page_title: Instrument landing system
section_title: Localizer
hierarchical_section_title: Instrument landing system / Principle of operation / Localizer
caption_attribution_description: Deutsch: Localizer Sender der Landebahn 27R des Flughafens Hannover EDDV. Das Bild zeigt die Rückseite der Antennenanlage. English: ILS Localizer 21-element dipole reflector antenna array, Runway 27R, EDDV Hanover/Langenhagen International Airport. The picture shows the back of the antenna system.
context_page_description: An instrument landing system is a system that works by sending radio waves downrange from the runway end, with aircraft that intercept it using the radio waves to guide them onto the runway.
  It is defined by the International Telecommunication Union as a service provided by a station as follows:
  A radionavigation system which provides aircraft with horizontal and vertical guidance just before and during landing and, at certain fixed points, indicates the distance to the reference point of landing.
  — Article 1.104, ITU Radio Regulations
context_section_description: A localizer (LOC, or LLZ until ICAO standardisation) is an antenna array normally located beyond the departure end of the runway and generally consists of several pairs of directional antennas. 
  The localizer will allow the aircraft to turn and match the aircraft with the runway. After that, the pilots will activate approach phase (APP).
caption: The localizer station for runway 27R at Hannover Airport in Germany
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