The three General Lighthouse Authorities (GLA) in the UK and Ireland (Trinity House, Northern Lighthouse Board & Irish Lights) as Afloat reported in 2020, will discontinue their Differential Global Positioning System (DGPS) service in March 2022.

(Click Irish Lights reminder of discontinuation of DGPS and related Irish Governments Dept. of Transport 'Notice to Mariners No. 4 of 2020' to discontinue the DGPS. In addition to highlighting 'Notice to Mariners No. 03 (2022) Page 2 of 2').

The GLAs made this decision after carefully considering the results from an extensive consultation carried out with stakeholders and service users.

It was in 1995 when the GLAs introduced DGPS as part of the mix of marine aids to navigation (AtoN) provided to safeguard mariners within their combined waters and to help protect the environment. The system became fully operational in 1997.

Maritime Safety

Following a change in maritime receiver standards in 2003, all receivers now include Receiver Autonomous Integrity Monitoring (RAIM). RAIM is a means of determining whether the resulting position estimate is safe to use through an algorithm within the receiver.

Differential corrections are also available from other sources, including Satellite Based Augmentation Systems (SBAS), which are primarily provided for aviation users.

Work is underway in Europe to introduce a maritime service to EGNOS, the European SBAS. This service is expected to be available around 2022. Vessels that need high accuracy position and integrity for operations mainly utilise a number of Commercial satellite-based services; the decision to discontinue DGPS has no operational impact on these services.

The GLAs advise mariners to consider their use of DGPS and to plan for its discontinuance accordingly. Mariners should check their GNSS receiver(s) to confirm the presence of RAIM and consider upgrading to type-approved SBAS receiving equipment when available.

The GLAs encourage mariners to use all available AtoN – whether visual or electronic – to support their safe passage and the protection of the environment.

Dr Alan Grant, Head of GLA Research and Development, said: “After careful consideration of the results of the consultation process, the three GLAs have concluded that their DGPS system is now redundant. Today’s GNSS are able to meet all but the most stringent accuracy requirements, and position integrity can be provided by alternative means (RAIM or other visual and electronic aids to navigation).

“The GLAs recognise the need to provide adequate notice and support continuity of service going forward. As such, the DGPS system will remain operational until 31 March 2022, at which point the signals will cease.”

For further reading, the full DGPS article by Dr Alan Grant is available to download here