Aviation English Pronunciation

As anyone who has studied or worked with the ICAO Language Proficiency Requirements (LPRs) will know, the Pronunciation level descriptors are less than perfect at distinguishing between the different levels.

For example, between Levels 4 and 5 we see the only substantial difference is that the features of pronunciation “rarely” interfere with ease of understanding as opposed to “only sometimes” doing so.

This raises a number of questions:

  1.  How can we reliably determine whether the interference happens “rarely” or “sometimes” in a way that is fair to test takers?
  2. Whose ease of understanding are we talking about? Ours, or some hypothetical third party?

One of the key elements of rater training when helping people to become assessors of the ICAO LPRs is giving them tools that they can use to apply in order to award fair ratings. Indeed, a whole module of our rater course is devoted to this.

Pronunciation LPRs

ICAO Language Proficiency Requirements for Pronunciation

But how important is pronunciation, anyway?

Research seems to suggest it’s very important, and is often cited as a cause of miscommunication over the radio – more often than other ICAO LPRs – by professionals in the field (e.g. Tiewtrakul & Fletcher 2010; Kim & Billington 2018).

Whether or not that is because Pronunciation is simply a more salient feature of someone’s language in a short utterance, it underscores the importance of speakers speaking in a way that is easy to understand over the radio.

L1-influenced pronunciation is one of the critical factors in international communication contexts where English spoken as a lingua franca”

Kim & Billington (2018)

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As ICAO themselves note in Document 9835, Comprehension is only one of six language proficiency requirements, but represents 50% of the linguistic task, and Comprehension greatly depends on the Pronunciation of the speaker (Tiewtrakul & Fletcher, 2010). Pronunciation and Comprehension are two sides of the same coin when it comes to effective communication, especially where communication is entirely verbal, without recourse to other, visual, cues. As Kim and Billington (2018, p.132) note: “L1-influenced pronunciation is one of the critical factors in international communication contexts where English spoken as a lingua franca”.

Lingua Franca

For a long time we at Lenguax have found the work done by Jenkins (2006) and others on the notion of “English as a Lingua Franca” to be useful in this context.

To summarise her findings briefly, several aspects of English pronunciation are more important than others when two non-native speakers of English are using English as a means of communication.

These features include:

  • all of the consonant inventory of English, with the exception of the “th” sounds, which do not seem to be particularly important for understanding.
  • the long-short vowel distinction, including the fortis-lenis distinction in a vowel when the next consonant is voiced or unvoiced (e.g. the difference in vowel length between the vowel in “ice” as opposed to in “eyes”).
  • word-initial consonant clusters.
  • appropriate use of stress.

These, at least, give us a starting point for both rating and for teaching: are our students able to produce the full consonant inventory of English?

Many students in contexts where we have taught, such as China and the Gulf, have found some of these distinctions troublesome, which leads in no small part to their difficulties in being understood internationally.

ELF Not Enough?

But as authors such as Kim and Billington point out, these findings were from situations such as classrooms which afforded all manner of advantages that speakers on the radio do not enjoy, such as visual cues and extended interactions with the interlocutor.

Kim and Billington identify some potential confusions in the audio samples they analysed for their study which were not consistent with Jenkins’ findings, such as confusions arising from dropped or mispronounced word-final consonants or consonant clusters (e.g. “hold” sounding as “hon” from one Korean controller), and a vowel substitution in the word “taxi” (sounding as /teksi/).

Kim and Billington recommend that learners become more aware of the aspects of their pronunciation that may impact the way they produce sounds in English. This in turn suggests that their teachers need to be aware of this, which in our experience is not always the case.

Here at Lenguax we believe that good Pronunciation teaching is important, which is why we dedicate some significant time to it on our online course for teachers.

We believe that  greater familiarity with the work of Jenkins, and others, and practical methods of teaching towards some of their findings, that the state of Pronunciation teaching in Aviation English contexts can only be improved. 

We also believe, like Kim (2023) that much greater exposure to international varieties of English in practice situations will be beneficial: let pilots and ATCs listen to examples of speakers from different regions of the world, with different pronunciation, with pedagogical input to help them understand the differences in pronunciation. Greater familiarity with other ways of speaking leads to fewer misunderstandings.

Therefore, our next project is intended to be a suite of listening materials aimed at pilots and ATCs which will show them what to expect from listening to the pronunciations of different nationalities.

It is to be hoped that such a resource can help pilots and controllers with their own comprehension of international accents, while also providing teachers with some insights into the difficulties speakers face to inform their own pronunciation teaching.

If you are interested in this project, to learn more or perhaps to lend your voice, please get in touch using the form below.


Jenkins,J. (2006). Current perspectives on teaching World Englishes and English as a lingua franca. Tesol Quarterly, 40, 157–181.

Kim, H & Billington, R. (2018). Pronunciation and comprehension in English as a lingua franca communication: Effect of L1 influence in international aviation communication. Applied Linguistics, 39/2, 135-158.

Kim, Y. (2023). The challenges of radiotelephony communication and effective training approaches: A study of Korean pilots and air traffic controllers. English for Specific Purposes, 72, 26-39.

Tiewtrakul, T & Fletcher, S. (2010). The challenge of regional accents for aviation English language proficiency standards: A study of difficulties in understanding in air traffic control-pilot communications. Ergonomics, 53:3, 229-239.

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