Global Maritime Distress Safety System
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2008-07-03T16:38:09Z
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The '''Global Maritime Distress Safety System''' ('''GMDSS''') is an internationally agreed-upon set of [[safety]] procedures, types of equipment, and communication protocols used to increase safety and make it easier to [[rescue]] [[distress]]ed [[ship]]s, [[boat]]s and [[aircraft]].
GMDSS consists of several systems, some of which are new, but many of which have been in operation for many years. The system is intended to perform the following functions: alerting (including position determination of the unit in distress), [[search and rescue]] coordination, locating (homing), maritime safety information broadcasts, general communications, and bridge-to-bridge communications. Specific radio carriage requirements depend upon the ship's area of operation, rather than its [[tonnage]]. The system also provides redundant means of distress alerting, and emergency sources of power.
Recreational vessels do not need to comply with GMDSS radio carriage requirements, but will increasingly use the [[#Digital Selective Calling|Digital Selective Calling]] (DSC) VHF radios and offshore vessels may elect to equip themselves further. Vessels under 300 [[Gross tonnage]] (GT) are not subject to GMDSS requirements and vessels from 300 to 500 GT have less restrictive carriage requirements than vessels 500 GT and over.
==Components of GMDSS==
The main types of equipment used in GMDSS are:
===Emergency Position-Indicating Radio Beacon (EPIRB)===
{{main|Emergency Position-Indicating Radio Beacon}}
[[Cospas-Sarsat]] is an international [[satellite]]-based search and rescue system, established by Canada, France, the United States, and Russia. These four countries jointly helped develop the 406 MHz [[Emergency Position-Indicating Radio Beacon]] (EPIRB), an element of the GMDSS designed to operate with Cospas-Sarsat system. These automatic-activating EPIRBs, now required on [[International Convention for the Safety of Life at Sea|SOLAS]] ships, commercial fishing vessels, and all passenger ships, are designed to transmit to a rescue coordination center a vessel identification and an accurate location of the vessel from anywhere in the world. Newest designs incorporate [[Global Positioning System|GPS]] receivers to transmit highly accurate positions of distress.
===NAVTEX===
{{main|Navtex}}
[[Navtex]] is an international, automated system for instantly distributing maritime navigational warnings, weather forecasts and warnings, search and rescue notices and similar information to ships. A small, low-cost and self-contained "smart" printing radio receiver installed in the pilot house of a ship or boat checks each incoming message to see if it has been received during an earlier transmission, or if it is of a category of no interest to the ship's master. The frequency of transmission of these messages is 518 kHz in English, while 490 kHz is use to broadcast in local language.
The messages are coded with a header code identified by the using alphabets to represent broadcasting stations, type of messages, and followed by two figures indicating the serial number of the message.
===Inmarsat===
Satellite systems operated by the [[Inmarsat]], under contract to the [[International Mobile Satellite Organization]] (IMSO), are also important elements of the GMDSS. Four types of Inmarsat ship earth station terminals are recognized by the GMDSS: the Inmarsat A, B, C and F77. The Inmarsat B and F77, an updated version of the A, provide ship/shore, ship/ship and shore/ship telephone, telex and high-speed data services, including a distress priority telephone and telex service to and from rescue coordination centers. The F77 is meant to be used with the Inmarsat C, since its data capability does not meet GMDSS requirements. The Inmarsat C provides ship/shore, shore/ship and ship/ship store-and-forward data and email messaging, the capability for sending preformatted distress messages to a rescue coordination center, and the Inmarsat C SafetyNET service. The Inmarsat C SafetyNET service is a satellite-based worldwide maritime safety information broadcast service of high seas weather warnings, NAVAREA navigational warnings, radionavigation warnings, ice reports and warnings generated by the USCG-conducted International Ice Patrol, and other similar information not provided by NAVTEX. SafetyNET works similarly to NAVTEX in areas outside NAVTEX coverage.
Inmarsat C equipment is relatively small and lightweight, and costs much less than an Inmarsat A, B or F77. Inmarsat A, B and F77 ship earth stations require relatively large gyro-stabilized antennas; the antenna size of the Inmarsat C is much smaller. Inmarsat also operates an EPIRB system, the Inmarsat L, which is similar to that operated by COSPAS-SARSAT. The INMARSAT L (also called INMARSAT E) EPIRB system is terminated by November 30th, 2006. The INMARSAT EPIRBs are replaced by COSPAS-SARSAT EPIRBs with built-in GPS. Immediate alerting is possible through the GEOSAR satellites of the COSPAS-SARSAT system.
In July 2002 IMSO notified IMO of the decision by Inmarsat to withdraw provision of Inmarsat A services as from [[31 December]] [[2007]]. On that date, Inmarsat A can no longer be used for any purpose. The last type approval by Inmarsat for a new model of maritime Inmarsat A mobile earth station was granted in 1991, since then no new Inmarsat A models have been approved.
Under a cooperative agreement with the [[National Oceanic and Atmospheric Administration]] (NOAA), combined meteorological observations and [[AMVER]] reports can now be sent to both the USCG AMVER Center, and NOAA, using an Inmarsat C ship earth station, at no charge. .
SOLAS now requires that Inmarsat C equipment have an integral satellite navigation receiver, or be externally connected to a satellite navigation receiver. That connection will ensure accurate location information to be sent to a rescue coordination center if a distress alert is ever transmitted.
===High Frequency===
A GMDSS system may include [[High Frequency]] (HF) radiotelephone and [[teletype|radiotelex]] (narrow-band direct printing) equipment, with calls initiated by digital selective calling (DSC). Worldwide broadcasts of maritime safety information are also made on HF narrow-band direct printing channels.
===Search and Rescue Transponder===
{{main|Search and Rescue Transponder}}
The GMDSS installation on ships include one or more [[Search and Rescue Transponder]] (SART) devices which are used to locate survival craft or distressed vessels by creating a series of dots on a rescuing ship's 3 cm [[radar]] display. The detection range between these devices and ships, dependent upon the height of the ship's radar mast and the height of the SART, is normally about 15 km (8 nautical miles). Note that a marine radar may not detect a SART even within this distance, if the radar settings are not optimized for SART detection.
On detected by a radar, the SART will produce a visual and aural indication.
===Digital Selective Calling ===
The IMO also introduced [[Digital Selective Calling]] (DSC) on MF, HF and [[VHF maritime radio]]s as part of the GMDSS system. DSC is primarily intended to initiate ship-to-ship, ship-to-shore and shore-to-ship radiotelephone and MF/HF [[radiotelex]] calls. DSC calls can also be made to individual stations, groups of stations, or "all stations" in one's reach. Each DSC-equipped ship, shore station and group is assigned a unique 9-digit [[Maritime Mobile Service Identity]].
DSC distress alerts, which consist of a preformatted distress message, are used to initiate emergency communications with ships and rescue coordination centers. DSC was intended to eliminate the need for persons on a ship's bridge or on shore to continuously guard radio receivers on voice radio channels, including VHF channel 16 (156.8 MHz) and [[2182 kHz]] now used for distress, safety and calling. A listening watch aboard GMDSS-equipped ships on 2182 kHz ended on [[February 1]], [[1999]]. In May 2002, IMO decided to postpone cessation of a VHF listening watch aboard ships. That watchkeeping requirement had been scheduled to end on [[1 February]] [[2005]].
IMO and ITU both require that the DSC-equipped MF/HF and VHF radios be externally connected to a satellite navigation receiver. That connection will ensure accurate location information is sent to a rescue coordination center if a distress alert is ever transmitted. The FCC requires that all new VHF and MF/HF maritime radiotelephones type accepted after June 1999 have at least a basic DSC capability.
VHF digital selective calling also has other capabilities beyond those required for the GMDSS. The Coast Guard uses this system to track vessels in Prince William Sound, Alaska, Vessel Traffic Service. IMO and the USCG also plan to require ships carry a Universal Shipborne Automatic Identification System, which will be DSC-compatible. Countries having a GMDSS A1 Area should be able to identify and track AIS-equipped vessels in its waters without any additional radio equipment. A DSC-equipped radio cannot be interrogated and tracked unless that option was included by the manufacturer, and unless the user configures it to allow tracking.
GMDSS telecommunications equipment should not be reserved for emergency use only. The International Maritime Organization encourages mariners to use that equipment for routine as well as safety telecommunications.
==GMDSS Sea Areas==
GMDSS sea areas serve two purposes: to describe areas where GMDSS services are available, and to define what GMDSS ships must carry. Prior to the GMDSS, the number and type of radio safety equipment ships had to carry depended upon its tonnage. With GMDSS, the number and type of radio safety equipment ships have to carry depend upon the areas in which they travel. GMDSS sea areas are defined by governments.
In addition to equipment listed below, all GMDSS-regulated ships must carry a satellite EPIRB, a NAVTEX receiver (if they travel in any areas served by NAVTEX), an Inmarsat-C SafetyNET receiver (if they travel in any areas not served by NAVTEX), a DSC-equipped VHF radiotelephone, two or more VHF handhelds, and a search and rescue radar transponder (SART).
===Sea Area A1===
An area '''within the radiotelephone coverage of at least one VHF coast station''' in which continuous digital selective calling (Ch.70/156.525Mc.) alerting and radiotelephony services are available.Such an area could extend typically {{convert|20|nmi|km}} to {{convert|30|nmi|km}} from the Coast Station.
===Sea Area A2===
An area, excluding Sea Area A1, '''within the radiotelephone coverage of at least one MF coast station''' in which continuous DSC (2187.5 kHz) alerting and radiotelephony services are available.For planning purposes this area typically extends to up to {{convert|100|nmi|km}} offshore,but would exclude any A1 designated areas.In practice,satisfactory coverage may often be achieved out to around {{convert|400|nmi|km}} offshore.
===Sea Area A3===
An area, excluding sea areas A1 and A2, '''within the coverage of an INMARSAT [[geostationary satellite]]''' in which continuous alerting is available.This area lies between about latitude 76 Degree NORTH and SOUTH,but excludes A1 and/or A2 designated areas.
===Sea Area A4===
An area outside Sea Areas A1, A2 and A3 is called Sea Area A4. This is essentially the polar regions, north and south of about 76 degrees of [[latitude]], excluding any other areas.
===GMDSS Radio Equipment Required for U.S. Coastal Voyages===
Presently, until an A1 or A2 Sea Area is established, GMDSS-mandated ships operating off the U.S. coast must fit to Sea Areas A3 (or A4) regardless of where they operate. U.S. ships whose voyage allows them to always remain within VHF channel 16 coverage of U.S. Coast Guard stations may apply to the Federal Communications Commission for an individual waiver to fit to Sea Area A1 requirements. Similarly, those who remain within 2182 kHz coverage of U.S. Coast Guard stations may apply for a waiver to fit to Sea Area A2 requirements.
==History==
Since the [[invention of radio]] at the end of the 19th century, ships at sea have relied on [[Morse code]], invented by [[Samuel Morse]] and first used in 1844, for distress and safety telecommunications. The need for ship and coast radio stations to have and use radiotelegraph equipment, and to listen to a common radio frequency for Morse encoded distress calls, was recognized after the sinking of the liner [[RMS Titanic|RMS ''Titanic'']] in the North Atlantic in 1912. The [[Congress of the United States|U.S. Congress]] enacted legislation soon after, requiring U.S. ships to use Morse code radiotelegraph equipment for distress calls. The [[International Telecommunications Union]] (ITU), now a [[United Nations]] agency, followed suit for ships of all nations. Morse encoded distress calling has saved thousands of lives since its inception almost a century ago, but its use requires skilled radio operators spending many hours listening to the radio distress frequency. Its range on the [[medium frequency]] (MF) distress band ([[500 kHz]]) is limited, and the amount of traffic Morse signals can carry is also limited.
Not all ship-to-shore radio communications were short range. Some radio stations provided long-range radiotelephony services, such as radio [[telegram]]s and radio [[teleprinter#Telex|telex]] calls, on the [[high frequency|HF]] bands (3-30 [[MHz]]) enabling worldwide communications with ships. For example, [[Portishead Radio]], which was the world's busiest radiotelephony station, provided HF long-range, MF medium-range, and [[VHF]] short-range services;<ref name="johnson">{{cite journal
| author=Johnson, B
| title=English in maritime radiotelephony
| journal=World Englishes
| volume=13
| issue=1
| pages=83–91
| doi=10.1111/j.1467-971X.1994.tb00285.x
| year=1994}}</ref> in 1974, it had 154 radio operators who handled over 20 million words per year.<ref name="jproc">{{cite web
| title=The story of Portishead Radio: Long range maritime radio communications: 1920 – 1995
| date=2001-04-06
| url=http://jproc.ca/radiostor/portis1.html
| accessdate=2008-01-09}}</ref> Such large radiotelephony stations employed large numbers of people and were expensive to operate. By the end of the 1980s, satellite services had started to take an increasingly large share of the market for ship-to-shore communications.
For these reasons, the [[International Maritime Organization]] (IMO), a United Nations agency specializing in safety of shipping and preventing ships from polluting the seas, began looking at ways of improving maritime distress and safety communications. In 1979, a group of experts drafted the [[International Convention on Maritime Search and Rescue]], which called for development of a global search and rescue plan. This group also passed a resolution calling for development by IMO of a Global Maritime Distress and Safety System (GMDSS) to provide the communication support needed to implement the search and rescue plan. This new system, which the world's maritime nations are implementing, is based upon a combination of [[satellite]] and terrestrial radio services, and has changed international distress communications from being primarily ship-to-ship based to ship-to-shore (Rescue Coordination Center) based. It spelled the end of Morse code communications for all but a few users, such as [[amateur radio operator]]s. The GMDSS provides for automatic distress alerting and locating in cases where a radio operator doesn't have time to send an [[SOS]] or [[Mayday (distress signal)|MAYDAY]] call, and, for the first time, requires ships to receive broadcasts of maritime safety information which could prevent a distress from happening in the first place. In 1988, IMO amended the Safety of Life at Sea ([[International Convention for the Safety of Life at Sea|SOLAS]]) Convention, requiring ships subject to it fit GMDSS equipment. Such ships were required to carry NAVTEX and satellite EPIRBs by [[1 August]] [[1993]], and had to fit all other GMDSS equipment by [[1 February]] [[1999]]. US ships were allowed to fit GMDSS in lieu of Morse telegraphy equipment by the [[Telecommunications Act of 1996]].
==Licensing of Operators==
In the [[United States]] four different certificates are issued. A '''GMDSS Radio Maintainer's License''' allows a person to maintain, install,and repair GMDSS equipment at sea. A '''GMDSS Radio Operator's License''' is necessary for a person to use required GMDSS equipment. The holder of both certificates can be issued one '''GMDSS Radio Operator/Maintainer License'''. Finally, the '''GMDSS Restricted License''' is available for VHF operations only within {{convert|20|nmi|km}} of the coast. To obtain any of these licenses a person must be a U.S. citizen or otherwise eligible for work in the country, be able to communicate in English, and take written examinations approved by the [[Federal Communications Commission]]. Like the [[amateur radio]] examinations, these are given by private, FCC-approved groups. These are generally not the same agencies who administer the ham tests. Written test elements 1 and 7 are required for the Operator license, and elements 1 and 7R for the Restricted Operator. For the Maintainer examination element 9 must be passed. However, to obtain this certificate an applicant must also hold a [[General radiotelephone operator license]] ('''GROL'''), which requires passing commercial written exam elements 1 and 3. Upon the further passing of optional element 8 the '''ship radar endorsement''' will then be added to both the GROL and Maintainer licenses.<ref>[http://wireless.fcc.gov/commoperators/ FCC - Commercial Radio Operator Licenses<!-- Bot generated title -->]</ref>
Until [[March 25, 2008]] all GMDSS licenses could be renewed every five years upon payment of a fee. On that date new certificates became valid for the lifetimes of the holders. For those issued with expiration dates a final renewal is necessary. It should however be noted that to actually serve as an operator on most commercial vessels the [[United States Coast Guard]] requires additional classroom training and practical experience beyond just holding a license.<ref>[http://www.navcen.uscg.gov/marcomms/gmdss/tfib-tr.htm MarComms - GMDSS Training and Certification<!-- Bot generated title -->]</ref>
==Learning tools==
Many tools exist for teaching GMDSS skills, including various types of simulator. Simulators are very useful because sending false distress communications on live equipment is unsafe and illegal. A good simulator should faithfully reproduce conditions under which GMDSS systems would actually be used at sea. All of the questions and answers asked on the written tests are also available in commercially prepared books.
==See also==
{{nautical portal}}
* [[Marine VHF radio]]
* [[Search and Rescue Transponder]]
* [[Emergency Position-Indicating Radio Beacon]] ([[EPIRB]])
* [[Inmarsat]]
* [[Radio horizon]]
* [[500 kHz]]
* [[2182 kHz]]
==Source==
* http://www.navcen.uscg.gov/marcomms/gmdss/default.htm
* http://www.gmdss.com.au/
== References ==
<references/>
==External links==
* [http://www.prescom.net/maritime-radio-gmdss-dsc.html GMDSS Digital selective calling (DSC)]
* [http://www.cospas-sarsat.org/ COSPAS-SARSAT system home page]
* [http://www.voxmaris.com.ar Vox Maris Simulador GMDSS]
* [http://www.sarsat.noaa.gov/ Search And Rescue Satellite Aided Tracking (SARSAT)]
* [http://www.buffalocomputergraphics.com/gmdss.html Buffalo Computer Graphics GMDSS Simulator]
* [http://www.km.kongsberg.com/KS/WEB/NOKBG0240.nsf/AllWeb/1DA21A99E9433C47C1256DCD004A219E?OpenDocument Kongsberg Maritime GMDSS Simulator]
* [http://www.egmdss.com VHF GMDSS Simulator and Course]
* [http://wireless.fcc.gov/commoperators/exam.html FCC - Commercial Operator Licenes: Examinations] [[FCC]]
* [http://wireless.fcc.gov/commoperators/dm.html FCC - GMDSS Radio Maintainer's License (DM)] [[FCC]]
* [http://wireless.fcc.gov/commoperators/do.html FCC - GMDSS Radio Operator's License (DO)] [[FCC]]
* [http://wireless.fcc.gov/commoperators/sre.html FCC - Ship Radar Endorsement] [[FCC]]
* [http://wireless.fcc.gov/commoperators/eqp.html FCC - Commercial Operator Licenses: Examination Question Pools] [[FCC]]
* [http://www.fcc.gov/eb/ShipInsp/gmdss.html GMDSS Ship Inspection Checklist] [[FCC]]
[[Category:Emergency communication]]
[[Category:Law of the sea]]
[[Category:Maritime communication]]
[[Category:Rescue equipment]]
[[Category:Treaties]]
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