What are “Q” codes

The Q code is a standardized collection of three-letter message encoding all of which start with the letter “Q”, initially developed for commercial radotelegraph communication. Q codes were created when radio used Morse code exclusively, they continued to be employed after the introduction of voice transmissions. To avoid confusion, transmitter call signs are restricted; while an embedded three-letter Q sequence may occur no country is ever issued an ITU prefix starting with “Q”. The codes in the range QAA–QNZ are reserved for aeronautical use; QOA–QQZ for maritime use and QRA–QUZ for all services.