The International Civil Aviation Organization (ICAO) has assigned levels to various degrees of Aviation English fluency.
There are 6 levels of language proficiency for air traffic communication:
- Operational (minimum required proficiency)
To operate an aircraft, one must achieve a minimum level of 4.
The Critical Boundary of Level 4:
- Slight issues with word definitions, being able to paraphrase, contain the appropriate pace of delivery, non-distraction fillers, and being able to check and request clarification