Notice To Mariners

Region D

8/2012 AIS




No.8/12 B1, C4, D1, E3, F3, G1


Automatic Identification System (AIS)


Use of AIS as an Aid to Navigation (AtoN)



The General Lighthouse Authorities¹ (GLA) have commenced roll out of AIS AtoN at selected fixed and floating stations on the coasts of Great Britain and Ireland.


It is considered appropriate to remind mariners of the purpose of AIS AtoN and what they may expect to see on some of the available displays.


It is important to bear in mind that the information available to mariners will be dependent on their display system and not all transmitted information may be displayed.


AIS Transmissions are currently exhibited from the following Trinity House stations:-




MMSI Number

Cromer Lighthouse

Lat 52° 55’.482N., Long 001° 18’.990E


Orfordness Lighthouse

Lat 52° 05’.033N., Long 001° 34’.459E


North Foreland Lighthouse

Lat 51° 22’.494N., Long 001° 26’.705E


Southwold Lighthouse

Lat 52° 19’.632N., Long 001° 40’.886E




Displays & Symbology

The IMO mandatory carriage requirement for Class A² AIS display is the Minimum Keyboard Display which displays the data in alphanumeric form.


It is important to bear in mind that not all vessels are equipped with AIS. Of those vessels that are AIS equipped the displays available can range from no display on some Class B² units, through the mandatory Class A MKD, to full ECDIS and Radar overlay. In the absence of ECDIS or Radar overlay users will not be able to fully utilise AIS AtoN functionality.

There is also a variance on information that will be displayed by different manufacturers on ECDIS or Radar equipment.


The symbology that may be displayed on nautical charts, display systems and MKD is summarised below.



Nautical Charts      -         On nautical charts AIS AtoN are indicated by a magenta circle   surrounding the existing AtoN symbol and an adjacent legend stating AIS.           The font will be straight for fixed AtoN and italic for floating AtoN.







Display Systems             -         Where AIS is provided as an overlay on ECDIS, Radar or other display systems AIS AtoN are indicated by a Diamond shape with crossed lines at the reported position of the AtoN. Where the AtoN is on station the diamond will be Blue and where the AtoN Off Station flag has been activated the diamond will be Red. In the case of a Virtual AIS³ AtoN there will be a V below the crossed lines.



Range       Bearing    Name





Latitude               XXX XX.XXX

Longitude          XXX XX.XXX


Minimum Keyboard Display       -         The mandatory Minimum Keyboard Display (MKD) is only required to display data in alphanumeric form. Some MKD are units supplemented by a small graphical display. Exact presentation will vary but the layout opposite would be typical of MKD displays.






Message Types.


AIS stations provided by the GLA will transmit Message 21 – Aids to Navigation Report.


Message 21 – Aids to Navigation report. This message will provide details of the Name, MMSI, Type and Position of the AtoN. In addition there will be an indication if the AtoN is off station, and of the status of the light, Racon or other equipment.


Other messages providing additional data may occasionally be broadcast. These would normally be Binary Messages 6/8 or Short Safety Related Messages 12/14.


Details of AIS AtoN are set out in Volume 2 of the Admiralty List of Radio Signals.



Mariners are requested to contact the General Lighthouse Authorities regarding their experience of AIS and in particular the extent to which AIS AtoN data is available to them.



By Order,


Captain R. H. Barker


Director of Navigational Requirements.


Trinity House,

London EC3N 4DH

31st January, 2012




¹           The General Lighthouse Authorities (GLA) consist of Trinity House (England & Wales), Northern Lighthouse Board (Scotland) and the Commissioners of Irish Lights (Ireland).


²           Class A AIS units are those meeting the mandatory SOLAS carriage requirements (SOLAS Chapter V, Rule 19) for vessels over 300GRT. Class B AIS units are for use on craft that are not covered by the mandatory carriage requirements.


³           Virtual AIS AtoN are used to mark new dangers / wrecks or in circumstances where a physical AtoN cannot be established. The AtoN does not physically exist and therefore will only be visible on display systems.



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