Class M FAQs

FREQUENTLY ASKED QUESTIONS WHAT IS THE Class-M REGULATION AND WHAT DOES IT MEAN? The “Class M” designation refers to Man Overboard (MOB) devices using VHF Digital Selective Calling (DSC), as defined

by ITU-R M.493 and ITU-R M.2135.

Under ECC/DEC/(22)02, Class M MOBs and Mobile Aids to Navigation (MAtoN) are the only AMRDs authorised to use AIS and DSC distress channels.

AIS-only MOBs and similar devices that lack DSC capability fall under Group B and, after 31 December 2024, may only operate on Channel 2006 (160.900 MHz) under restricted power (≤ 100 mW EIRP) and antenna height (≤ 1 m above sea surface). Channel 2006 is not monitored by emergency services.

Each CEPT country decides whether to adopt and enforce the decision nationally. Implementation status varies; an up-todate list is maintained at https://docdb.cept.org.

This change aims to reduce unnecessary or misleading AIS traffic generated by non-safety devices (such as net or gear markers) and to reserve key distress frequencies for recognised maritime safety functions.

WHAT IS ECC/DEC/(22)02?

WHY IS IT BEING INTRODUCED?

ECC/DEC/(22)02 is the Electronic Communications Committee Decision of 1 July 2022 issued by the European Conference of Postal and Telecommunications Administrations (CEPT).

The main objectives are to: Preserve the reliability of AIS 1 and 2 channels used for collision avoidance and vessel tracking.

Prevent congestion from non-essential transmissions by devices not related to vessel safety.

It establishes harmonised rules for the operation of Autonomous Maritime Radio Devices (AMRDs) within CEPT member countries.

The Decision divides AMRDs into two categories: • Group A – devices that enhance the safety of navigation.

• Group B – devices that do not enhance the safety of navigation.

Ensure DSC-based distress alerts are correctly prioritised and can be acknowledged and deactivated when resolved.

By distinguishing Group A and B, authorities can keep AIS frequencies clear for genuine safety-of-life applications.

Each group is assigned specific VHF frequencies, power limits, and operational conditions.

From 31 December 2024, only Group A devices will be permitted to use AIS 1 (161.975 MHz), AIS 2 (162.025 MHz), and DSC Channel 70 (156.525 MHz) in countries that implement this decision.

WHICH COUNTRIES DOES THE Class-M REGULATION AFFECT? ECC/DEC/(22)02 applies to all 46 CEPT member countries, but national implementation is voluntary.

As of 2025, countries including Germany, Italy, Belgium, and Denmark have formally adopted the decision, with others under review.

Each national administration (e.g. Ofcom in the UK) determines local enforcement and transition timelines.

WHAT MAKES MY DEVICE COMPLIANT? To qualify as a Class M MOB, a device must: Include an integrated GNSS receiver for position reporting.

Contain a DSC transceiver operating on VHF Channel 70 (156.525 MHz) capable of sending and receiving DSC messages.

The DSC receive function enables vessels to acknowledge alerts and remotely stop further distress transmissions, while the AIS signal continues to broadcast the location coordinates for visual tracking.

The FAQ above is our interpretation of the ECC legislation highlighted in document https://docdb.cept.org/document/28560

WHAT IS THE DIFFERENCE BETWEEN AMRD GROUP A & B?

WHO IS ENFORCING THE Class-M IMPLEMENTATION?

Group A (Enhances safety of navigation):

Implementation and enforcement rest with national spectrum authorities within CEPT member states.

• • • • • •

Man Overboard devices using VHF DSC (Class M).

Mobile Aids to Navigation (MAtoN).

Group A devices are authorised to operate on: DSC Channel 70 (156.525 MHz) AIS 1 (161.975 MHz) AIS 2 (162.025 MHz)

Group B (Does not enhance safety of navigation): Devices such as AIS-only MOBs, diver location aids, gear markers, and other autonomous transmitters not recognised as safety-critical. Group B devices may only operate on Channel 2006 (160.900 MHz) under the specified limits and are not permitted to use AIS 1 or 2 in CEPT countries that implement the Decision.

WHO IS RECOMMENDING THE Class-M IMPLEMENTATION? The Electronic Communications Committee (ECC) of CEPT recommended and adopted this regulation.

The ECC provides a European framework for technical and regulatory harmonisation of electronic communications, working alongside the European Commission and ETSI to ensure consistent spectrum management and safety standards.

For example, Ofcom oversees maritime radio licensing and spectrum compliance in the United Kingdom.

Authorities are responsible for defining national transition periods, licensing conditions, and equipment conformity checks.

HOW DO I KNOW IF MY MOB DEVICE IS Class-M COMPLIANT? Check your device specifications and certification documentation.

A Class M-compliant unit will explicitly include: • A VHF DSC transceiver (both transmit and receive functions).

• Compliance testing to applicable standards such as ETSI EN 303 132, EN 300 338-6, or equivalent national standard referencing ITU-R M.493.

If these features are absent, the device likely falls under Group B and may not be authorised for use on AIS 1 or 2 after national implementation.

WHAT HAPPENS IF USE A ‘NON-COMPLIANT’ DEVICE? In CEPT countries that have implemented ECC/DEC/(22)02:

WHAT IS THE DEADLINE FOR Class-M IMPLEMENTATION? The ECC Decision specifies that national administrations should withdraw authorisations for non-conforming devices on AIS 1 and 2 by 31 December 2024. From 1 January 2025, only Class M DSC MOB and Mobile AtoN devices should operate on those channels in adopting countries. Transition and enforcement timelines can differ, so users must verify local regulations.

• AIS-only MOBs and similar Group B AMRDs may not be licensed or operated on AIS 1 or 2 after 31 December 2024.

• Some administrations may authorise continued operation only on Channel 2006 under restricted conditions.

• Continued use on AIS channels may constitute a breach of national radio regulations.

• Users should check with their national authority to confirm permitted channels and registration requirements.

WHAT IS THE BENEFIT OF Class-M? Class M capability enhances safety by: Ensuring distress alerts are transmitted on an internationally recognised DSC emergency channel.

Allowing acknowledgement and deactivation of distress messages to reduce false or duplicate alerts.

Maintaining ongoing AIS position updates for rapid visual identification by nearby vessels and rescue services.

This dual-system approach improves both alerting reliability and search-and-rescue efficiency.

For more information please visit www.mrtsos.com/class-m The FAQ above is our interpretation of the ECC legislation highlighted in document https://docdb.cept.org/document/28560