What is the difference between AMRD Group A and AMRD Group B?.

AMRD Group A are identified as those that enhance the safety of navigation, while AMRD Group B are those that do not enhance the safety of navigation. The International Maritime Organisation (IMO) is the responsible organisation for these classifications.

Group A Includes:

• Man Overboard Devices using VHF DSC (Class-M)
• Mobile Aids to Navigation (Mobile AtoN)

A Man Overboard (MOB) device using VHF DSC (Class-M) is personal radio equipment (PRE) that alerts via Digital Selective Calling (DSC) and is tracked by the Automatic Identification System (AIS).

Only AMRD Group A devices are permitted to use Radio Regulations (RR) Appendix 18 frequencies, which are allocated for DSC (Channel 70, 156.525 MHz) and for AIS (AIS 1, 161.975 MHz) and (AIS 2, 162.025 MHz).

What is in AMRD Group B?

All other applications of AMRD, including MOB devices without DSC, fishnet markers, diver locating devices, etc., are in AMRD Group B. The IMO suggests that legacy AMRDs, categorised as Group B but using VHF channels AIS 1 and AIS 2, should no longer be placed on the market.