This article discusses the difficulties in utilising accident analysis as the basis for the development of complex socio-technical systems, and how to improve accident analysis to better meet such aims. It focuses on two themes: accident models and experts’ involvement in accident investigation. The article describes the development of a new core task analysis-based method for accident analysis. It also elaborates on the method by presenting summarising results of an investigation in which several maritime accidents were first analysed case-by-case, followed by a comparative analysis and a synthesis. The latter phases aimed at providing evident-based generic explanations for the accidents. The accidents occurred in Finnish coastal waters during sea or canal piloting between 1997 and 2000. The authors participated in both phases of the investigation for which the Finnish Accident Investigation Board was responsible. The presented method is argued to promote solutions to two current problems in accident investigation: generalisation from the results, and integration of the experts’ work.