Motivation – To explore the applicability of a Human Factors methodology for the investigation of fratricide. Research approach – The EAST methodology was used to analyse an incident of fratricide and its ability to explore the Famous Five of Fratricide (F3) model was investigated. Findings/Design – The analysis revealed that EAST was able to provide explicit discussion of the Famous Five of Fratricide (F3) models five causal factors of communication, cooperation, coordination, schemata and situation awareness. Research limitations/Implications – The research explored a single case study and as such is couched at the initial phases of investigation. Originality/Value – The analysis provides a contribution to the knowledge surrounding fratricide both with respect to the novel application of the EAST methodology to an incident of fratricide, and also the causal factors identified by EAST within the fratricide incident. Take away message – The EAST methodology provides an innovative way of exploring causality in incidents of fratricide.