Pilots and air traffic controllers need to undergo a specific English test in order to be granted a license for international operations. A language proficiency scale was developed to serve as a parameter to all aviation regulatory agencies throughout the world by targeting the language produced specifically by air traffic controllers and pilots in radio communications when non-routine situations (such as technical problems, bird strike, changes in weather, health problems on board, etc.) occur (ICAO 2010). However, there is a lack of empirical investigation which could shed light upon this particular register helping the users of the scale with its understanding. In an attempt to fill this gap, this paper outlines a compilation of the Radiotelephony Plain English Corpus (RPTEC), a spoken corpus of aeronautical communication consisting of transcriptions of exchanges between pilots and air traffic controllers in non-routine situations for research and pedagogical purposes. By presenting steps taken during the process, we intend to provide fellow researchers with data which may suit other purposes and yield further analyses, as well as enlighten similar investigations in the field of English for Specific Purposes.