Wednesday, March 18, 2020



The instrument landing system localizer, or simply localizer (LOC), is used to guide the plane along the runway axis.

Each radio station or system is classified by the Service on which it operates permanently or temporarily.


In aviation, it is combined with a vertical localizer for the runway Centerline (ILS.

Collaboration between a localizer (such as a glideslope) and a transmitter airport runway and receiver. An old aircraft without an ILS receiver cannot take advantage of any ILS facility on any runway, and more importantly, they do not use ILS instruments on runways lacking the most modern aircraft ILS facilities. Major airports in parts of Africa and Asia may have any deficiencies transmitting the ILS system. Some tracks have ILS in only one direction, but this can still be used (with a lower sensitivity) or "back course" not associated with a.


The localizer indicator (on most aircraft produced in the late 1950s) is shown below the attitude indicator, but still part of this instrument along with the glideslope indicator and is called cross in the center of the instrument.

The glideslope scale is to the right of the attitude area. Airplanes with a mechanical gyroscope compass have both a localizer and glideslope, which is shown as a vertical and horizontal arrow on the compass. But they are actually read the same way. The oldest version of the glideslope and ILS instruments specified in only two major instruments in some aircraft was its own instrument used instead. Two hanging rods fixed in the middle of the top (localizer indicator) used and in the middle of the left side (glideslope indicator), and if the plane was located on the intended glidepath, the hanging rods formed a cross. In theory, however, it is more difficult to learn — but even for experienced pilots using such indicators, he added another instrument they needed to focus on. With indicators added to the artificial horizon (and compass), the pilot can theoretically monitor the attitude simultaneously with the localizer and glideslope.

In modern cockpits, the localizer appears as a colored spot (usually in the form of a diamond) at the bottom. . It does not appear during the cruise, but the selected track comes up during landing and approach, the provided navigation radio is tuned to the ILS frequency of this particular track. Usually, but not always, if the localizer beam transmitted, the runway extension header is directed. (exceptions are for example Innsbruck, Austria and Macao, China) If the aircraft is on this line, the localizing point will appear in the middle of the scale. But if the plane is located somewhat in the cockpit of the leftist beam, the marker will appear on the scale of the localizer indicator. The pilot then knows he needs to adjust the Title across.

In the old cockpits, the localizer scale below the artificial horizon is quite short. But in the old-style cockpit instrumentation, the localizer also appears as an arrow, the gyro compass is below the artificial horizon. The top and bottom of this arrow is a "unit" that indicates the current Title. However, the middle part of this arrow moves independently of the cap of the plane. The center of this arrow can be described as "stand-alone" and moves to the right if the aircraft is to the right of the localizer beam and the aircraft is to the left of the localizer beam. When the arrow is "Unified" on a straight line, the aircraft is following the localizer beam. (This second "arrow pointer" is neglected in modern cockpits, but the main compass is still below the artificial horizon)

In the previously mentioned exceptions of the tracks where the ILS beam does not go as far as the runway, the runway must be visible before the final approach begins.

The first generation localizer indicators had a different cockpit interface and were located on the scale of the artificial horizon, not on any compass. The localizer was then represented as a hanging bar hanging from a fixed point above a separate indicator, and the glideslope was represented by a similar, but horizontal, dangling bar fixed to one of the edges of the indicator. When the plane was located exactly on the ILS-beam (or glidepath), the two bars formed a cross. This interface is similar to Flight Director, it also creates a cross, but on the artificial horizon. This old ILS instrumentation system, like Jet aircraft, was also ignored, the Boeing 707 and DC 8 were introduced.

The phrase "Catch the Localizer" refers to the runway approaches with the Autopilot. The angle between the aircraft hood and the localizing beam must be less than 30 degrees and the specified air velocity must be under at least 250 knots (for jet aircraft), then by pressing a button marked "APP" or "ILS", the Autopilot will probably turn and then will follow the localizer. The autopilot will then automatically land according to glideslope. The normal procedure is to catch the localizer first and then follow the glideslope as well. If the angle is too large or the air speed is too high, catching the localizer may fail.

Modern aircraft can land "themselves", provided that the runway ILS is of sufficient standard (class III C) and the cross wind component is low. Autolandings are mostly done in foggy weather.

Cockpit ILS indicators should not be confused with the Flight Director, who also places vertical and horizontal lines on the artificial horizon. A flight manager only shows how the autopilot will fly. If the localizing point (or arrow) shows that the runway will be located on the left, but the Flight Director suggests a right turn and the runway is not visible, the pilot has difficulties.

Some tracks have ILS beams designed for use in one direction only. However, as the localizing beam progresses backward in nature, there may still be some use. This is called back beam. It helps during the approach, but the use of the back beam localizer provides less sensitivity compared to normal use.


When the glideslope is unserviceable, the localizer element can often be carried as a separate non-precision approach, shortened to 'LOC'. The installation of a standalone instrument approach without the associated glidepath bears the abbreviation 'LLZ'.

In some cases, a route prescribed by the localizer is at an angle (usually) to the runway. It is later called a localizer type directional aid (LDA). The localizer system is placed approximately 1000 meters from the far end of the runway approached. The usable volume extends up to 18 NM for a path up to 10 ° on either side of the runway Centerline. At an angle of 35 ° on both sides of the Runway Centerline, the useful volume extends to 10 NM. Horizontal accuracy increases as the distance between the plane and the localizer decreases. The localizer approach has certain weather minimums.

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