AhaBulbStuff Everyone Should Know
AhaBulb: Stuff Everyone Should Know · ahabulb.com/pilot-altitude-5500-phraseology

What is the correct way to say 5,500 feet MSL to ATC?

Five thousand five hundred.

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  1. Five point five
  2. Five thousand five hundred ✔
  3. Fifty-five hundred feet MSL

Why: The AIM says altitudes below 18,000 feet are spoken in thousands and hundreds, like 'four thousand five hundred.' Above 18,000 feet they become flight levels.

Huh, didn't know that: Radio numbers have special sounds: three is 'tree,' five is 'fife,' and nine is 'niner.'

The dad joke
Why was six afraid of seven? Because seven eight nine.
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References

Answer: Five thousand five hundred. The AIM says altitudes below 18,000 feet are spoken in thousands and hundreds, like 'four thousand five hundred.' Above 18,000 feet they become flight levels.

  1. AIM 4-2 Radio Communications Phraseology and Techniques www.faa.gov/air_traffic/publications/atpubs/aim_html/chap4_section_2.html
    4,500 four thousand five hundred
    Checked 2026-10-09.

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