In-flight upset - 154 km west of Learmonth, WA, 7 October 2008,

Researchers have stated that much more research needs to be done to fullyunderstand how expert design engineers conduct their work, and how to effectivelytrain novices to become experts. The research to date in this area has examined arange of design tasks, but limited research has focused on the task of reviewingsystem designs for safety-related problems. In addition, very little research haslooked at the ways that safety analysts conduct activities such as FHA, fault treeanalysis or FMEA.As well as understanding how design engineers and safety analysts conduct theirevaluations of system designs, it is important to understand the factors that canaffect the performance of these personnel. The aviation industry has applied anenormous amount of effort into studying the human factors 121 issues forsafety-critical personnel such as flight crew, air traffic controllers and aircraftmaintenance personnel, and ensuring their work tasks are appropriately designed.However, the investigation found very little research that has examined the humanfactors issues affecting design engineers and safety analysts, or systematicallyexamined the types of factors most likely to lead to design errors.The large amount of human factors research conducted in other domains couldprovide insights into the types of issues that may be relevant for design evaluationtasks. Strigini (1996) noted that research into human performance limitations hasidentified many factors could adversely affect engineering judgements, includingjudgements such as whether a fault tree is complete. For example, research hasshown that human decision-making ability can be affected by a range of differentfactors, such as task complexity, previous experiences, and the availableinformation or cues about the decision or problem (Klein 1998). In addition, systemdesign and evaluation is generally a team activity, with all design decisions beingreviewed by others. Research has shown that detecting errors in other people’sperformance can vary widely depending on the context, and that errors of omissionare relatively difficult to detect (Reason 1990). 122Although general human factors research can be applied to the work of designengineers and safety analysts, it would be more useful if research was specificallyconducted for design evaluation tasks. A key principle of human factors is that thespecific context in which work tasks are conducted needs to be well understood inorder to determine how the design of the tasks, tools, training and guidance materialcan be improved to minimise the likelihood of errors or increase the ability to detectsuch errors.121122Human factors is the scientific discipline concerned with understanding the interactions amonghumans and other elements of a system, and applying theory, principles, data and methods todesign in order to optimise safety, human well-being and overall system performance.Fischoff et al. (1978) and some other researchers (see Silvera 2005) have examined some biasesthat occur with fault tree analysis when information about some failure scenarios is omitted, butnone of this research has been conducted with experienced safety analysts.- 108 -