GMDSS
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Contents
Overview
- See also: GMDSS Modernization Plan
The Global Maritime Distress and Safety System (GMDSS) is an international system which uses improved terrestrial and satellite technology and ship-board radio systems. It ensures rapid alerting of shore-based rescue and communications authorities in the event of an emergency. In addition, the system alerts vessels in the immediate vicinity and provides improved means of locating survivors.
The GMDSS is mandatory for all cargo ships 300 gross tons or greater and all passenger vessels on international voyages.
GMDSS uses satellites and Digital Selective Calling (DSC) techniques on the MF, HF and VHF bands, enabling a distress alert to be transmitted and received automatically over both short and long distances.
Functional requirements for GMDSS
- Transmission of ship-to-shore distress alerts by at least two separate and independent means, using different radiocommunication service;
- Reception of shore-to-ship distress alerts;
- Transmission/reception of ship-to-ship distress alerts;
- Transmission/reception of search and rescue co-ordinating communications;
- Transmission/reception of on-scene communications;
- Transmission/reception of SART signals for locating;
- Transmission/reception of Maritime Safety Information;
- Transmission/reception of general radiocommunications to and from shore-based radio systems or networks; and
- Transmission/reception of bridge-to-bridge communications.
GMDSS Sea Areas
- A1 - Within VHF range of Coast Stations fitted with DSC (30-40 nm)
- A2 - Within MF range of Coast Stations fitted with DSC (150 nm)
- A3 - Within the area covered by Inmarsat Satellite System
- A4 - Polar Regions (above 70° N and below 70° S)
Carriage requirements
| GMDSS equipment carriage requirements | |||||
|---|---|---|---|---|---|
| Minimum requirements | VHF radio installation capable of transmitting DSC on channel 70, and radiotelephony on channels 16, 13 and 6; | ||||
| SART (2 over 500 GRT, 1 on 300 - 500 GRT) | |||||
| Two portable VHF transceivers for use in survival craft if under 500 GRT, three if over 500 GRT. | |||||
| NAVTEX receiver (if ship engaged on voyages in area where NAVTEX service is provided) | |||||
| Inmarsat EGC receiver (if ship engaged on voyages in any area of Inmarsat coverage where MSI services not provided by NAVTEX or HF NBDP) | |||||
| 406 MHz EPIRB (vessels trading exclusively in sea area A1 may carry a VHF DSC EPIRB in lieu of a 406 MHz EPIRB) | |||||
| Sea Area A1 - In addition to carrying the equipment listed in minimum requirements, every ship engaged on voyages exclusively in sea area A1 shall be provided with either of the following installations for the transmission of ship-shore Distress Alerts: | 406 MHz or VHF EPIRB (which may be the one specified in Minimum requirements) installed close to, or capable of remote activation from the position from which the ship is normally navigated | ||||
| ... OR ... MF DSC System (if ship is engaged on voyages within coverage of MF coast stations equipped with DSC) | |||||
| ... OR ... HF DSC System | |||||
| ... OR ... Inmarsat ship earth station (can be met by Inmarsat ship earth stations capable of two-way communications, such as Inmarsat-B, Fleet 77 or Inmarsat-C ship earth stations. Unless otherwise specified, this footnote applies to all requirements for an Inmarsat ship earth station prescribed by this chapter) | |||||
| Sea Areas A1 and A2 - In addition to carrying the minimum requirements, every ship engaged on voyages beyond sea area A1, but remaining within sea area A2, shall be provided with: | MF radio installation capable of transmitting and receiving, for distress and safety purposes, on the frequencies 2,187.5 kHz using DSC; 2,182 kHz using radiotelephony. | ||||
| DSC watchkeeping receiver operating on 2,187.5 kHz | |||||
Means of initiating the transmission of ship-to shore Distress Alerts by a radio service other than MF, either:
| |||||
| Sea Areas A1, A2 and A3 - In addition to carrying the equipment listed in minimum requirements, every ship engaged on voyages beyond sea areas A1 and A2, but remaining within sea area A3, shall be provided with: | Option 1:
Option 2:
AND
| ||||
| Sea Areas A1, A2, A3 and A4 - In addition to carrying the equipment listed previously, every ship engaged on voyages in all sea areas shall be provided with: | MF/HF radio installation | ||||
| MF/HF DSC watchkeeping receiver | |||||
| In addition, ships shall be capable of transmitting and receiving general radiocommunications using radiotelephony or direct-printing telegraphy by an MF/HF radio installation | |||||
Documents to be carried onboard
- Ship’s Radio License
- Radio Operators Certificates
- Safety Radio Certificate
- GMDSS Radio Log Book
- ITU List of Cell Signs and Numerical Identities of Stations used by Maritime Mobile and Maritime Mobile Satellite Services
- ITU List of Coast Stations
- ITU List of Ship Stations
- ITU List of Radio determination and Special Service Stations
- Antenna Rigging Plan
- Valid Shore Based Maintenance Certificate
Methods to ensure availability of GMDSS equipment at sea
Regulation 15 of the SOLAS GMDSS regulations defines 3 methods to ensure availability of GMDSS equipment at sea:
- At sea electronic maintenance, requiring the carriage of a qualified radio/electronic officer (holding a GMDSS First or Second class Radio-Electronics Certificate) and adequate spares and manuals;
- Duplication of certain equipment; or
- Shore based maintenance
Ships engaged on voyages in sea areas A1 and A2 are required to use at least one of the three maintenance methods outlined above, or a combination as may be approved by their administration.
Ships engaged on voyages in sea areas A3 and A4 are required to use at least two of the methods outlined above.
Most A3 GMDSS ships, along with nearly all A1 and A2 GMDSS ships do not opt for at sea maintenance - they either duplicate the equipment and use shore based maintenance (for A3 ships), or use shore based maintenance only (A1 and A2 ships).
Shore-based maintenance
The international requirements covering the Shore-Based Maintenance part of GMDSS are provided in SOLAS Chapter IV Regulation 15 “Maintenance Requirements”. IMO Resolution A.702(17) “Radio Maintenance Guidelines for the GMDSS” also applies for GMDSS equipment related to sea areas A3 and A4.
The equipment listed in the Declaration of Shore Based Maintenance (SBM) is covered by a corresponding agreement to provide its availability as required by SOLAS Regulation IV/15. A Shore Based Maintenance agreement / certificate is needed on board to fulfil the requirements.
It is the responsibility of national maritime administrations to ensure that companies offering SBM services are compliant with the above requirements.
Typically a country’s maritime administration will establish the specific national requirements for SBM service providers (which will be based on the international IMO requirements). The specific requirements to be met for a SBA service provider depend on the country/national administration in question.
