RADIO AIDS TO MARINE NAVIGATION - Canadian Coast Guard

The radiotelephone distress frequencies are:
i) 2182 kHz on medium frequency (MF) band; and
ii) 156.8 MHz (ch 16) on very high frequency band (VHF); and
iii) any other available frequency on which attention might be attracted if transmissions on 2182 kHz and 156.8 MHz are
not possible or successful.
The digital selective calling (DSC) frequencies are:
i) Channel 70 in the VHF band;
ii) 4207.5 kHz;
iii) 6312.0 kHz;
iv) 8414.5 kHz;
v) 12577 kHz; and
vi) 16804.5 kHz in the High Frequency (HF) bands.
When another craft or person is in distress:
i) all transmissions capable of interfering with the distress traffic must be stopped;
ii) attention must be concentrated on the distress communications and all information possible intercepted; and
iii) a station in the vicinity of the distressed craft must acknowledge receipt of the distress message if received, giving its
own position in relation to that of the craft in distress and stating the action being taken.
Distress communications consist of the:
• Distress Signal;
• Distress Call;
• Distress Message; and
• Distress Traffic.
Transmission of a Distress Signal and/or a Distress Call announces that the ship, aircraft, other vehicle, or person that is
making the transmission is:
i) threatened by serious and imminent danger and requires immediate assistance; or
ii) aware of another ship, aircraft, other vehicle or person is threatened by serious and imminent danger and requires
immediate assistance; and
iii) distress communications should be repeated by the craft in distress until an answer is heard.
The Alarm Signal
The radiotelephone Alarm Signal consists of the continuous alternate transmission of two audio tones of different pitch for
a period of at least thirty seconds but not to exceed one minute. The sound of this tone is similar to that used by some
ambulances.
The Alarm Signal is used by Canadian MCTS Centres to alert ships:
i) that a mayday relay broadcast is about to follow; or
ii) that a Tsunami warning, which should be preceded by the Urgency Signal (PAN PAN) is about to follow; or,
iii) that the transmission of an urgent cyclone warning, which should be preceded by the Safety Signal (SÉCURITÉ), is
about to follow.
The Alarm Signal transmitted by the coast radio station will normally be sent for a period not exceeding thirty (30) seconds
and will be followed by a ten (10) second continuous tone.
The Distress Signal consists of the word “MAYDAY”.
The Distress Call consists of:
i) the word “MAYDAY” (spoken three times)
ii) the words “This is” followed by
iii) the name of the ship in distress (spoken three times) and
iv) the ship’s MMSI number (if a DSC distress alert has been sent).
The Distress Call:
i) should not be addressed to a particular coast radio station or ship; and
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