In this paper we describe a case study comparing the effectiveness of three indirect knowledge elicitation techniques: repertory grid analysis, multi-dimensional scaling, and hierarchical clustering. These techniques are used in situations where it is difficult for the expert to articulate their knowledge in response to direct questions. The techniques were compared in terms of the number of attributes elicited, the ease with which these data were obtained, and the degree of post-analysis and interpretation required. The study was conducted in the domain of airline safety inspections and the objective was to define inspection indicators. The results of this study indicate that the repertory grid analysis method generates all of the attributes produced by the other two methods, that it is easy to apply in the field, and is useful without complex analysis and re-interpretation of the results.