Circular letter SN/Circ.217

 

 Interim Guidelines for the Presentation and Display of AIS Target Information

(adopted on 6 July 2001)

 

1. The Sub-Committee on Safety of Navigation (NAV), at its forty-seventh session, agreed on the interim Guidelines for the Presentation and Display of AIS Target Information.

 

2. The Guidelines deal with the graphical presentation and display of AIS target data in standalone or integrated navigational aids or systems and are considered as an interim performance guideline and should be replaced by appropriate amendments to existing performance standards for the relevant navigational aids after the marine community has gained the experience for final decisions on this matter.

 

3. These Interim Guidelines have been established for the development of the relevant equipment and functions in time, to allow mariners to acquaint themselves with the use of intelligent combination of information from the first date of AIS deployment.

 

4. Member Governments are invited to bring the annexed Interim Guidelines to the attention of all concerned.

 

Annex

INTERIM GUIDELINES FOR THE PRESENTATION AND DISPLAY OF AIS TARGET INFORMATION

1. Definitions

 

 

2. Operational requirements

 

In addition to the relevant performance standards, AIS information may be presented and displayed according to the following interim guidelines.

 

2.1 Presentation of information

 

2.1.1 If AIS information is made available for a graphical display, at least the following information should be displayed: (see resolution MSC.74(69), Annex 3 (AIS), paragraph 6):

 

.1 position;

 

.2 course over ground;

 

.3 speed over ground;

 

.4 heading; and

 

.5 rate of turn, or direction of turn, as available.

 

2.1.2 If information provided by AIS is graphically presented, the symbols described in the Appendix should be applied. In the case of a radar display, radar signals should not be masked, obscured or degraded.

 

2.1.3 Whenever the graphical display of AIS targets is enabled, the graphical properties of other target vectors should be equivalent to those of the AIS target symbols, otherwise the type of vector presentation, (radar plotting symbols or AIS symbols), may be selectable by the operator. The active display mode should be indicated.

 

2.1.4 The presentation of AIS target symbols, except for sleeping or lost targets, should have priority over other target presentations within the display area, including targets from EPA, ATA or ARPA. If such a target is marked for data display, the existence of the other source of target data may be indicated, and the related data may be available for display upon operator command.

 

2.1.5 The mariner should be able to select additional parts of the information from AIS targets, which should then be presented in the data area of the display, including the ship's identification, at least the MMSI. If the received AIS information is not complete, this should be indicated.

 

2.1.6 A common reference should be used for the superimposi-tion of AIS symbols with other information on the same display, and for the calculation of target properties (e.g. TCPA, CPA.).

 

2.1.7 If AIS information is graphically displayed on a radar, the equipment should be capable of appropriately stabilising the radar image and the AIS information.

 

2.1.8 Target data derived from radar and AIS should be clearly distinguishable as such

 

2.1.9 The operator may choose to display all or any AIS targets for graphical presentation. The mode of presentation should be indicated.

 

2.1.10 If the display of AIS symbols is enabled, removing a dangerous target should only be possible temporarily as long as the operator activates the corresponding control.

 

2.1.11 The AIS symbol of an activated target may be replaced by a scaled ship symbol on a large scale/small range display.

 

2.1.12 If the COG/SOG vector is shown, its reference point should be either the actual or the virtual position of the antenna.

 

2.1.13 Means should be provided to select a target or own ship for the display of its AIS data on request. If more than one target is selected, the relevant symbols and the corresponding data should be clearly identified. The source of the data, e.g., AIS, radar, should be clearly indicated.

 

2.2 Processing of information

 

2.2.1 If zones or limits for automatic target acquisition are set, these should be the same for automatically activating and presenting any targets regardless of their source.

 

2.2.2 The vector time set should be adjustable and valid for presentation of any target regardless of its source.

 

2.2.3 If radar plotting aids are used for the display of AIS information, these should be capable of calculating and displaying collision parameters equivalent to the available radar plotting functions.

 

2.2.4 If the calculated CPA and TCPA values of an AIS target are less than the set limits,

 

— a dangerous target symbol should be displayed and

 

- an alarm should be given.

 

The preset CPA/TCPA limits applied to target data derived from different sensors should be identical.

 

2.2.5 If the signal of a dangerous AIS target is not received for a set time:

 

— a lost target symbol should appear at the latest position and an alarm be given;

 

— the lost target symbol should disappear after the alarm has been acknowledged; and

 

— means to recover the data for a number of last acknowledged lost targets may be provided.

 

Preferably this function may also be applied to any AIS target within a certain distance.

 

2.2.6 An automatic display selection function may be provided
to avoid the presentation of two target symbols for the same
physical target. If target data from AIS and from radar plotting
functions arc available, then the activated AIS target symbol
should be presented, if the automatic selection criteria is fulfilled, otherwise the respective symbols should be displayed separately. The operator should have the option to make reasonable changes to the default parameters of automatic selection criteria.