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 diff erent 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 eff ects 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 Inmarsat-C and Inmarsat Fleet 77 terminals. However, in 2018 a new satellite system called Iridium has been recognized as a mobile satellite communication services provider in the GMDSS. Accordingly, this system and its capabilities are also introduced and briefl y described in this paper. In addition, authors have discussed impacts of the introduction of the new satellite system as a service provider in the GMDSS and addressed several emphasized issues related to this GMDSS modernization. Sažetak Dugo je satelitski sustav Inmarsat bio jedini pružatelj pokretnih satelitskih usluga u pomorstvu kada je u pitanju Svjetski pomorski sustav pogibelji i sigurnosti (Global Maritime Distress and Safety System -GMDSS). Ovaj satelitski sustav ima različite generacije svojih satelita koji pružaju širok spektar usluga i aplikacija. Njegove usluge vezane uz GMDSS 2018. godine preselile su se na noviju generaciju satelita. Migracija ovih satelitskih usluga sustavno se razmatra i analizira u ovom radu kako bi se čitatelji upoznali s njezinim učincima na sigurnost plovidbe. Nadalje, Inmarsat sustav najavio je novu uslugu pod nazivom Inmarsat Fleet Safety, koja će sadržavati i pružiti sve funkcionalne zahtjeve za GMDSS koji se trenutno pružaju Inmarsat-C i Inmarsat Fleet 77 terminalima. Međutim, 2018. godine novi satelitski sustav zvan Iridium prihvaćen je kao pružatelj pokretnih satelitskih komunikacijskih usluga u GMDSS-u. Sukladno s time, ovaj sustav i njegove mogućnosti također se predstavljaju i ukratko opisuju u ovom radu.Osim toga, autori detaljno analiziraju učinke uvođenja novog satelitskog sustava kao davatelja usluga u GMDSS-u te obraćaju pozornost na nekoliko istaknutih pitanja u vezi s ovom modernizacijom GMDSS-a.

The Automatic identification System (AIS) has been mainly designed to improve safety and efficiency of navigation, environmental protection, coastal traffic monitoring simplifying identification and communication. Additionally, historical AIS data have been used in many other areas of maritime safety, economic and environmental research. The probability of the detection of terrestrial AIS signals from space was presented in 2003, following the advancements in micro satellite technology. Through constant development, research and cooperation between governmental and private sectors, Satellite AIS (S-AIS) has been continuously evolving. Advancements in signal and data processing techniques have resulted in an improved detection over vast areas outside of terrestrial range. Some of the challenges of S-AIS technology include satellite revisit times, message collision and ship detection probability. Data processing latency and lacking the continuous real-time coverage made it less reliable for end user in certain aspects of monitoring and data analysis. Recent developments and improvements by leading S-AIS service providers have reduced latency issues. Complementing with terrestrial AIS and other technologies, near real-time S-AIS can further enhance all areas of the global maritime monitoring domain with emerging possibilities for maritime industry.

Global and regional positional accuracy assessment is of the highest importance for any satellite navigation system, including the Global Positioning System (GPS). Although positioning error can be expressed as a vector quantity with direction and magnitude, most of the research focuses on error magnitude only. The positional accuracy can be evaluated in terms of navigational quadrants as further refinement of error distribution, as it was shown here. This research was conducted in the wider area of the Northern Adriatic Region, employing the International Global Navigation Satellite Systems (GNSS) Service (IGS) data and products. Similarities of positional accuracy and deviations distributions for Single Point Positioning (SPP) were addressed in terms of magnitudes. Data were analyzed during the 11-day period. Linear and circular statistical methods were used to quantify regional positional accuracy and error behavior. This was conducted in terms of both scalar and vector values, with assessment of the underlying probability distributions. Navigational quadrantal positioning error subset analysis was carried out. Similarity in the positional accuracy and positioning deviations behavior, with uneven positional distribution between quadrants, indicated the directionality of the total positioning error. The underlying distributions for latitude and longitude deviations followed approximately normal distributions, while the radius was approximated by the Rayleigh distribution. The Weibull and gamma distributions were considered, as well. Possible causes of the analyzed positioning deviations were not investigated, but the ultimate positioning products were obtained as in standard, single-frequency positioning scenarios.

The characterization of ship routes and route similarity measurement based on Automatic Identification System (AIS) data are topics of various scientific interests. Common route research approaches use available AIS identifiers of ship types. However, assessing route and similarity profiles for individual fleets requires collecting data from secondary sources, dedicated software libraries or the creation of specific methods. Using an open-source approach, public AIS and ship data, we evaluate route characteristics for the container ships of a single fleet in a six-month period, calling on two selected ports of the shipping line on the USA East Coast. We evaluate the routes in terms of length, duration and speed, whereas for the similarity measurement we employ the discrete Fréchet distance (DFD). The voyage length, duration and average speed distributions were observed to be moderately positive (0.77), negative (−0.62), and highly positively skewed based on the adjusted Fisher–Pearson coefficient of skewness (1.23). The most similar voyages were from the same ships, with the lowest discrete Fréchet distance similarity value (0.9 NM), whereas 2 different ships had the most dissimilar voyages, with the highest DFD value (14.1 NM). The proposed methodology enables assessment of similarities between individual ships, or between fleets.