For a long time, Inmarsat satellite system was the only maritime mobile satellite service provider when Global Maritime Distress and Safety System (GMDSS) is concerned. This satellite system has different generations of its satellites providing a wide range of services and applications. In 2018, its services related to the GMDSS have migrated to a newer generation of satellites. This satellites’ services migration is systematically discussed and analysed in this paper in order to familiarize the readers with its effects on the safety of navigation. Furthermore, Inmarsat system announced a new service called Inmarsat Fleet Safety which will incorporate and provide all functional requirements for the GMDSS which are currently provided by Inma...