The Morse Code was originally used for Radio Telegraphy, but nowadays it has been replaced by voice communications in Radio Telephony. But, navigational aids like NDB’s and VORs still send out their identifying letters by means of the Morse Code. Therefore, pilots must be able to listen to the identification in Morse to decide whether or not his navigational radios are tuned to and receiving the correct station. Pilots do not have to learn Morse code by heart, but they need to identify a repeated three-letter Morse code within a reasonable short time with the aid of the Morse code table below:
