“I speak English fluently in everyday life. Why did I get Level 4?” The answer involves more than how smoothly you speak. ICAO language assessment considers pronunciation, structure, vocabulary, fluency, comprehension and interactions separately. The lowest rating determines the overall level. See the rating scale and explanation published by EUROCONTROL ELPAC.

Levels 4, 5 and 6 are called Operational, Extended and Expert. One way to understand the progression is that language performance becomes more consistent across a broader range of topics and communication demands. That is a reading aid, not a replacement for the six descriptors—and certainly not a way to assign a rating from a short self-introduction.

An accent does not mean a low rating

The pronunciation criterion concerns ease of understanding, not where the speaker comes from. Across Levels 4, 5 and 6, the descriptors distinguish between pronunciation features that sometimes, rarely or almost never make understanding harder. Even the Level 6 descriptor allows for first-language or regional influence. See the full scale on the ELPAC website.

An identifiable Thai accent is therefore not, by itself, a reason for a low rating. Sounding British or American does not establish that all six criteria have been met either. A recognisable accent and pronunciation that obstructs understanding are different things. Confusing them can turn improvement into an attempt to imitate a particular identity, without addressing what actually makes a message difficult to understand.

Level 5 does not require error-free grammar

For structure, Level 4 calls for basic patterns to be generally well controlled. At Level 5, control of basic structures is consistent, while attempts at complex structures can still contain errors that sometimes affect meaning. Level 6 calls for consistent control of both basic and complex structures. These distinctions appear in the ICAO scale reproduced by ELPAC.

This does not mean that Level 5 is more forgiving of errors than Level 4. The descriptions address different ranges of language: one focuses on basic structures, while the other also addresses complex expression. Comparing the frequency of errors without those qualifications gives a misleading picture.

Nor does it follow that longer sentences earn a higher rating. Sentence length is not a separate criterion. Making a message harder to follow in an effort to demonstrate complex grammar is not the same as controlling that grammar. When reading feedback, distinguish recurring problems with basic structures from difficulties with more complex expression, rather than simply counting mistakes.

Fluency is not speed or a well-rehearsed speech

The fluency descriptors progress from an appropriate pace with acceptable hesitation in spontaneous exchanges at Level 4, to sustained discussion of familiar topics with relative ease at Level 5, and then to natural, flexible speech at Level 6. The full descriptors provide the qualifications behind that summary.

A polished introduction delivered quickly shows how smoothly that particular introduction can be delivered. It does not establish what happens when the question changes. Equally, one brief pause cannot determine a rating on its own. Its position, effect on communication and place within the wider performance matter more than an ambition to eliminate every pause.

This can help explain a gap between confidence in everyday conversation and an assessment result. Familiar listeners know your background and may fill in what you leave unsaid. Familiar topics can also let you avoid language you find difficult. An assessment needs evidence beyond those favourable conditions.

Understanding routine content is not the whole picture

The ICAO licensing FAQ reproduces the Level 4 descriptor allowing slower understanding or clarification when communication becomes complicated or unexpected. The Level 5 discussion in Doc 9835, printed page 4-13, describes accurate understanding of common work-related topics and mostly accurate understanding when complications arise. Level 6 extends to a wider range of contexts and subtleties, as shown in the rating scale.

These descriptions do not support a rule that asking for repetition once rules out a higher rating. More useful questions are why clarification was needed, whether it resolved the difficulty, and how such difficulties affected the overall exchange. Safe communication should not involve concealing uncertainty to appear fluent.

Vocabulary and interaction also need attention. Knowing a technical term is different from being able to explain what you mean. Speaking continuously is different from responding to the other person's question. Judging English solely by how smoothly someone talks leaves listening and the shared work of communication out of the picture.

Stronger skills cannot raise an average

Suppose the six ratings are 5, 5, 5, 5, 4 and 5. The overall result remains Level 4 under the lowest-rating rule. This hypothetical example does not mean the five stronger ratings have no value. It means the overall result represents the level reached across all six criteria.

After receiving Level 4, the useful question is therefore which criterion determined the result—not whether every aspect of your English is “only Level 4”. Where individual ratings and comments are available, consider them together. Neither this article nor a written answer can establish the level an individual should receive.

Level 6 does not give you licence to improvise phraseology

ICAO explicitly states that language proficiency requirements do not reduce the requirement to use standard phraseology. Use the specified phraseology where it applies, and plain language when it cannot convey the intended message. See the ICAO FAQ on standardised phraseology.

A higher rating should not be interpreted as permission to use more slang on frequency, make transmissions unnecessarily complex or omit necessary confirmation. Language ratings and operational procedures serve different purposes; one does not replace the other.

Making sense of your own rating

The useful outcome of comparing these levels is not to label yourself “basic”, “fluent” or “native”. It is to replace a vague judgement with more specific questions: whether listeners struggle to understand you, whether basic grammar remains stable, whether you can communicate beyond familiar topics, and whether you follow changes in what you hear.

This article explains the standard; it does not diagnose an individual's proficiency. A formal result must come from the applicable assessment process, and licensing requirements and recognition of results remain matters for the relevant authority. Understanding the descriptors can help you interpret a result, but it cannot replace an assessment or establish operational qualifications.

Sources and reading notes

Last reviewed: September 30, 2026. This is an independent ATCBase explanation, not official ICAO wording. It focuses on commonly misunderstood differences rather than reproducing the complete rating scale.