-en-v2.svg"]{background-color:white}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .sistersitebox img[src*="Wiktionary-logo-en-v2.svg"]{background-color:white}}</style><div class="side-box side-box-right plainlinks sistersitebox"><style data-mw-deduplicate="TemplateStyles:r1126788409">.mw-parser-output .plainlist ol,.mw-parser-output .plainlist ul{line-height:inherit;list-style:none;margin:0;padding:0}.mw-parser-output .plainlist ol li,.mw-parser-output .plainlist ul li{margin-bottom:0}</style> <div class="side-box-flex"> <div class="side-box-image"><span class="noviewer" typeof="mw:File"><a href="/wiki/File:Commons-logo.svg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/30px-Commons-logo.svg.png" decoding="async" width="30" height="40" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/45px-Commons-logo.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/59px-Commons-logo.svg.png 2x" data-file-width="1024" data-file-height="1376" /></a></span></div> <div class="side-box-text plainlist">Wikimedia Commons has media related to <span style="font-weight: bold; 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mw-ui-icon-wikimedia-speechBubbleAdd-progressive"></span> <span>Add topic</span> </a> </div> <div class="vector-sticky-header-icon-end"> <div class="vector-user-links"> </div> </div> </div> </div> </div> <div class="vector-settings" id="p-dock-bottom"> <ul></ul> </div><script>(RLQ=window.RLQ||[]).push(function(){mw.config.set({"wgHostname":"mw-web.codfw.main-7878cd4448-s845p","wgBackendResponseTime":116,"wgPageParseReport":{"limitreport":{"cputime":"0.406","walltime":"0.530","ppvisitednodes":{"value":1920,"limit":1000000},"postexpandincludesize":{"value":44511,"limit":2097152},"templateargumentsize":{"value":3113,"limit":2097152},"expansiondepth":{"value":13,"limit":100},"expensivefunctioncount":{"value":6,"limit":500},"unstrip-depth":{"value":1,"limit":20},"unstrip-size":{"value":62909,"limit":5000000},"entityaccesscount":{"value":0,"limit":400},"timingprofile":["100.00% 452.597 1 -total"," 33.27% 150.557 2 Template:Reflist"," 25.71% 116.367 9 Template:Cite_web"," 14.31% 64.778 1 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Inc.","logo":{"@type":"ImageObject","url":"https:\/\/www.wikimedia.org\/static\/images\/wmf-hor-googpub.png"}},"datePublished":"2003-09-12T01:35:06Z","dateModified":"2025-01-11T18:05:46Z","image":"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/1\/1b\/Pictogram_NDB.svg","headline":"radio transmitter which emits radio waves in all directions"}</script> </body> </html>