The HET Practice
The HET practice (Figure 9) utilizes an outside error style classification system that was a result of an appraisal of current HEI systems and an assessment of occurrences of design-induced pilot faults. The HET error style classification is put into operation at each lowermost step in a Hierarchical Task Analysis of the flight mission that is being analyized in order to recognize any believable faults. The recognition of sound faults is founded on the analyst's personal decision and includes the analyst either witnessing the operation being carried out or performing the operation themselves (Stanton, et al., 2009). Their results showed that, of four practices used in isolation, analysts using the HET procedure presented the most
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All 37 mishaps contained at least one unsafe act perpetrated by the pilots. 25 of the mishaps were found to be “skill based errors.” 10 cases contained “Decision errors.” “Perceptual errors” were apparent in seven cases (Gaur, 2005). Further findings showed that defiance of rules and processes contributed in 16 mishaps. “Routine violations” contributed in 12 mishaps while “exceptional violations” occured less and aided in seven mishaps (Gaur, 2005). Mr. Gaur also found that a number of the mishaps contained a high percentage of one or more “pre-conditions for unsafe acts.” In fact, 23 of the 48 mishaps contained pre-conditions. 21 mishaps had “substandard condition of operators.” The commonplace being “physical/mental limitations” in 15 mishaps. Examples of these limitations were inexperience on type and the kind of flying such as in mountainous areas or amphibious, or flying a specific type of operation after a long absence. Further limitations included the capability to correctly understand English, such as instructions from an air traffic controller. Poor mental states helped to cause six mishaps and undesirable physiological states were attributed two mishaps. Below average procedures of operators was a factor in nine mishaps and of these, crew resource mismanagement was somewhat liable for six accidents.
All 37 mishaps contained at least one unsafe act perpetrated by the pilots. 25 of the mishaps were found to be “skill based errors.” 10 cases contained “Decision errors.” “Perceptual errors” were apparent in seven cases (Gaur, 2005). Further findings showed that defiance of rules and processes contributed in 16 mishaps. “Routine violations” contributed in 12 mishaps while “exceptional violations” occured less and aided in seven mishaps (Gaur, 2005). Mr. Gaur also found that a number of the mishaps contained a high percentage of one or more “pre-conditions for unsafe acts.” In fact, 23 of the 48 mishaps contained pre-conditions. 21 mishaps had “substandard condition of operators.” The commonplace being “physical/mental limitations” in 15 mishaps. Examples of these limitations were inexperience on type and the kind of flying such as in mountainous areas or amphibious, or flying a specific type of operation after a long absence. Further limitations included the capability to correctly understand English, such as instructions from an air traffic controller. Poor mental states helped to cause six mishaps and undesirable physiological states were attributed two mishaps. Below average procedures of operators was a factor in nine mishaps and of these, crew resource mismanagement was somewhat liable for six accidents.