Resolution A.917(22) 

GUIDELINES FOR THE ON BOARD OPERATIONAL USE OF SHIPBORNE AUTOMATIC IDENTIFICATION SYSTEMS (AIS)

(adopted on 29 November 2001)

 

THE ASSEMBLY,

 

RECALLING Article 15(j) of the Convention on the International Maritime Organization concerning the functions of the Assembly in relation to regulations and guidelines concerning maritime safety;

 

RECALLING ALSO the provisions of regulation V/19 of the International Convention for the Safety of Life at Sea, 1974, as amended, requiring all ships of 300 gross tonnage and upwards engaged on international voyages and cargo ships of 500 gross tonnage and upwards not engaged on international voyages and passenger ships irrespective of size to be fitted with an automatic identification system (AIS), as specified in regulation V/19, paragraph 2.4, taking into account the recommendations adopted by the Organization;

 

HAVING CONSIDERED the recommendations made by the Maritime Safety Committee at its seventy-third session and the Sub-Committee on Safety of Navigation at its forty-seventh session;

 

1. ADOPTS the Guidelines for the on Board Operational Use of Shipborne Automatic Identification Systems (AIS) set out in Annex to the present resolution;

 

2. INVITES Member Governments concerned to take into account these Guidelines when implementing SOLAS regulations V/11, 12 and 19;

 

3. ALSO INVITES Member Governments, that set regional frequencies, requiring manual switching which, from the safety viewpoint, should be limited to temporary situations, to notify the Organization of those areas and designated frequencies for circulation of that information until 1 April 2002;

 

4. REQUESTS the Maritime Safety Committee to keep the Guidelines under review and amend them as appropriate,

 

 

Annex.

GUIDELINES FOR THE ONBOARD OPERATIONAL USE OF SHIPBORNE AUTOMATIC IDENTIFICATION SYSTEMS (AIS)

 

PURPOSE

 

1. These Guidelines have been developed to promote the safe and effective use of shipborne Automatic Identification Systems (AIS), in particular to inform the mariner about the operational use, limits and potential uses of AIS. Consequently, AIS should be operated taking into account these Guidelines.

 

2. Before using shipborne AIS, the user should fully understand the principle of the current Guidelines and become familiar with the operation of the equipment, including the correct interpretation of the displayed data. A description of the AIS system, particularly with respect to shipborne AIS (including its components and connections), is contained in Annex 1.

 

 

 

 

3. The internationally-adopted shipborne carriage requirements for AIS are contained in SOLAS regulation V/19. The SOLAS Convention requires AIS to be fitted on certain ships through a phased implementation period spanning from 1st July 2002 to 1st July 2008. In addition, specific vessel types (e.g. warships, naval auxiliaries and ships owned/operated by governments) are not required to be fitted with AIS. Also, small vessels (e.g. leisure craft, fishing boats) and certain other ships are exempt from carrying AIS. Moreover, ships fitted with AIS might have the equipment switched off. Users are therefore cautioned to always bear in mind that information provided by AIS may not be giving a complete or correct "picture" of shipping traffic in their vicinity. Guidance in this document on the inherent limitations of AIS and their use in collision avoidance situations (see paragraphs 39 to 40) should, therefore, be heeded.

 

OBJECTIVES OF AIS

 

4. AIS is intended to enhance: safety of life at sea; the safety and efficiency of navigation; and the protection of the marine environment. SOLAS regulation V/19 requires that AIS exchange data ship-to-ship and with shore-based facilities. Therefore, the purpose of AIS is to help identify vessels; assist in target tracking; simplify information exchange (e.g. reduce verbal mandatory ship reporting); and provide additional information to assist situation awareness. In general, data received via AIS will improve the quality of the information available to the OOW, whether at a shore surveillance station or on board a ship. AIS should become a useful source of supplementary information to that derived from navigational systems (including radar) and therefore an important "tool" in enhancing situation awareness of traffic confronting users.

 

DESCRIPTION OF AIS 

 

Figure 1.
AIS system overview

 

 

 

 

 

 

5. Shipborne AIS

 

— continuously transmits ship's own data to other vessels and VTS stations,

 

— continuously receives data of other vessels and VTS stations, and

 

— displays this data.

 

6. When used with the appropriate graphical display, shipborne AIS enables provision of fast, automatic information by calculating Closest Point of Approach (CPA) and Time to Closest Point of Approach (TCPA) from the position information transmitted by the target vessels.

 

7. AIS operates primarily on two dedicated VHF channels. Where these channels are not available regionally, the AIS is capable of being automatically switched to designated alternate channels by means of a message from a shore facility. Where no shore based AIS or GMDSS sea Area A1 station is in place, the AIS should be switched manually.

 

8. In practice the capacity of the system is unlimited allowing for a great number of ships to be accommodated at the same time.

 

9. The AIS is able to detect ships within VHF/FM range around bends and behind islands, if the landmasses are not too high. A typical value to be expected at sea is 20 to 30 nautical miles depending on antenna height. With the help of repeater stations, the coverage for both ship and VTS stations can be improved.

 

10. Information from a shipborne AIS is transmitted continuously and automatically without any intervention or knowledge of the OOW. An AIS shore station might require updated information from a specific ship by "polling" that ship, or alternatively, might wish to "poll" all ships within a defined sea area. However, the shore station can only increase the ships' reporting rate but not decrease it.

 

AIS INFORMATION SENT BY SHIPS 

Ship's data content

 

11. The AIS information transmitted by a ship is of three different types:

 

— fixed, or static information, which is entered into the AIS on installation and need only be changed if the ship changes its name or undergoes a major conversion from one ship type to another;

 

— dynamic information, which, apart from "Navigational status" information, is automatically updated from the ship sensors connected to AIS; and

 

— voyage-related information that might need to be manually entered and updated during the voyage.

 

12. Details of the information referred to above are given in table 1 below:

 

 

Table 1.
Data sent by ship

 

 

13. The data is autonomously sent at different update rates:

 

— dynamic information dependent on speed and course alteration (see Table 2),

 

— static and voyage-related data every 6 minutes or on request (AIS responds automatically without user action).

 

 

Table 2:
Report Rate of Dynamic Information

 

 

Short safety related messages

 

14. Short safety-related messages are fixed or free format text messages addressed either to a specified destination (MMSI) or all ships in the area. Their content should be relevant to the safety of navigation, e.g. an iceberg sighted or a buoy not on station. Messages should be kept as short as possible. The system allows up to 158 characters per message but the shorter the message the easier it will find free space for transmission. At present, these messages are not further regulated, to keep all possibilities open.

 

15. Operator acknowledgement may be requested by a text message.

 

16. Short safety-related messages are only an additional means to broadcast maritime safety information. Whilst their importance should not be underestimated, the usage of such short safety-related message does not remove any of the requirements of the Global Maritime Distress Safety System (GMDSS).

 

17. The operator should ensure that he displays and considers incoming safety-related messages and should send safety-related messages as required.

 

18. According to SOLAS regulation V/31 (Danger messages):

 

"The master of every ship which meets with dangerous ice, a dangerous derelict, or any other direct danger to navigation, or ... is bound to communicate the information by all the means at his disposal to ships at his vicinity, and also to the competent authorities ..."

 

19. Normally this is done via VHF voice communication but by all the means now implies the additional use of the AIS short messages application, which has the advantage to reduce difficulties in understanding, especially when noting down the correct position.

 

Confidentiality

 

20. When entering any data manually, consideration should be given to the confidentiality of this information, especially when international agreements, rules or standards provide for the protection of navigational information.

 

OPERATION OF AIS ON BOARD

OPERATION OF THE TRANSCEIVER UNIT 

Activation

 

21. AIS should always be in operation when ships are underway or at anchor. If the master believes that the continual operation of AIS might compromise the safety or security of his/her ship, the AIS may be switched off. This might be the case in sea areas where pirates and armed robbers are known to operate. Actions of this nature should always be recorded in the ship's logbook together with the reason for doing so. The master should however restart the AIS as soon as the source of danger has disappeared. If the AIS is shut-down, static data and voyage related information remains stored. Restart is done by switching on the power to the AIS unit. Ship's own data will be transmitted after a two minute initialization period. In ports AIS operation should be in accordance with port requirements.

 

Manual input of data

 

22. The OOW should manually input the following data at start of the voyage and whenever changes occur using the input device such as a keyboard:

 

— ship's draught;

 

— hazardous cargo;

 

— destination and ETA;

 

— route plan (way-points);

 

— the correct navigational status; and

 

— safety related short messages

 

Check of information

 

23. To ensure that own ship's static information is correct and up-to-date, the OOW should check the data whenever there is a reason for it. As a minimum, this should be done once per voyage or once per month whichever is shorter. The data may be changed only on the authority of the master.

 

24. The OOW should also periodically check the following dynamic information:

 

— positions given according to WGS 84;

 

— speed over ground; and

 

— sensor information.

 

25. After activation an automatic built-in integrity test (BIIT) is performed. In the case of any AIS malfunction an alarm is provided and the unit should stop transmitting.

 

26. The quality or accuracy of the ship sensor data input into AIS would not however be checked by the BIIT circuitry before being broadcast to other ships and shore stations. The ship should therefore carry out regular routine checks during a voyage to validate the accuracy of the information being transmitted. The frequency of those checks would need to be increased in coastal waters.

 

DISPLAY OF AIS DATA

 

27. The AIS provides data that can be presented on the minimum display or on any suitable display device as described in annex 1.

 

Minimum display

 

28. The minimum mandated display provides not less than three lines of data consisting of bearing, range and name of a selected ship. Other data of the ship can be displayed by horizontal scrolling of data, but scrolling of bearing and range is not possible. Vertical scrolling will show all the other ships known to the AIS.

 

Graphical display

 

29. Where AIS information is used with a graphical display the following target types are recommended for display:

 

 

Symbols

 

30. The user should be familiar with the symbology used in the graphical display provided.

 

INHERENT LIMITATIONS OF AIS

 

31. The officer of the watch (OOW) should always be aware that other ships, and in particular leisure craft, fishing boats and warships, and some coastal shore stations including Vessel Traffic Service (VTS) centres might not be fitted with AIS.

 

32. The OOW should always be aware that other ships, fitted with AIS as a mandatory carriage requirement, might switch off AIS under certain circumstances by professional judgement of the master.

 

33. In other words, the information given by the AIS may not be a complete picture of the situation around the ship.

 

34. The users must be aware that transmission of erroneous information implies a risk to other ships as well as their own. The users remain responsible for all information entered into the system and the information added by the sensors.

 

35. The accuracy of AIS information received is only as good as the accuracy of the AIS information transmitted.

 

36. The OOW should be aware that poorly configured or calibrated ship sensors (position, speed and heading sensors) might lead to incorrect information being transmitted. Incorrect information about one ship displayed on the bridge of another could be dangerously confusing.

 

37. If no sensor is installed or if the sensor e.g. the gyro) fails to provide data, the AIS automatically transmits the "not available" data value. However the built-in integrity check cannot validate the contents of the data processed by the AIS.

 

38. It would not be prudent for the OOW to assume that the information received from other ships is of a comparable quality and accuracy as that which might be available on own ship.

 

USE OF AIS IN COLLISION AVOIDANCE SITUATIONS

 

39. The potential of AIS as an anti-collision device is recognized and AIS may be recommended as such a device in due time.

 

40. Nevertheless AIS information may be used to assist in collision avoidance decision-making. When using the AIS in the ship-to-ship mode for anti-collision purposes, the following cautionary points should be borne in mind:

 

.1 AIS is an additional source for navigational information. AIS does not replace, but supports, navigational systems such as radar target-tracking and VTS; and

 

.2 the use of AIS does not negate the responsibility of the OOW to comply, at all times, with the Collision Regulations.

 

41. The user should not rely on AIS as the sole information system, making use of all safety-relevant information available.

 

42. The use of AIS on board ship is not intended to have any special impact on the composition of the navigational watch, which should continue to be determined in accordance with the STCW Convention.

 

43. Once a ship has been detected, AIS can assist in tracking it as a target. By monitoring the information broadcast by that target, its actions can also be monitored. Changes in heading and course are, for example, immediately apparent, and many of the problems common to tracking targets by radar, namely clutter, target swap as ships pass close by and target loss following a fast manoeuvre, do not affect AIS. AIS can also assist in the identification of targets, by name or call sign and by ship type and navigational status.

 

ADDITIONAL AND POSSIBLE FUTURE APPLICATIONS

 

AIS IN VTS OPERATIONS 

 

Pseudo AIS information

 

44. VTS centres may send information about vessels which are not carrying AIS and which are tracked only by VTS radar, via the AIS to vessels equipped with AIS. Any pseudo AIS target broadcast by VTS should be clearly identified as such. Particular care should always be taken when using information which has been relayed by a third party. Accuracy of these targets may not be as accurate as actual directly-received targets and the information content may not be as complete.

 

Text messages

 

45. VTS centres may also send short messages either to one ship, all ships or ships within a certain range or in a special area, e.g.:

 

— (local) navigational warnings;

 

— traffic management information; and

 

— port management information.

 

46. A VTS operator may request, by a text message, an acknowledgement from the ship's operator.