Aircraft maintenance errors are estimated to be involved in 12%
of airline accidents worldwide. Records maintained by the
Australian Transport Safety Bureau (ATSB) indicate that 4.5% of
Australian aircraft accidents involve maintenance deficiencies.
Human error in aircraft maintenance is poorly understood and has
not been the subject of previous studies in Australia. In late 1998
the Bureau of Air Safety Investigation (now ATSB) distributed a
survey to Licensed Aircraft Maintenance Engineers (LAMEs) in
Australia. The survey was designed to identify safety issues in
maintenance, with a particular emphasis on the human, or
nontechnical aspects of the job.
The survey provided LAMEs with the opportunity to describe
occurrences that had the potential to threaten the safety of an
aircraft, or the safety of maintenance workers. Six hundred and ten
occurrence reports were reported via the survey. In most cases the
reported events resulted in relatively minor consequences. The most
common form of occurrence was one in which an aircraft system was
activated in an unsafe manner during maintenance. The next most
common form of occurrence involved the incomplete installation of
components. Over 95% of the occurrences involved the actions of
people. The most common forms of human error contributing to the
events were memory lapses and procedure shortcuts. The contributing
factors most frequently listed by survey respondents were time
pressure, equipment deficiencies, inadequate training, coordination
difficulties and fatigue. There was evidence that the frequency of
safety occurrences fluctuated throughout the 24 hour day and that
the early hours of the morning were times of particular risk for
maintenance occurrences.
Several safety deficiencies were identified in the course of
this study. These included: a current lack of programs to limit the
extent of fatigue experienced by maintenance workers; a lack of
recurrent training for licenced aircraft maintenance engineers; a
need for maintenance personnel to be trained in crew resource
management skills such as communication and the management of
production pressures; a widespread blame culture in aircraft
maintenance which discourages personnel from officially reporting
incidents; and the simultaneous maintenance of critical multiple
redundant systems, which can make the consequences of errors more
serious. The report concludes with recommendations directed at
these issues.