The purpose of this chapter is to introduce the perceptual cycle model (PCM; Neisser, 1976), and its incorporation of Schema Theory, as a way of examining the process of aeronautical decision-making. A qualitative method is presented in which the PCM is used as a coding scheme to analyse data elicited from the critical decision method (CDM; Klein et al., 1989). In the previous chapter, the PCM was presented as a way to structure accident report data in order to infer explanations for decision-making. This chapter seeks to explore whether the PCM can be applied to interpret CDM data and how reliable this approach is. After introducing the relevant theoretical and methodological perspectives, the remainder of the chapter is split into three parts: Section 4.3 analyses a critical incident in relation to the PCM, Section 4.4 addresses the reliability of this method and Section 4.5 provides a general discussion of the practical implications and applications of this approach.