AIS-derived port-calling opportunity modelling in conflict-affected waters

The long-standing protracted conflicts surrounding the coastal breakaway territory of Abkhazia in Georgia and the occupied territories in Eastern Ukraine have contributed to a complex maritime operating environment. Detecting anomalous vessel behaviour in such environments remains challenging, particularly where prolonged Automatic Identification System (AIS) transmission gaps may obscure vessel movements. This study draws on a historical dataset of over 27 million AIS transmission signals from the Eastern Black Sea for the year 2018 to examine patterns of AIS transmission loss in conflict-affected waters. A Discrete Port Calling Opportunities Model (DPCOM), combined with a grid-based statistical framework, is applied to identify plausible port-calling opportunities associated with prolonged AIS transmission gaps and to evaluate their spatial distribution. The results demonstrate that DPCOM-selected trajectories are strongly associated with statistically significant anomaly hotspots and identify recurring patterns of AIS transmission loss. The study creates a reproducible framework for analysing prolonged AIS transmission gaps, highlighting the value of large-scale behavioural analytics for maritime domain awareness in conflict-affected coastal environments.