Morse code in Cayo Largo del Sur, Cuba is coded as "UCL", and UCL in Morse code is transmitted on its radio frequency. In some countries, during periods of maintenance, the facility may radiate a T-E-S-T code () or the code may be removed which tells pilots and navigators that the station is unreliable. In Canada, the identification is removed entirely to signify the navigation aid is not to be used. In the aviation service, Morse is typically sent at a very slow speed of about 5 words per minute. In the U.S., pilots do not actually have to know Morse to
Morse code abbreviations sentences and questions in short three character codes each beginning with the character Q. For example, the code word QTH means "My location is". If this code word is followed by a question mark as QTH? it means "What is your location?". Typically very few full words will be spelled out in Morse code conversations. Often vowels are left out to shorten transmissions and turn overs. Other examples, of internationally recognized usages of Morse code abbreviations and well known code numbers, such as those of the Phillips Code from past eras of telegraph technology, are usages such as WX for