Are international ATC and pilots technically required to learn British English, American English, or something else? I've heard it said that they are "supposed to speak ICAO standard phraseology, which just happens to be made up of English words," and that many ATC and pilots speak precisely as many English words as they need to scrape by. Even if they aren't explicitly required to speak AmE or BrE, they are still indirectly required to speak whichever version ICAO standard phraseology is based on, so if that is the case, which version would this be?

Some other things that I'm not asking about directly but might be helpful in providing a complete answer: a bit more about ICAO standard phraseology - is it considered a separate "controlled language" like Simplified Technical English, which was incidentally (or maybe not) developed for use in aviation maintenance manuals? Is it a subset of STE?

  • 6
    $\begingroup$ It isn't conversational English, so it really doesn't matter if you call it American or British. I would say it is a technical English or subset of English. Either way one who understands American English should be able to understand British English and vice-versa, since idioms and "turns of phrases" are not used. I don't need to know what a bonnet is (in reference to a car) or a Lorry, but I do know what queue means even though Americans don't typically say "queue" in reference to waiting in a line... $\endgroup$
    – Ron Beyer
    Jun 29, 2017 at 5:00
  • 1
    $\begingroup$ "Neither" is an answer, too, I guess. I'm really fishing for historical trivia rather than practical information, though. $\endgroup$
    – Matt
    Jun 29, 2017 at 5:11

3 Answers 3


The FAA bases English proficiency on the ICAO Level 4 English Language Proficiency Criteria, which don't mention any particular dialect or variant of English. Instead, they focus on the speaker's ability to communicate and they explicitly accept that the speaker may make mistakes (emphasis mine):

Pronunciation, stress, rhythm, and intonation are influenced by the applicant’s first language, but only sometimes interfere with ease of understanding.
Basic grammatical structures and sentence patterns are used creatively and are usually well controlled by the applicant. Errors may occur, particularly in unusual or unexpected circumstances, but rarely interfere with meaning.
There may be occasional loss of fluency [...] but this does not prevent effective communication

It's clear that ICAO doesn't expect non-native speakers to be fully fluent, and once you accept that then there's no benefit at all in trying to enforce a particular dialect. Using standard vocabulary and phrases is the real key to effective technical communication, and you can see that in many other professional contexts too.

I've met plenty of non-English speakers who can speak effectively but not fluently about a specific technical domain, but they still don't have the vocabulary to talk about their holiday plans or other 'trivial' topics. Asking what dialect of English those people speak is fairly meaningless, but Globish might be the best answer :-)



Declaring an emergency would be one of the most critical conversations, however it would be limited to something like this:

Pilot: MAYDAY, MAYDAY, MAYDAY, Metro Control, Big Jet 345, main electric failure, request immediate landing at Metro, position 35 miles north west of Metro, heading 120 flight level 80 descending, 150 persons on board, endurance three hours. ATC: Big Jet 345, Roger the MAYDAY, turn left heading 090, radar vectors ILS runway 27. Pilot: Big Jet 345 request runway 09. ATC: Big Jet 345, roger, turn right heading 140 for radar vectoring runway 09, descend to 3000 feet, QNH 995, report established. Pilot: Big Jet 345, heading 140, descend to 3000 feet QNH 995, report established localiser runway 09.

The vocabulary and the grammar used are very simple and the exchange takes advantage of the prescribed phraseology.

ICAO Chicago Convention, Annex 10. recommends using English and the local language. For both languages, local dialects are accepted as the norm. So for English there is indeed no reference to British or American, or any other variation.

Since 2003, ICAO recommends to member States to check for languages proficiency, setting the minimum acceptable level to 4. Actual and detailed requirements are found in Appendix 1 of Annex 1.

Annex 1, Appendix 1

Describes two types of criteria used to evaluate proficiency: An overall understanding, and explicit details.

  • To meet the language proficiency requirements contained in Chapter 1, Section 1.2.9, an applicant for a licence or a licence holder shall demonstrate, in a manner acceptable to the Licensing Authority, compliance with the holistic descriptors at Section 2 and with the ICAO Operational Level (Level 4) of the ICAO Language Proficiency Rating Scale in Attachment A.

Overall criteria allows for different dialects and accents:

  • 2. Holistic descriptors. Proficient speakers shall: [...] e) use a dialect or accent which is intelligible to the aeronautical community.

Detailed scale is found in Attachment A, ICAO language proficiency rating scale. I show here only levels 4 to 6, as 4 is the minimum expected for operational personnel.

enter image description here 1.1 Expert, extended and operational levels

ICAO member States have agreed on a set of standard phrases that must be used instead of plain language, plain language is used only when this phraseology is not effective. There is no requirement, for crew and controllers, to study the language like an interpreter would do, they just need to be understandable.

To understand the type of conversation used in regular communications:

Chicago Convention is used at national level by member States. When recommendations are not exactly followed, this is mentioned in the local AIP, section GEN 1.7 Differences from ICAO Standards, Recommended Practices and Procedures. AIPs links can be found on this Wikipedia page.

The next paragraphs just provide the references in ICAO documentation. You may skip them if not interested.

ICAO documents can be downloaded from the the Switzerland Federal Office of Civil Aviation, on this page (in French).

Annex 10

Standardized phraseology must be used before plain language.

  • ICAO standardized phraseology shall be used in all situations for which it has been specified. Only when standardized phraseology cannot serve an intended transmission, plain language shall be used. [...] Detailed language proficiency requirements appear in the Appendix to Annex 1.

Samples of ICAO standard phraseology found in Annex 10 (standard phrases are uppercase):

  • The following words and phrases shall be used in radiotelephony communications as appropriate and shall have the meaning ascribed hereunder: [...]

  • CONFIRM • “I request verification of: (clearance, instruction, action, information).”
  • CONTACT • “Establish communications with...”
  • CORRECT • “True” or “Accurate”.
  • CORRECTION • “An error has been made in this transmission (or message indicated). The correct version is...”
  • DISREGARD • “Ignore.”
  • HOW DO YOU READ • “What is the readability of my transmission?”
  • I SAY AGAIN • “I repeat for clarity or emphasis.”
  • MAINTAIN • “Continue in accordance with the condition(s) specified” or in its literal sense, e.g. “Maintain VFR”.
  • NEGATIVE • “No” or “Permission not granted” or “That is not correct” or “Not capable”.

For the crews, two languages are available.

  • The air-ground radiotelephony communications shall be conducted in the language normally used by the station on the ground or in the English language.

  • The English language shall be available, on request from any aircraft station, at all stations on the ground serving designated airports and routes used by international air services.

Pronunciation differences are taken into account, and there is a standardized pronunciation to be used for critical elements, like when spelling words and numbers, including when using English.

  • Word spelling in radiotelephony. [...] The pronunciation of the words in the alphabet as well as numbers may vary according to the language habits of the speakers. In order to eliminate wide variations in pronunciation, posters illustrating the desired pronunciation are available from ICAO.

  • When the language used for communication is English, numbers shall be transmitted using the following pronunciation [...]

Annex 1

In 2003 ICAO adjusted its Annex 1 to the Chicago Convention to add language proficiency requirements:

Amendment of definitions; new provisions requiring language proficiency for aeroplane and helicopter pilots, navigators using radiotelephony, air traffic controllers and aeronautical station operators; introduction of a Note on qualification and training for aeronautical meteorology personnel; amendment to the Human Factors knowledge requirements for Aircraft Maintenance Engineer.

This includes a requirement to demonstrate language proficiency, both for crews...

  • Aeroplane, airship, helicopter and powered-lift pilots and those flight navigators who are required to use the radio telephone aboard an aircraft shall demonstrate the ability to speak and understand the language used for radiotelephony communications.

and for ATCO.

  • Air traffic controllers and aeronautical station operators shall demonstrate the ability to speak and understand the language used for radiotelephony communications.

This proficiency has to be evaluated against a common scale.

  • As of 5 March 2008, aeroplane, airship, helicopter and powered-lift pilots, air traffic controllers and aeronautical station operators shall demonstrate the ability to speak and understand the language used for radiotelephony communications to the level specified in the language proficiency requirements in Appendix 1.

Those that don't match the highest level will be checked again and again...

  • Recommendation.— The language proficiency of aeroplane, airship, helicopter and powered-lift pilots, flight navigators required to use the radiotelephone aboard an aircraft, air traffic controllers and aeronautical station operators who demonstrate proficiency below the Expert Level (Level 6) should be formally evaluated at intervals.

But the natives and assimilated won't be bothered. They just need to show they are understandable by the international aeronautical community.

  • Formal evaluation is not required for applicants who demonstrate expert language proficiency, e.g. native and very proficient non-native speakers with a dialect or accent intelligible to the international aeronautical community.


There is actually a name for the subset of English that is used in aviation: Aviation English. However, it is not an official standard, but a name applied to the subset of English that is derived from the widely accepted ICAO recommendation to use English.

Note that Aviation English does not specify an accent (American or British or any other). The ICAO standard phraseology words have been specifically chosen to minimise confusion that might be caused by different accents.


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