International distress frequency

An international distress frequency is a radio frequency that is designated for emergency communication by international agreement.

History

For much of the 20th century, 500 kHz was the primary international distress frequency. Its use has been phased out in favor of the Global Maritime Distress Safety System.

Use of some distress frequencies is permitted for calling other stations to establish contact, whereupon the stations move to another frequency. Such channels are known as distress, safety and calling frequencies.^[1]

Satellite processing from all 121.5 or 243 MHz locators has been discontinued. Since February 1, 2009, the U.S. Coast Guard only monitors distress signals from emergency position indicating radio beacons that broadcast using digital 406 MHz signals.^[2] Digital 406 MHz models became the only ones approved for use in both commercial and recreational watercraft worldwide on January 1, 2007.^[3]

Current frequencies

International distress frequencies, currently in use are :

• 500 kHz is still monitored but as of 2010 has ceased to be used as the primary distress calling frequency at sea

• 2182 kHz for medium range maritime voice use. The US Coast Guard has said "beginning August 1st, 2013 the Coast Guard would no longer monitor 2182 kHz",^[4] as have many other coast guard services.

• Several HF maritime voice frequencies exist for long-distance distress calls:
  • 4.125 MHz^[5]
  • 6.215 MHz^[5]
  • 8.291 MHz^[5]
  • 12.290 MHz^[5]
  • 16.420 MHz^[5]

• 121.5 MHz is the civilian aircraft emergency frequency or International Air Distress frequency. It is used by civilian distress radiobeacons; however, the Cospas-Sarsat system no longer monitors the frequency.

• 243 MHz for NATO military aircraft emergency frequencies

• Marine VHF radio Channel 16 (156.8 MHz) for short range maritime use

• 406 MHz to 406.1 MHz is used by the Cospas-Sarsat international satellite-based search and rescue (SAR) distress alert detection and information distribution system

Digital Selective Calling frequencies

Several maritime frequencies are used for Digital Selective Calling (DSC), and they are also monitored for DSC distress signals:

• 2.1875 MHz^[5]
• 4.2075 MHz^[5]
• 6.312 MHz^[5]
• 8.4145 MHz^[5]
• 12.577 MHz^[5]
• 16.8045 MHz^[5]
• 156.525 MHz Marine VHF radio Channel 70

Amateur radio frequencies

• Emergency Centre of Activity (ECOA) frequencies informally established by the International Amateur Radio Union regional organizations (frequencies shown in kHz):

• Emergency/Disaster Relief Interoperation Voice Channels of the amateur radio Global ALE High Frequency Network:
  • 3791.0 kHz USB^[9]
  • 7185.5 kHz USB^[10]
  • 10145.5 kHz USB^[11]
  • 14346.0 kHz USB^[12]
  • 18117.5 kHz USB^[13]
  • 21432.5 kHz USB^[14]
  • 24932.0 kHz USB^[15]
  • 28312.5 kHz USB^[16]

• CB radio (citizens band)
  • Emergency channels 9 (27.065 MHz AM) and 19 (27.185 MHz AM)

See also

• Distress signal
• Global Maritime Distress Safety System
• Mayday
• SOS

References