Various methods have been proposed to analyse safety and risk of maritime transportation, through
modelling techniques and empirical studies, focusing on ship–ship collision. However, an efficient
method for screening traffic data for the near miss collisions is lacking. Therefore the contribution of this
paper is two-fold. First, it proposes a novel method detecting possible near miss ship–ship collisions
from AIS data. Second, it discusses how such near miss data can be used to gain further insight in safety
of maritime transportation. The developed Vessel Conflict Ranking Operator (VCRO) considers the
following factors affecting the complexity of an encounter between two ships: the distance between the
two ships, the relative speed of the ships, and the difference between the headings of the ships. The
model content and structure are based on expert judgment, whereas the parameterisation is based on
AIS data points of a reference encounter situation dataset. The developed model has been applied to the
traffic data from the Northern Baltic Sea. The obtained results and the model validity tests suggest the
model being adequate for ranking encounters, and for prioritising the encounters to subject to further
expert scrutiny