What is Mayday ( distress) Relays?

Stations not themselves in distress which learn that a ship, aircraft or other vehicle is in distress may transmit a distress relay message but only in the following circumstances.

1. When the station in distress in not itself in position to transmit the distress message.
2. When the master or other person responsible for the station not in distress consider the further help is required/ necessary.
3. When, although not in position to render assistance, the station has received a distress message which is believed not to have been acknowledge.

Such message/ distress relay would normally be sent on 2182 kHz or channel 16 or any other R/T distress frequency.