In this chapter, we present a linguistic description of Aviation English (AE), from the level of pragmatics and discourse to that of phonology and intonation. As noted by Feak (2013), AE is a spoken variety of English, with no written version except for the phrases documented in the regulations describing it, for instance the ICAO manuals and the legislation for each individual country (the Aeronautical Information Publications, or AIP), or in teaching materials (Lopez, 2013). A restricted version of AE is used with controller-pilot data link communication (CPDLC) technology, which allows air-ground text messages on a computer screen but, as messages transmitted via CPDLC are selected from a menu, rather than typed, they will not be considered here.