There Is No Place for Idiomatic Language in Aviation… Or Is There?

Nikki Jane Author

There Is No Place for Idiomatic Language in Aviation… Or Is There? A Look at ICAO English Proficiency

In aviation, clarity, precision, and brevity are not just ideals; they are operational necessities. Radiotelephony phraseology exists precisely to eliminate ambiguity, reduce workload, and ensure that meaning is transmitted instantly and accurately across languages and cultures. Against this backdrop, the idea of idiomatic language can seem, at best, unnecessary and, at worst, risky.

And yet, the ICAO Language Proficiency Requirements (LPRs) explicitly include idiomatic language as a feature of higher-level proficiency.

What the ICAO LPR Scale Says About Idiomatic Language (Levels 4, 5, and 6)

The ICAO rating scale does not ignore idiomatic language; it incorporates it as a marker of advanced proficiency, particularly at Levels 5 and 6.

At Level 4 (Operational), there is no mention of idiomatic language.

At Level 5 (Extended), the vocabulary descriptor states:

“Vocabulary range and accuracy are sufficient to communicate effectively on common, concrete, and work-related topics. Paraphrases consistently and successfully. Vocabulary is sometimes idiomatic.”

At Level 6 (Expert), this develops further:

“Vocabulary range and accuracy are sufficient to communicate effectively on a wide variety of familiar and unfamiliar topics. Vocabulary is idiomatic, nuanced, and sensitive to register.”

These descriptors make two things clear. First, idiomatic language is associated with higher proficiency. Second, it is not framed as essential, but as an indicator of linguistic richness and flexibility.

ICAO Document 9835 (Manual on the Implementation of ICAO Language Proficiency Requirements) reinforces this perspective. It emphasises that plain language, used when phraseology is insufficient, is a critical component of safe communication. Within that plain language, natural language features, including idiomatic usage, may appear, particularly among highly proficient and native speakers.

Idiomatic Language in Aviation: Safety Concerns and Common Objections

Despite this, many aviation professionals argue that idiomatic language has no place in aviation communication, and should not be included in the ICAO Language Proficiency Rating scale.

The reasoning is understandable:

• Idioms can be ambiguous
• They often rely on cultural knowledge
• They may confuse non-native speakers
• They can conflict with the principles of clarity and brevity

If a pilot says, “We’ll play it by ear” (we will decide what to do as the situation develops), or “That came out of the blue” (it was completely unexpected), the meaning may not be immediately clear to an international listener.

From this perspective, idiomatic language seems not just unnecessary, but potentially hazardous.

And in one sense, this criticism is valid - particularly when, as is often the case, we associate idiomatic language with idiomatic expressions.

However, …

Idiomatic Language Is More Than Just Idioms

When many people hear “idiomatic language,” they immediately think of fixed idiomatic expressions such as:

• “Kick the bucket” (to die)
• “Call it a day” (to stop working on a project or task)
• “Cost an arm and a leg” (expensive)

These are indeed idiomatic, but they represent only a narrow slice of what idiomatic language actually is.

In linguistic terms, idiomatic language refers more broadly to language where meaning is not strictly literal, or where usage reflects natural, conventional patterns of a language.

This includes similes, metaphors, hyperbole, phrasal verbs, and other forms of non-literal language.

Similes and Metaphors in Aviation English

Similes and metaphors are not typically part of standard phraseology, but they do appear in real-world aviation communication, especially outside strictly controlled RT exchanges.

Examples of similes (comparisons using “like” or “as”):

• “The landing was like butter” (very soft and smooth)
• “The workload went up like crazy” (increased very quickly and significantly)
• “The approach was as steady as a rock” (very stable, no deviations)

Examples of metaphors (direct comparisons without “like” or “as”):

• “We were flying blind for a few seconds” (we temporarily lacked reliable visual or instrument information)
• “This sector is a bottleneck right now” (traffic congestion causing delays)
• “We’ve got a window to get in” (limited opportunity in time or conditions)
• “They were behind the aircraft” (not keeping up with workload or situation)

These expressions are often understandable because they rely on shared imagery. However, they are not essential and would not be appropriate in critical or safety-sensitive transmissions.

Hyperbole in Aviation Communication

Hyperbole (deliberate exaggeration) is another form of idiomatic language that can appear in aviation contexts, particularly in informal communication.

Examples include:

• “There’s a ton of traffic waiting to come in” (a lot of traffic)
• “We were waiting forever for clearance” (a long time)
• “That was the longest final ever” (a very long final approach)
• “That delay lasted ages” (a very long time)

While these expressions add emphasis, they reduce precision. In operational communication, more exact language is always preferred.

Phrasal Verbs in Aviation English

Perhaps the most important, and often the most hated, category of idiomatic language is the phrasal verb.

Many phrasal verbs are idiomatic because their meaning cannot be fully inferred from the individual words. Yet they are deeply embedded in aviation English, including standard phraseology.

Examples include:

• “Line up and wait” (enter the runway and be ready for departure)
• “Take off” (begin flight from the ground)
• “Climb out” (continue climbing after departure)
• “Level off” (stop climbing or descending and maintain altitude)
• “Shut down” (turn off the engines)

These are idiomatic constructions, yet they are essential to aviation communication.

Idiomatic Language vs. Operational Communication

The key to resolving this apparent contradiction lies in context.

Aviation communication operates across two overlapping domains:

• Standardised phraseology, which prioritises clarity, brevity, and predictability
• Plain language, which is used when phraseology is insufficient

Idiomatic expressions like “kick the bucket” clearly have no place in either domain. They are culturally specific and potentially confusing.

However, other forms of idiomatic language, especially those that are widely understood or conventionalised, can function effectively within plain language, particularly at higher levels of proficiency.

In my view, ICAO does not require pilots or controllers to use idiomatic language. Rather, it recognises that those at Level 5 and especially Level 6 can:

• Understand idiomatic usage
• Use it appropriately when context allows
• Adjust their language to suit the communicative situation

True proficiency is not necessarily about using more complex language; it is about using the right language at the right time.

So, is there a place for idiomatic language in aviation?  My two cents:

Yes. And no.

• In standard phraseology, the answer is clearly no (with the exception of certain phrasal verbs)
• In plain language, the answer is: sometimes, and with care
• In language assessment, the answer is yes, as an indicator of higher proficiency

Idiomatic language, in its broader sense, reflects a speaker’s ability to operate naturally and flexibly in English. But aviation communication demands discipline, awareness, and adaptability.

Implications for the ICAO English Language Proficiency Test (ELP)

Candidates preparing for ICAO English tests should understand that:

• They are not required to produce idiomatic expressions to achieve a high score
• At higher levels, they may demonstrate natural and appropriate usage, always maintaining clarity

Importantly, the ICAO descriptors do not imply that pilots or controllers should actively seek to use idiomatic language. Rather, they recognise that highly proficient speakers can both understand and, where appropriate, use such language without compromising clarity.

For raters, idiomatic language should be seen as one feature among many, not a requirement, but evidence of linguistic depth when used appropriately.

More Information / Book Your ICAO ELP Test

If you would like to learn more about ICAO English Language Proficiency requirements, or if you are ready to book an official ELP test for pilots or air traffic controllers, feel free to contact us. We will be happy to support you with reliable testing and expert guidance.