What is the purpose of a localizer in aviation
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| final approach path |
A
localizer in aviation is a component of the instrument landing system (ILS)
that provides pilots with lateral guidance, or horizontal alignment, during the
final approach to a runway.
It is a ground-based radio navigation system that
transmits two narrow intersecting radio beams, one slightly to the right of the
runway centerline and the other slightly to the left.
The aircraft's localizer
receiver compares the strength of the two beams to determine whether the
aircraft is to the left, right, or on centerline of the runway.
Localizer: An Essential Tool for Aviators
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| ILS diagram simplified |
The
localizer antenna array is typically located at the far end of the runway,
beyond the departure threshold. It consists of several pairs of directional
antennas that radiate the two beams. The beams are narrow, typically about 1.5
degrees wide, to provide precise guidance to the aircraft.
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| The localizer antenna |
To
use the localizer, pilots tune their radios to the appropriate frequency for
the runway they are approaching. The localizer receiver then displays a needle
on the pilot's instrument panel. The needle will deflect to the left if the
aircraft is to the left of centerline, to the right if the aircraft is to the
right of centerline, and to the center if the aircraft is on centerline.
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| localizer needle |
Pilots
use the localizer needle to keep the aircraft aligned with the runway
centerline during the final approach. This is especially important in
low-visibility conditions, such as fog or clouds, when pilots may not be able
to see the runway until they are very close.
The
localizer is one of the most important navigation aids used in aviation. It is
a highly accurate and reliable system that provides pilots with the guidance
they need to land safely in all weather conditions.