It is a current trend in aviation to use categories of technical (e.g., knowledge) and nontechnical skills (e.g., situation awareness) to assess airline pilots' performance. Several studies have revealed large disagreement between assessors when airline professionals use these categories to assess the performance of their peers. The aim of the present study is to investigate whether the categories themselves are at the source of disagreement. We explore the reasoning of flight examiners who assess an engine fire scenario in pairs. The results provide insight into the overlap of topics that constitute certain categories. Implications are drawn in regards to the use of assessment categories and their influence on pilot performance assessment.