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The international call for help used with voice radio transmission when an aircraft is in serious danger. Morse code uses an SOS in lieu. Mayday usually is transmitted on a guard frequency (121.5 MHz, 243 MHz, 406 MHz). The pilot is required to repeat the word Mayday thrice, followed by the call sign, the nature of the distress and his or her intentions, and the aircraft's position.
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved
international radiotelephone distress signal. [Maritime Hist.: Misc.]
Allusions—Cultural, Literary, Biblical, and Historical: A Thematic Dictionary. Copyright 2008 The Gale Group, Inc. All rights reserved.