COMDTINST 16121.1
JAN 29 1998
(3)
Sea Area A3: INMARSAT - Generally defined as the area between 70N and
70S. Sea Area A3 includes Sea Areas A1 and A2 if not declared effective by the
signatory nation.
(4)
Sea Area A4: Beyond Areas A1, A2, and A3. Generally defined as the regions
north of 70N and south of 70S.
5.
POLICY. Area and District Commanders shall promulgate specific procedures for processing
DSC communications within their Area of Responsibility.
a.
Guard Requirements.
(1)
Coast Guard Communications Stations will guard 6 DSC frequencies:
2187.5kHz, 4207.5kHz, 6312.0kHz, 8414.5kHz, 12577.0kHz, and 16804.5kHz
simultaneously.
(2)
Coast Guard Groups will guard 2187.5kHz and 156.525mHz (channel 70).
b.
DSC Distress alerts shall be acknowledged within 2.75 minutes (165 seconds) following
the initial distress alert.
c.
All DSC Distress calls will be acknowledged via DSC on the frequency the call was
received. All other DSC calls will be acknowledged if requested by the originator. The
originator will normally dictate the method of acknowledgment (i.e., DSC, voice, or
SITOR) and the working frequency in the initial DSC data transmission. If a specific
method of response (i.e., SITOR) is not available to the called station, it shall advise the
nearest equipped Coast Guard station to respond to the originator on its behalf.
d.
International Code of Signals, DMAHTC Pub 102, will be used whenever a language
barrier exists between the originating and responding stations.
e.
Radio checks via DSC are encouraged and accepted whenever possible. When
conducting radio checks via DSC, the alert signal shall not be used. Over-the-air testing
of DSC distress alerts is encouraged on the appropriate working frequency. Testing of
DSC distress alerts shall not be conducted on DSC guard frequencies.
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