The International Civil Aviation Association has developed a set of Language Proficiency Requirements (LPRs) and a Language Proficiency Rating Scale, which seeks to define proficiency in the language needed for aviation purposes at six different levels. Pilots, air traffic controllers and aeronautical station operators are required to achieve at least Level 4 on this scale (usually in English, the de facto language of international aviation) in order to be licensed to fly aircraft or control air traffic on international (cross-border) flights or to work in international operations. This article summarises a series of research studies into the implementation of the LPRs and speculates on the reasons for the current state of affairs, with particular emphasis on the macro- and micropolitics of individuals and organisations. (Contains 1 table.)