Q codes

A set of codes created in the early 20th century by the British government to facilitate communications between its warships and coastal stations. This system was initially developed for radiotelegraphy, but gradually extended to different fields, including radio communications in aviation. Each of the Q codes consists of three letters. The first is the identifier and in all codes it is the Q. Those assigned to aviation are those included in the QAA-QNZ range, and among them are several that provide the pilot with different atmospheric pressure references.