The 12th session of the IMO’s Sub-Committee on Navigation, Communications, Search and Rescue (NCSR 12), held from 13 to 22 May 2025, marked an important step forward in maritime digitali- zation. NCSR 12 finalized draft SOLAS amendments to enable digital data exchange over VHF (VDES), advanced the framework for the digital broadcasting of maritime safety and search and rescue data from shore to ships (NAVDAT), and agreed on draft guidelines for software mainte- nance and for the use of electronic nautical publications. Progress was also made on connectivity guidelines to support the next generation of electronic navigational charts (ECDIS S-100).
Meeting highlights
•Finalized draft amendments to SOLAS Chapter V and related instruments to enable the digital exchange of data over VHF (VDES)
•Finalized draft guidelines for the software maintenance of shipboard navigation and communication equipment and systems
•Finalized draft guidelines on the carriage and use of the electronic nautical publications (ENP) system
•Agreed on a roadmap for the implementation of a digital system to broadcast MSI and SAR data from shore to ships (NAVDAT)
•Progressed the development of guidance for data distribu- tion and IP-based connectivity for the next generation of electronic navigational charts (ECDIS S-100)
Global Maritime Distress and Safety System (GMDSS)
Digital technology for VHF voice communications
NCSR 12 agreed to instruct the IMO/ITU Experts Group to undertake initial considerations on the development of a transition scheme for the introduction of digital technology for very-high frequency (VHF) voice communications, and to advise NCSR 13 accordingly. The initiative aims to guide the International Telecommunication Union (ITU) in considering the impact of its regulatory development on the maritime sector.
Dissemination of information over multiple satellite services
The IMO has agreed that maritime safety information (MSI) should be disseminated through all operational and recog- nized mobile satellite services (RMSS) by 31 December 2026. Since 1 January 2000, both Inmarsat and Iridium have been recognized for use in the GMDSS.
NCSR 12 agreed to draft amendments to SOLAS Regulations IV/5, V/4 and V/5 to explicitly require the dissemination of information related to maritime safety information (MSI) and search and rescue (SAR) through all operational RMSSs.
Draft amendments to Resolution MSC.509(105)/Rev.1 on the “Provision of Radio Services for the Global Maritime Distress and Safety System (GMDSS)” were also agreed accordingly.
The draft amendments will enter into force on 1 January 2028, subject to approval by MSC 110 (June 2025) and adop- tion by MSC 111 (May 2026).
Digital navigational data system (NAVDAT)
NAVDAT is intended for broadcasting digital data, including information related to MSI and SAR, on middle-frequency (MF) and high-frequency (HF) bands, from shore to ships.
A roadmap was updated in preparation for implementation of the NAVDAT service and forwarded to the IMO/ITU Experts Group for consideration. In addition, NCSR 12 updated the draft NAVDAT manual and agreed to forward it IHO and WMO for review.
Augmentation systems in Worldwide Radionaviga- tion System
Augmentation systems enhance the performance of Global Navigation Satellite Systems (GNSS) by improving attributes such as precision, reliability and availability. These enhance- ments are commonly referred to as differential corrections and integrity monitoring.
NCSR 12 agreed on draft amendments to Resolution A.1046(27) on the Worldwide Radionavigation System. The draft amend- ments provide additional clarification paragraphs on aug- mentation systems in the introduction of the annex of the resolution and add relevant requirements for augmentation systems under “Operational requirements” in its appendix.
A draft MSC resolution containing the amendments will be submitted to MSC 111 (May 2026) for adoption.
Based on the established procedures and requirements for augmentation systems, NCSR 12 agreed that it is now appro- priate to start the development of performance standards for dual-frequency multi-constellation satellite-based augmenta- tion systems (DFMC SBAS) and advanced receiver autono- mous integrity monitoring (ARAIM) in shipborne radionaviga- tion receivers. The work will be formally initiated at NCSR 13 (June 2026), subject to approval by MSC.
VHF Data Exchange System (VDES)
VDES is a digital communication system that operates over the VHF band to provide secure and reliable data exchange, for example between ships and between ships and shore.
VDES includes four components:
1.Automatic Identification System (AIS) component for the identification and tracking of vessels, along with additional communication capabilities
2.Application specific message (ASM) component
3.Terrestrial component for VHF data exchange (VDE-TER)
4.Satellite component for VHF data exchange (VDE-SAT)
NCSR 12 finalized draft amendments to SOLAS Chapter V and the appendix, as well as consequential amendments to the 1994 HSC Code and 2000 HSC Code, and associated performance standards and guidelines, to introduce the carriage of VDES.
The draft amendments will enter into force on 1 January 2028, subject to approval by MSC 110 (June 2025) and adoption by MSC 111 (May 2026).
Software maintenance of shipboard equipment and systems
NCSR 12 finalized new draft guidelines for the software maintenance of shipboard computer-based navigation and communication equipment and systems.
These guidelines are intended to ensure a controlled and standardized approach to software maintenance. It is, how- ever, important that any software installed in accordance with these guidelines should not compromise the type approval of the relevant equipment or systems.
The draft guidelines will be submitted to MSC for approval.
Procedure for responding to DSC distress alerts by ships
NCSR 12 agreed to a revision of the “Procedure for Respond- ing to DSC Distress Alerts by Ships” (MSC.1/Circ.1657).
The revision aligns the operational procedures for respond- ing to Digital Selective Calling (DSC) distress alerts with those prescribed in Recommendation ITU-R M.541-11 on “Opera- tional Procedures for the Use of Digital Selective Calling Equipment in the Maritime Mobile Service”.
The draft guidelines will be submitted to MSC 111 (May 2026) for approval.
Electronic nautical publications (ENP)
SOLAS Regulations V/19.2.1.4 and V/19.2.1.5 require all ships to have nautical charts and nautical publications, including back-up arrangements if this function is partly or fully fulfilled by electronic means, to plan and display the ship’s route
for the intended voyage and to plot and monitor positions throughout the voyage. Publications may be carried in the form of electronic media.
NCSR 12 finalized new draft guidelines on the carriage and use of the ENP system.
The draft guidelines will be submitted to MSC for approval.
BeiDou Navigation Satellite System (BDS)
NCSR 12 finalized a revision of Resolution MSC.379(93) on “Performance Standards for Shipborne BeiDou Satellite Navigation System (BDS) Receiver Equipment” to align the performance standards with the current service and perfor- mance of BDS.
Guidance for global ECDIS S-100 data connectivity NCSR 12 considered the draft of a guidance aimed at estab- lishing a framework for data distribution and global IP-based connectivity for shore-based facilities and ships supporting Electronic Chart Display and Information Systems (ECDIS) S-100 products.
The development of the guidance follows the adoption of a revised version of the ECDIS Performance Standards (Resolu- tion MSC.530(106)) in 2022, which enables the next technical generation of Electronic Navigational Charts.
The revised performance standards will apply to ECDIS equip- ment installed on or after 1 January 2029. During the transi- tional period from 1 January 2026 to 1 January 2029, ECDIS equipment may comply with either the current standards (Resolution MSC.232(82)) or the new performance standards.
The guidance for an IP-based S-100 data distribution frame- work will be progressed in a Correspondence Group until NCSR 13 in June 2026.
Recommendation
As NCSR 12 is a Sub-Committee, all decisions concerning rules, regulations and dates are subject to further considera- tion and approval by the Maritime Safety Committee (MSC). DNV recommends that our customers monitor the outcome of MSC 110 in June 2025 and MSC 111 in May 2026.
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