The Commissioners of Irish Lights issues Notices to Mariners regarding damage of Aids to Navigation, AIS/AtoN and the discontinuation DPGS

The Commissioners of Irish Lights issues Notices to Mariners

The Commissioners of Irish Lights has issued three Notices to Mariners regarding care to avoid damaging Aids to Navigation, the use of AIS as an Aid to Navigation (AtoN) and on the discontinuation of the Differential Global Positioning System (DPGS).


The Commissioners of Irish Lights request mariners navigating around the coast of Ireland to exercise the greatest care to avoid damage to Aids to Navigation.

Mariners should give all Aids to Navigation a wide berth, paying particular attention to the strength of wind and tide.

When an Aid to Navigation fails there is significant risk to the mariner and the environment, and it is essential that the relevant authorities are informed immediately so that any loss of service can be restored as quickly as possible.

All are requested to report immediately a defect with any Aid to Navigation to the Irish Lights 24-Hour Monitoring Centre telephone number +353-1-2801996, or to the Coast Guard.

The Merchant Shipping Acts make provision for the imposition of a fine on any person who wilfully or negligently runs foul of, makes fast to, interferes with or damages any Lighthouse, Buoy, Beacon, or any other Aid to Navigation and such person will be liable for the recovery of the expenses for making good any resulting damage.

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The Commissioners of Irish Lights operate a number of lighthouses at which boat landings exist. As these lighthouse sites are unmanned, the landings may no longer be maintained and the Commissioners of Irish Lights accepts no liability for injuries or damage resulting from unauthorised access to these sites.

Mariners are invited to contact the eNavigation and Maritime Services Department, Commissioners of Irish Lights ([email protected]) to comment on any aspect of the Aids to Navigation Service or on hazards to navigation around the coast of Ireland.



The General Lighthouse Authorities (GLA) continue to provide AIS AtoN at selected fixed and floating stations on the coasts of Great Britain and Ireland.

AIS AtoN are Aids to Navigation under the Merchant Shipping Acts and as such Statutory Sanction for their provision is required from the General Lighthouse Authority for the area in which they are established. Application forms are available at It is considered appropriate at this time to repeat some guidance to mariners on the purpose of AIS AtoN and what they may expect to see on some of the available displays.

Displays & Symbology

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

The information available to mariners will be dependent on their display system and not all transmitted information may be displayed. Mariners are encouraged to install systems that provide AIS overlay on ECDIS and radar. Mariners are cautioned against using websites that purport to provide accurate AIS data, as the source and the age of this data can be unreliable.

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 (minimum keyboard and display), 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:

irish lights mariners notices

Message Types

AIS stations provided by the GLA will transmit 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 8/10 or short safety-related messages 12/14. The Commissioners of Irish Lights provide live wind and sea-state data from a number of AIS AtoN and also provide this information over the internet and Twitter, see Details of AIS AtoN are set out in Volume 2 of the Admiralty List of Radio Signals.


The Commissioners of Irish Lights is continuing to expand its AIS Met/ Hydro Service as per Irish Lights Notice to Mariners No. 05 of 2014. 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.



The Commissioners of Irish Lights wishes to remind mariners of the contents of previously issued Notice to Mariners 04-2020. After careful consideration of the results of a comprehensive user consultation process, the General Lighthouse Authorities for the UK and Ireland have concluded that their Differential Global Positioning System (DGPS) is no longer required and have made the decision that the system will be discontinued from 31 March 2022.

The (DGPS) Service for UK and Ireland was established at a time when the publicly available GPS signal was intentionally degraded, resulting in large position errors. Augmentation was necessary to correct for these errors and meet minimum requirements for maritime positioning and navigation. In the year 2000, the intentional error in GPS positioning was removed. Since then, system technology has improved and the GPS constellation has been modernised. Observed positional accuracy for unaugmented GPS now consistently meets IMO requirements for accuracy around the coast of the UK and Ireland for marine navigation.

How will the discontinuation impact you?

For the vast majority of maritime users, the discontinuation of DGPS service for the UK and Ireland will not impact the accuracy of satellite positioning. DGPS receivers will no longer receive the DGPS signal in areas where it was previously available. This may generate a ‘lost signal’ alarm, but your receiver will still provide a GPS derived position.

Alternate sources for high accuracy positioning

Other options are available for obtaining higher accuracy positioning in the UK and Ireland.

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