Hi Dawntreader,
The following is a copy of the IMO regulation, and from it you will see that ships are required to have the system in use at all times except in situations where ship security is at risk. Unfortunately we live in troubled times, and an AIS signal for example, would be a homing signal for the likes of Pirates operating off the Horn of Africa. In such circumstances ships are permitted to turn off their AIS, but if they did, as an OCIMF or CDI ship inspector, I would expect to see a log book entry clearly stating why the system had been turned off, and in the absence of such entry the ship concerned would have an observation raised which while having no legal standing would severely hamper the vessels ability to trade. It would also be seen by Port State Control Inspectors who have the legal right to detain the ship until they are satisfied that the regulations are being followed. Such detention would also have a detrimental effect on the vessels ability to trade.
A further situation also needs to be taken into account and that is in regard to vessels carrying flammable cargoes such as oil, gas and chemical tankers where the output power of any transmitter onboard was required to be below 1 watt (it might be 2 watts now), or it was to be switched off during all cargo operations. Those operations usually take place in port, but not always as ships often transfer cargo during a ship to ship transfer at some offshore location. Such operations happen very frequently. Most AIS class A transmitters that I am aware of transmit at 2 watts or more and would in the circumstances be switched off in order to prevent the possibility of incendive sparking. (Not a great thing to happen in places where flammable liquids and gasses are present).
Passenger and other ships periodically need to load fuel and gas oil (diesel fuel), and would be required to observe the same restrictions during the loading as tankers. People make mistakes and occasionally they might forget to switch on their AIS after such operation. That's not an excuse for not switching it on, just a reason.
Sometimes also the text message contained in regard to the vessels destination may not have been updated, such that occasionally you will see, for example, a ship where the text message says it is travelling towards a specific port, but where it's heading is clearly away from that port, and not just marking time while waiting for the tide or a pilot. So while not right, the information needs to be read with care and things like the actual direction of travel being taken into consideration.
The text of the IMO reg follows, I hope this helps:-
Radio Communications and Search and Rescue
Home » Our Work » Maritime Safety » Navigation » Automatic Identification Systems (AIS)
AIS transponders
Automatic identification systems (AISs) are designed to be capable of providing information about the ship to other ships and to coastal authorities automatically.
Regulations for carriage of AIS
Regulation 19 of SOLAS Chapter V - Carriage requirements for shipborne navigational systems and equipment - sets out navigational equipment to be carried on board ships, according to ship type. In 2000, IMO adopted a new requirement (as part of a revised new chapter V) for all ships to carry automatic identification systems (AISs) capable of providing information about the ship to other ships and to coastal authorities automatically.
The regulation requires AIS to be fitted aboard all ships of 300 gross tonnage and upwards engaged on international voyages, cargo ships of 500 gross tonnage and upwards not engaged on international voyages and all passenger ships irrespective of size. The requirement became effective for all ships by 31 December 2004.
Ships fitted with AIS shall maintain AIS in operation at all times except where international agreements, rules or standards provide for the protection of navigational information.
A flag State may exempt ships from carrying AISs when ships will be taken permanently out of service within two years after the implementation date. Performance standards for AIS were adopted in 1998.
The regulation requires that AIS shall:
provide information - including the ship's identity, type, position, course, speed, navigational status and other safety-related information - automatically to appropriately equipped shore stations, other ships and aircraft;
receive automatically such information from similarly fitted ships; · monitor and track ships;
exchange data with shore-based facilities.
The regulation applies to ships built on or after 1 July 2002 and to ships engaged on international voyages constructed before 1 July 2002, according to the following timetable:
passenger ships, not later than 1 July 2003;
tankers, not later than the first survey for safety equipment on or after 1 July 2003;
ships, other than passenger ships and tankers, of 50,000 gross tonnage and upwards, not later than 1 July 2004.
An amendment adopted by the Diplomatic Conference on Maritime Security in December 2002 states that, additionally, ships of 300 gross tonnage and upwards but less than 50,000 gross tonnage, are required to fit AIS not later than the first safety equipment survey after 1 July 2004 or by 31 December 2004, whichever occurs earlier. (The original regulation adopted in 2000 exempted these vessels.)
Maritime security - AIS ship data
At its79th session in December 2004, the Maritime Safety Committee (MSC) agreed that, in relation to the issue of freely available automatic information system (AIS)-generated ship data on the world-wide web, the publication on the world-wide web or elsewhere of AIS data transmitted by ships could be detrimental to the safety and security of ships and port facilities and was undermining the efforts of the Organization and its Member States to enhance the safety of navigation and security in the international maritime transport sector.
The Committee condemned the regrettable publication on the world-wide web, or elsewhere, of AIS data transmitted by ships and urged Member Governments, subject to the provisions of their national laws, to discourage those who make available AIS data to others for publication on the world-wide web, or elsewhere from doing so.
In addition, the Committee condemned those who irresponsibly publish AIS data transmitted by ships on the world-wide web, or elsewhere, particularly if they offer services to the shipping and port industries.
Further information
Resolution A.917(22) Guidelines for the onboard operational use of shipborne automatic identification systems (AIS) - available from your national maritime Administration or purchase Assembly resolutions from IMO Publications.
Resolution MSC.74(69) includes Recommendation on Performance Standards for Universal Automatic Identification System (AIS) available from your national maritime Administration
Related Documents
SN/Circ.227 Guidelines for the installation of a Shipborne Automatic Identification System (AIS) (197 KB)
Related Links
IMO Publications
So you will also see that this regulation does not allow for filtering of AIS a signals and hence the stances from my earlier posting as well as that from Maritimo, as filtering would clearly be contrary to the requirement of the regulation.
