Since 1998 the aviation community, fostered by the International Civil Aviation Organization (ICAO), has been undergoing a global standardization process concerning language use in international communications. English has gradually become the official language of aviation. Major difficulties with this highly specialized and constrained language, also known as Aviation English or Airspeak, put air-ground communications at severe risk. In case of danger, standardized phraseologies, i.e. regulated pronunciation of numbers, acronyms, abbreviations, and a finite number of possible messages structured in a concise and unambiguous way, are fundamental, however not sufficient. Previous research have highlighted that real ATC messages diverge from ICAO standards. In this regard, the present investigation is twofold. Firstly, it aims to verify if ATC messages included in two chosen corpora, namely Air Traffic Control Simulation Speech Corpus (ATCOSIM) and Air Traffic Control (ATC) Corpus confirm previous research results or if their structure fulfills ICAO standards. To carry out the analysis, a list of lexico-grammatical and pragmatic features typical of everyday conversations, and, thus, which should not occur in air-ground transmissions are identified by referring to ICAO Manual of Radiotelephony (2007) and Procedures for Air Navigation Services – Air Traffic Management (PANS-ATM) 4444 (2007) and then compared among the corpora. Results show that real ATC utterances are not compliant with standards in many respects. Possible motivations for their employment are, therefore, determined. In the second part of this paper a learner speech corpus of Aviation English is proposed. Taking ATCOSIM and ICLE corpora as a reference, a set of design criteria are discussed and a tentative description of the would-be corpus is provided.