Instrument landing system localizer

In aviation, a localizer (LOC) is one of the components of an Instrument Landing System (ILS), and it provides runway centerline guidance to aircraft. In some cases, a course projected by localizer is at an angle to the runway (usually due to obstructions around the airport). It is then called a Localizer Type Directional Aid (LDA). Localizers also exist in stand-alone instrument approach installations and are not always part of an ILS. The localizer is placed about 1,000 feet from the far end of the approached runway. Its useful volume extends to 18 NM for the path up to 10 degrees either side of the course. For an angle of 35 degrees either side of the course the useful volume of the localizer extends up to 10 NM. Horizontal guidance gets more accurate the closer you fly to the localizer station. Localizer approaches have their specific weather minimums found on approach plates.

Localizer as component of an ILS (KMEZ Runway 27, Mena, Arkansas).

See also

• AN/MRN-1
• Andrew Alford
• Instrument approach
• Instrument landing system
• Simplified Directional Facility
• Localizer Type Directional Aid

References

• Aeronautical Information Manual, published in US by Federal Aviation Administration

External links

• Describes and illustrates localizer antenna and its radiation pattern.
• Describes the localizer receiver of the ILS system, using illustrative figures illustrate a situation that may occur during the approach to the runway