The Skill Assumption -Over-Reliance on Perception Skills in Hazard Assessment

In the analysis of human performance and human error, considerable attention is given to the cognitive processes of actors involved in error or success scenarios. Even with awareness of hindsight bias, it takes effort to understand the actions of agents in later inspection of error scenarios. One such topic of heated discussion was the perceived poor performance of pilots in the two 737 MAX MCAS-related crashes in applying the “memory item” checklist pertaining to a runaway trim. In this paper, we argue that it is not so much the reproduction of the checklist that was lacking in these scenarios, but the trigger for even starting the checklist. Not only trim run-away problems, but several other issues likewise require an instant reaction from pilots, designated as “memory items”. Rasmussen’s simplifed schematic for the “skill, rule and knowledge” taxonomy already provides the tools for properly analyzing this. The skill to provide the triggers for these reactions relies on pattern extraction from the available sensory input, and, importantly, it can only be learned in a valid training context. It is argued that re-appraisal of these items is needed, addressing explicitly the validity of the training environments that enable pilots to learn the required pattern recognition skills