Human Factor

Potential Hazards in Aircraft Maintenance  very bright lights (e.g. from welding); very loud sounds (sudden or continuous);  confined or enclosed areas; working at significant heights; noxious substances (liquids, fumes, etc.); excessive temperature (i.e. too cold or too hot);  moving equipment, moving vehicles and vibration. Health and safety policy Carry out assessments of work including inspections to determine H&Safety risks; Provide safe working practices and procedures for plant, machinery, work equipment, materials and substances; Inform employees and other persons including temporary workers of any risk; Provide suitable training and/or instruction to meet any Health and Safety risks; Develop and introduce practices and procedures to reduce risks to Health and Safety including the provision of special protective devices and personal protective equipment; Provide for the welfare of employees; Discuss with and consult employee rep...

Human information processing  have limitations.   AMT requires support such as reference  to written material (e.g. manuals). Attention and Perception -  A proportion of ‘sensed’ data may be lost without being                              ‘perceived’.   Failing to  perceive  something  which   someone  has said to you, when you are concentrating on something else, even  though the words would have been received at the ear without any problem.  Information processing system has  ability  to perceive   something (such as a picture,                       sentence, concept, etc.) even though some of the data  may be missing.  Danger - people can fill in the gaps with  information from their own store of knowledge or experience, and this may lead to  t...

  SMS provide a means of achieving enhanced safety performance which meets or exceeds basic compliance with the regulatory requirements associated with safety and quality. It is a well-established fact that enhanced safety performance is founded upon a proactive safety culture inherent in all the organisation’s safety-related activities.  A corporate approach to safety must be able to meet the following criteria: • Published safety accountabilities of managers and key staff • Requirements for a safety manager • The ability to demonstrate that it generates a positive safety culture throughout the organisation • Documented business policies, principles and practices in which safety is inherent • Commitment to a safety oversight process which is independent of line management • Regularly reviewed safety improvement plans • Formal safety review process The second essential prerequisite is for an organisation that delivers safe standards by way of: • Effective arrangem...

 Where procedures allow some leeway, AMT often develop  their own strategies or preferred way of carrying out a task. Often, a ‘good’ rule or  principle is one that has been used successfully in the past.  These good rules become   ‘rules of thumb’ that an engineer might adopt for day-to-day use.  Problems occur   when the rule or principle is wrongly applied. For example, aircraft pipe couplings are   normally right-hand threads but applying thi  s ‘normally good rule’ to an oxygen pipe   (having a different thread) could result in damage to the pipe. Also, there can be   dangers in applying rules based on previous experience if, for example, the design philosophy differs, as in the case of Airbus and Boeing. This may have been a factor in an A320 locked spoiler incident, where subtle differences between the operation of the spoilers on the A320 and those of the B767 (with which the engineers were more familiar) meant that act...

S kill, rule, knowledge-based errors; Skill-based behaviours  are those that rely on stored routines or motor programmes that have been learned with practice and may be executed without conscious thought. Rule-based behaviours  are those for which a routine or procedure has been learned. The components of a rule-based behaviour may comprise a set of discrete skills. Knowledge-based behaviours  are those for which no procedure has been established. These require to evaluate information, and then use  knowledge and experience to formulate a plan for dealing with the situation.”

S lips, lapses and mistakes ;  Slips  can be thought of as actions not carried out as intended or planned, e.g. ‘transposing digits when copying out numbers, or misordering steps in a procedure. Lapses  are missed actions and omissions, i.e. when somebody has failed to do something  due to lapses of memory and/or attention or because they have forgotten something, e.g.  forgetting to replace an engine cowling.    Mistakes  are a specific type of error brought about by a faulty plan/intention, i.e. somebody  did something believing it to be correct when it was, in fact, wrong, e.g. an error of  judgement such as mis-selection of bolts when fitting an aircraft windscreen.          Violations  sometimes appear to be human errors, but they differ from slips, lapses  and mistakes because they are deliberate ‘illegal’ actions,

PEAR model is developed by Dr. William Johnson and Dr. Michel Maddox specifically with the maintenance in mind. P - People - who do the job E - Environment - in which they work A - Action they perform R - Resource -necessary to complete the job.

Aircraft engineer  involved in inspection tasks, to  have adequate vision to meet the task requirements.   Age  and problems developing in the eye itself can gradually affect vision.  Without regular  vision testing, AMT may not notice that their vision is  deteriorating.   CAA  guidance which states:              “A reasonable standard of eyesight is needed for any aircraft engineer to perform his duties to an acceptable degree. Many maintenance tasks require a combination of both distance and near vision. In particular, such consideration must be made where there is a need for the close visual  inspection of structures or work related to small or miniature components. The use of glasses or contact lenses to correct any visionproblems is perfectly acceptable and indeed they must be worn as  prescribed.  Frequent checks should be made to ensure the continued adequacy of any glasses or...

 O ne team passes on tasks to another team . I nformation conveyed include: tasks that have been completed; tasks in progress, their status, any problems encountered, etc.;  tasks to be carried out; general company and technical information. Communication between teams  involves passing on written reports of tasks from  one shift supervisor to another -  backed up by spoken details Written reports (job cards, procedures, work orders, logs,  etc.)  Warning flags / placards provide a record of work completed and work yet to  be completed -  provide tractability.  Information communicated at shift handover ensures good continuity. It is important that handovers are not rushed, so as to minimize omissions. Communication Problems - lack of communication -  engineer who forgets to pass on pertinent information to a colleague,      or when a  written message is mislaid. Poor communication . -  ...

           Although not directly affecting visual acuity, inability to see particular colours can be a problem for the aircraft maintenance engineer. Good colour  vision for maintenance engineers is important for:                     • Recognising components;                     • Distinguishing between wires;ლ                     • Using various diagnostic tools;                    • Recognising various lights on the airfield (e.g. warning lights). Colour defective vision is usually hereditary, although may also occur as a temporary  condition after a serious illness. Degrees of colour defective vision , some people suffering more than  others. Individuals may be able to distinguish between red and green in a well-lit  situation but...

Eye is very sensitive in the right conditions (e.g. clear air, good light, etc.),  has approx 1.2 million nerve cells leading from the retinas to the area  of the brain responsible for vision, while there are only about 50,000 from the inner  ears - making the eye about 24 times more sensitive than the ear. Visual acuity  is the ability of the eye to discriminate sharp detail at varying distances. Visual acuity is affected by: (a)  Physical factors such as: •      physical imperfections in one or both eyes (short sightedness, longsightedness), •      age. •      The influence of ingested foreign substances such as: •      drugs,  medication,  alcohol,  cigarettes (b)  Environmental factors such as: •      amount of light available  clarity of the air (e.g. dust, mist, rain, etc.). •      Factors asso...

  Noise Induced Hearing Loss (NIHL)  -  Hearing loss can result from exposure to even relatively short duration noise. The degree of impairment is influenced mainly by the intensity of the noise. Such damage is known as Noise Induced Hearing Loss (NIHL).   Hearing loss can be temporary - lasting from a few seconds to a few days - or permanent.     Temporary hearing loss may be caused by relatively short exposure to very loud sound, as the hair-like cells on the basilar membrane take time to ‘recover’. With additional exposure, the amount or recovery gradually decreases and hearing loss becomes permanent. Thus, regular exposure to high levels of noise over a long period may permanently damage the hairlike cells in the cochlea, leading to irreversible hearing impairment. Three levels of noise at which an employer must act:      a) 85 decibels (if normal speech cannot be heard clearly at 2 metres), employer must;      ...

Noise levels can be reduced (attenuated) by up to 20 decibels using ear plugs and 40 decibels using ear muffs . However, using ear protection will tend to adversely interfere with verbal communication.  It is good practice to reduce noise levels at source, or move noise away from workers. Hearing  protection should always be used for noise, of any duration, above 115 dB.   AME will almost  always need to use some form of hearing protection when in reasonably close  proximity (about 200 - 300m) to aircraft whose engines are running. Presbycusis - Hearing deteriorates naturally as one grows older. This is known as presbycusis.  Presbycusis affects ability to hear high pitch sounds first, and may occur gradually from the 30’s  onwards. When this natural decline is exacerbated by Noise Induced Hearing Loss, it  can obviously occur rather sooner.

          Perception  involves the organisation and interpretation of sensory data in order to make it meaningful, discarding non-relevant data, i.e. transforming data into information. Perception is a highly sophisticated mechanism and requires existing knowledge and experience to know what data to keep and what to discard, and how to associate the data in a meaningful manner.        Perception can be defined as the process of assembling sensations into a useable mental  representation of the world. Perception creates faces, melodies, works of art, illusions,  etc. out of the raw material of sensation.        Decision making  is the generation of alternative courses of action based on available information, knowledge, prior experience, expectation, context, goals, etc. and selecting one preferred option.         Decision making is also described as thinking, problem...