Distress Communications

After any GMDSS equipment has been installed, the necessary operating instructions should be given to the appropriate personnel, specifically pointing out operating procedures for the equipment in question. It is important that operating instructions should be as clear and precise as possible in order that they are easy to understand.

Radio equipment used for transmitting distress alerts should be so designed that it should not be possible to transmit a distress alert unless the distress button is deliberately depressed. It is strongly recommended that personnel have full knowledge of the GMDSS and the consequences of transmitting a false alert. To reduce the chance of false alerts, routine testing of GMDSS equipment should only be undertaken under the direct supervision of the person responsible for communications.

To take maximum advantage of the GMDSS masters should ensure that all crewmembers that may be required to send a distress alert are instructed and knowledgeable in the operation of all relevant radio equipment on the vessel. Such instructions should also be given periodically on board the vessel to al relevant crewmembers by the person responsible for communications.

Unit 7 Worldwide Navigational Warning Service

The Worldwide Navigational Warning Service (WWNWS) established through joint efforts of the International Hydrographic Organization (IHO) and International Maritime Organization (IMO) is a coordinated global service for the promulgation of navigational warnings.

Navigational warnings are designed to give the mariner early information of important incidents which may constitute a danger to navigation. Many navigational warnings are of temporary nature, but others remain in force for several weeks and may be succeeded Notices to Mariners (NM).

Navigational warnings are of three types: NAVAREA warnings, Coastal warnings and Local warnings. The language in both NAVAREA and Coastal warnings is invariably English, although warnings may additionally be transmitted in one or more of the official languages of the United Nations.

Navarea warnings

For the purposes of the WWNWS the world is divided into 16 geographical sea areas termed NAVAREAS and identified by Roman numerals. The authority charged with collating and issuing long-range navigational warnings to cover the whole of an area is called the NAVAREA Coordinator. The type of information which might be contained in NAVAREA warnings includes failure of and changes to major navigational aids; newly discovered wrecks or natural hazards in or near main shipping lanes and areas where Search and Rescue (SAR), anti-pollution operations, cable-laying or other underwater activities are taking place.

NAVAREA warnings will normally be sufficient for a vessel passing through main shipping lanes clear of the coast.

Transmissions are arranged so as to fall within at least one normal radio watch period each day, and the information is repeated with varying frequency as time passes until either the danger has ceased or the information has been adequately promulgated elsewhere.