The errors described in incident reports were classified using a modified
version of the SRK model, with the addition of “procedure violations”
as a separate class of error, and the inclusion of perceptual errors,
such as inspection failures, in the skill-based category. Although procedure
violations were not the focus of the current study, they were
included for the sake of completeness as such actions are known to
feature in maintenance incidents (McDonald et al., 2000). Two coders
performed the error classification. The main coder (Rater 1) was an aviation
safety investigator with experience in the investigation of human
error in accidents and incidents.