■ Basic concept of GMDSS

Prior to the introduction of the GMDSS, maritime distress and safety communication relied primarily on the
capability of a ship in distress to alert another ship for assistance. The GMDSS emphasises authorities ashore
as well as shipping in the vicinity in order to achieve a rapid coordinated response to distress situations.
The shore-based rescue authorities now have the primarily role of coordinating assistance and rescue operation
following a distress alert. In the past, assistance was possible only if ships capable of receiving the distress call
were within radio range. The danger was that calls for assistance would go unheard in remote areas
In the GMDSS, the initial acknowledgement of a distress alert should be by the shore- based authorities.
Subsequent actions and communications should be controlled by the assigned Rescue Coordination Center(RCC).
In normal circumstances it should not be necessary for a ship to relay a distress alert. In order to avoid confusion
and delay, ships must monitor the RCC to be certain that the original alert was not received before initiating
a distress relay.
Particular care is needed when a distress call is received on HF at a considerable distance from the incident to
avoid making unnecessary or confusing transmissions in response.
The method of distress alerting can depend on the sea area in which the ship the ship is sailing and on the
equipment carried.