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
NATO phonetic alphabet underlined syllable of each letter word should be emphasized, and each syllable of the code words for the figures (1969–Present) should be equally emphasized. The Radiotelephony Spelling Alphabet is used by the International Civil Aviation Organization for international aircraft communications. The ITU-R Radiotelephony Alphabet is used by the International Maritime Organization for international marine communications. NATO phonetic alphabet The NATO phonetic alphabet, officially denoted as the International Radiotelephony Spelling Alphabet, and also commonly known as the ICAO phonetic alphabet, and in a variation also known officially as the ITU phonetic alphabet and figure code, is the most widely used radiotelephone