Aeronautical Radiotelephony Communications
The sole object of ICAO language proficiency requirements is aeronautical radiotelephony communications, a specialized subcategory of aviation language corresponding to a limited portion of the language uses of only two aviation professions — controllers and flight crews. It includes ICAO standardized phraseology and the use of plain language. The standardized words and phrases of ICAO phraseology approved for radiotelephony communications have been developed over years and represent a true sub-language as defined above. It may be useful to consider aviation language, radiotelephony language, and phraseologies as increasingly smaller subsets within the larger category of “language”