Besides the fact that it's now a standard, why do American-English-speaking pilots and ATC say "Niner" instead of "Nine"? None of the other numerals are pronounced in an atypical fashion.

For what was "Nine" being mistaken that resulted in the "Niner" standard being adopted?

  • 16
    $\begingroup$ Not all - only the properly trained ones :-) $\endgroup$ Commented May 20, 2015 at 13:54
  • $\begingroup$ Hmm... I'd say the fact that it's a standard is why pilots use it. It also sounds a lot less weird to a native English speaker than the tree/fower/fife stuff. Those just sound like a non-native incorrectly trying to pronounce three, some unknown word, and five, respectively. :) $\endgroup$
    – reirab
    Commented May 21, 2015 at 4:36
  • $\begingroup$ It's ICAO standard. And certainly with the US military. Actually using it is another thing. And if you've ever used shortwave to communicate you'd get that big "A-Ha". $\endgroup$
    – radarbob
    Commented Feb 8, 2016 at 16:32
  • $\begingroup$ @radarbob Can you elaborate on the shortwave reference? $\endgroup$ Commented Feb 8, 2016 at 23:15
  • 2
    $\begingroup$ Due to the nature of shortwave reception can be weak and/or have lots of noise. Speaking phonetically helps tree-mendously. And often we'd have to phonetically spell, e.g. "Whisky Hotel Alpha Tango". $\endgroup$
    – radarbob
    Commented Feb 8, 2016 at 23:21

4 Answers 4


According to Wikipedia:

The pronunciation of the digits 3, 4, 5, and 9 differs from standard English – being pronounced tree, fower, fife, and niner. The digit 3 is specified as tree so that it is not pronounced sri; the long pronunciation of 4 (still found in some English dialects) keeps it somewhat distinct from for; 5 is pronounced with a second "f" because the normal pronunciation with a "v" is easily confused with "fire" (a command to shoot); and 9 has an extra syllable to keep it distinct from German nein 'no'.

The phonetic alphabet is not a random selection of words. It was created very carefully taking dialects into account, so as not to confuse any of the letter with possible mispronunciations. Although they are "English" words, the choices were made with the world in mind.

As mentioned on the same article:

The final choice of code words for the letters of the alphabet and for the digits was made after hundreds of thousands of comprehension tests involving 31 nationalities.

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    $\begingroup$ @RockPaperLizard Germany as well. Germans struggle with the English "th", it often comes out as "sri" as mentioned above. This is why it is consistently taught as "tree" in Germany for aviation purposes, when English is used in ATC/(A)FIS communication. The Aviation.SE blog will have a series on stuff like this... we are working on it. :) $\endgroup$ Commented May 20, 2015 at 8:57
  • 3
    $\begingroup$ @RockPaperLizard I've known Irishmen who pronounce 3 as "tree". It wouldn't surprise me if the whole country has a similar dialect. $\endgroup$
    – Gabe
    Commented May 20, 2015 at 16:00
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    $\begingroup$ Adding the extra syllable to "foh-er" and "niner" means that the vowel patterns OH, UH, OO, EE, OH-IH, AY, IH, EH-EH, EY, AY-IH, are all distinct even without any consonants. I don't know whether radio static played a role in the choice of phonetics, but I think vowels are often less likely to be misinterpreted than consonants. As for "t" versus "th" for "3", even if the ideal pronunciation were an English "th", some non-English-speakers might say something closer to that if asked to say "t" than if asked to say "th". $\endgroup$
    – supercat
    Commented May 20, 2015 at 16:16
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    $\begingroup$ Surely, "niner" helps to distinguish 9 from 5. I'd've thought that most of the time, context would make it obvious whether you meant fire or 5 or whether you were saying 'no' in German or 9. But it's surely as easy to mistake a 9 for a 5 as it is to mistake a B for a D, say. $\endgroup$
    – Au101
    Commented May 20, 2015 at 16:41
  • 2
    $\begingroup$ @Au101 This is why they went ahead and dont use single letters by themselves, but have the ICAO alphabet: Bravo and Delta. $\endgroup$ Commented May 20, 2015 at 21:42

The reasons I've heard behind the pronunciations:

  • Three / Tree:
    Some non-native English speakers have trouble both pronouncing and understanding the "TH" sound. Tree is better pronounced and better understood by all people, regardless of accent.

  • Five / Fife:
    Much of aviation has a military history. On a poorly heard transmission "Five" can sound a lot like "Fire", which is both a military command to "shoot", and an aviation emergency! "Fife" avoids that ambiguity.

  • Nine / Niner:
    German is a commonly spoken language, and "Nein" (pronounced like "Nine" in English) is "No" in German. To keep it clear that this is a digit and not a negative-reply, "Niner" is distinct from the "Nine"

  • $\begingroup$ I've heard that explosives/demolitions engineers skip "Five" for the same reason, but I can't confirm that with fact, only hearsay. $\endgroup$
    – Steve V.
    Commented May 10, 2017 at 20:15
  • 16
    $\begingroup$ There's a joke of a german pilot asking "May I get local QHN?" ATC: "Nine, nine, nine".. "Und warum nein?" $\endgroup$
    – gusto2
    Commented May 11, 2017 at 9:36
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    $\begingroup$ I truly appreciate your answer. Even if partially anecdotal, it provides significant insight. $\endgroup$ Commented May 12, 2017 at 5:54
  • $\begingroup$ „nein” is “no” in German. “nine” is only pronounced (almost) the same way. $\endgroup$
    – Michael
    Commented Aug 3, 2018 at 7:38
  • 2
    $\begingroup$ At least in the Royal Navy, the word Fire is reserved for when a self-sustaining combustion reaction is ongoing on your vessel. If you want guns to launch things at someone, you say Shoot!. $\endgroup$ Commented Jan 14, 2019 at 15:41

The standard answer is that “nine” could be mistaken for German “nein”.

Another possibility is that all the digits have a different vowel (or vowel pair) from each other except “nine” and “five”. Changing “nine” to “niner” adds another vowel sound, which may help distinguish them when radio reception is poor.


"Niner" is spoken for the numeral 9 to avoid it being mistaken for 5.

  • 1
    $\begingroup$ This would be better as a comment once you gain enough reputation. $\endgroup$
    – dalearn
    Commented Jan 17, 2019 at 18:26
  • 7
    $\begingroup$ @dalearn, what is your basis for saying this would be better as a comment? It answers the question, and answers are frowned upon in comments. $\endgroup$ Commented Dec 14, 2021 at 3:06

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