In this paper, we introduce a new Human Reliability Analysis method based on a Human Abilities Theory Model (HRA-HAT). This approach simultaneously addresses cross-cutting aspects of the main issues and criticisms of human reliability models: 1) model's theoretical bases (including taxonomy and concept specificity); 2) definition and use of performance shaping factors; and 3) HRA quantification. HAT is used to support method parameters selection and the consequent data collection procedure. The resulting methodology works on the basis of three main stages: 1) Fuzzy Cognitive Task Analysis; 2) Fuzzy Operator Analysis; and 3) Fuzzy Human Error Probability estimation based on Human Abilities Theory model. “Operator Analysis” is a new stage of HRA that reduces uncertainty about individuals’ actual behavior in specific situations by focusing on this essential component of sociotechnical systems. To exemplify method implementation procedures, an illustrative example is analyzed. Finally, methodology sensibility and uncertainty are explored in order to prompt HRA-HAT validation. Since this methodology was conceived as an approach applicable to several fields, it is expected to be revised and adapted for further practical applications.