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SESK: Stuff Everyone Should Know · sesk.info/ifr-localizer-width

At the runway threshold, how wide is a localizer course from full-scale left to full-scale right?

700 feet at the runway threshold.

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  1. 300 feet
  2. 700 feet ✔
  3. 1,500 feet

Why: The localizer is adjusted so that full-scale deflection spans 700 feet at the threshold. That is typically a course about 5 degrees wide, so full deflection occurs 2.5 degrees either side and the needle is very sensitive.

Huh, didn't know that: Localizer frequencies are in the range 108.10 to 111.95 MHz.

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The localizer needle is the most honest part of any approach. It never hides its feelings.
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References

Answer: 700 feet. The localizer is adjusted so that full-scale deflection spans 700 feet at the threshold. That is typically a course about 5 degrees wide, so full deflection occurs 2.5 degrees either side and the needle is very sensitive.

  1. FAA Aeronautical Information Manual 1-1 Navigation Aids www.faa.gov/air_traffic/publications/atpubs/aim_html/chap1_section_1.html
    full scale fly-left to a full scale fly-right) of 700 feet at the runway threshold.
    Checked 2026-10-11.
  2. FAA Instrument Flying Handbook (FAA-H-8083-15B) www.faa.gov/sites/faa.gov/files/pilots/FAA-H-8083-15B.pdf
    a full-scale deflection shows when the aircraft is 2.5° to either side
    Checked 2026-10-11.

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