Distress frequencies. For the purposes of safety and distress there are certain frequencies that have been specially reserved for their exclusive use internationally. They are the following:

1. Medium frequency (MF) 518 kHz.
   Used by coast radio stations to transmit meteorological and navigation warnings and urgent information to ships using the international NAVTEX system of narrow band direct printing.
2. High frequency (HF) 2182 kHz.
   Used for radio telephony (voice) distress calls and messages.
3. Very high frequency (VHF) 121.5 MHz.
   Used for aeronautical distress calls and messages (voice). It is also used for survival craft and equipment .
4. Very high frequency (VHF) 156.8 MHz.
   Used for maritime distress calls and messages (voice). It is also used for survival craft and equipment. Commonly referred to as “Channel 16”.
5. Ultra high frequency (UHF) 243 MHz.
   Used for aeronautical distress calls and messages (voice). It is also used for survival craft and equipment.
6. Ultra high frequency (UHF) 406 MHz.
   Used for emergency position indicating radio beacon (EPIRB) earth to satellite links.

Silence periods. For three minutes past the hour and three minutes past the half hour, all ships fitted with the distress radio frequency bands are to set watch for distress traffic on 2182 kHz (voice). During this time all other transmission should cease.