Human Factor

           Duplicate Inspections are inspections where the task or process is performed by one person, a first check carried out by that person (if qualified to self-certify) or by a supervising certifying engineer, and then independent checks carried out by a second suitably qualified person. Both the first and second checks should be thorough and, in the case of control systems, ensure that they include functional checks for freedom and full range of movement. It is important to consider                      (i) the criticality of the task and consequences of failure,                                                          (ii) the vulnerability of the task to human error (which might be determined by previous incidents, a risk assessment, etc)    ...

           Functional checks are error capturing mechanisms in some instances since they will detect, if properly actioned, if something is not installed, secured properly, adjusted correctly or meets specified criteria in the manuals. This is true for most systems and is an inherent part of the maintenance process.          It is, in the majority of cases, impossible to carry out a duplicate inspection on a flying control without a function check since the range of movement, control stop clearances, control system friction or loading checks cannot be determined otherwise.                 The problem is that since they are regarded as an inherent part of the system, complacency can set in concerning their purpose and value. It is only when the function checks or ground runs are not carried out and an incident occurs, (e.g.  double engine oil loss on a 737-400 at Daventry) that their ...

           Whilst the system should aim for error avoidance, it is not always possible to prevent errors from happening, in which case, the next best thing is to detect them and prevent them from resulting in harm.                                                    The only sure way to be totally safe in aviation is to keep aircraft on the ground, but this is only an option in very extreme cases.        In normal operations, circumstances known to be vulnerable to error can often be avoided, or additional checks put in place to capture errors if they do occur.                                                     One example is work carried out when maintenance personnel are like...

 It is an ICAO standard for all organisations involved in the design, production, operations and maintenance of aircraft to have an occurrence reporting system. Part145.A.60 requires all Part-145 approved organisations to report occurrences meeting certain criteria1 to the competent authority, state of registry and organisation responsible for the design of the aircraft. Whilst this requirement is primarily intended for technical problems affecting aircraft, it also extends to errors where these have resulted in "any condition of the aircraft or component....that has resulted, or may result, in an unsafe condition that hazards seriously the flight safety" (Part145.A.60(a)). This could include, for instance, failure to refit O-ring seals when replacing chip detectors. In any case, each Part-145 approved organisation is required to have in place a system for the reporting, collection and evaluation of occurrences, the aim being "to identify the factors contributing to in...

 Evidence indicates that maintenance personnel often fail to comply with procedures. Part-145 necessarily requires, and assumes, compliance with procedures, but also addresses some of the issues which lead to non-compliance (e.g. poorly written procedures, unavailability of appropriate maintenance data or tooling, time pressure, etc.). “Procedures are not used because...                                    %agreeing                        Accuracy   ..they are inaccurate             21                                                                                        ...

 A working definition of “human error” (including violations) is “those occasions in which a planned sequence of mental or physical activities fails to achieve its intended outcome, and when these failures cannot be attributed to the intervention of some chance agency”.              It is useful to distinguish, right from the outset, the difference between "human error" and "system error".  Whilst it is always a human being who commits the error, there are two approaches to looking at error:  (i) from the point of view of the individual and  (ii) from the point of view of the whole system, of which the individual technician is only one part.  The concept of "maintenance error" is sometimes equated to "system error". Another useful way of looking at error (and violations) is in terms of system component failure, where human actions are part of the system and need to be engineered such that they are resistant to error and, in the...