EASA Module 8 key terms

The study of how people's physical, mental and social capabilities interact with the job, the equipment and the surroundings, used to make maintenance work safer and more reliable.

The observation that if something can be done the wrong way, sooner or later someone will do it; used to justify designing parts and checks so that a single mistake cannot cause harm.

A set of twelve well-known precursors of maintenance error, including fatigue, complacency, distraction, poor communication and lack of resources, taught so that staff can recognise conditions that breed mistakes.

A person's current mental picture of the task, the equipment and the surroundings; when it is lost or wrong, people act on outdated information and errors follow.

The mental resource that selects what a person concentrates on; it is limited, easily captured by distractions, and can only be shared between tasks with a drop in performance.

The sharpness of vision, meaning the smallest detail the eye can resolve; it falls in dim light, with increasing age and away from the centre of gaze.

An intense fear of confined places such as tanks, ducts and wheel wells, which can trigger panic, rapid breathing and a strong urge to get out during inspection work.

Influence from workmates to behave in a certain way, such as skipping a check or not wearing protective equipment, which can push a person into unsafe acts in order to be accepted.

The shared attitudes, beliefs and everyday behaviour of an organisation towards safety, revealed by what people actually do and report rather than by what the written policy says.

A working climate in which honest mistakes and near-misses can be reported and learned from without unfair punishment, while deliberate or reckless breaches are still dealt with firmly.

The direction, checking and support given by the person in charge of a team; effective supervision sets clear standards, matches work to ability and spots problems early.

People cooperating on a shared task with clear roles, open communication and mutual checking, so that one person's limits or mistakes are caught by the others.

The body's reaction to demands it feels unable to meet; mild short-term stress can help performance, but prolonged stress harms sleep, concentration and judgement and raises error rates.

Tiredness caused by long hours, hard work, poor sleep or a disturbed body clock; it slows reactions, weakens attention and greatly increases the chance of making an error.

The roughly 24-hour internal cycle that governs sleepiness, alertness and body temperature; night work and crossing time zones upset it and lower performance.

Rotas that include night, early and late shifts; they disturb sleep and body rhythms, and alertness is naturally at its lowest in the early hours of the morning.

The sense that a job must be finished in too little time, which encourages rushing, shortcuts and skipped checks and is a common contributor to maintenance error.

The mental and physical effort a task demands; too much leads to overload and mistakes, while too little brings boredom, lost attention and missed warning signs.

The drug contained in alcoholic drinks, which slows the brain and impairs judgement, coordination and reaction time; effects can outlast the drinking session, so rules set a minimum time before duty.

Prescribed or over-the-counter medicines that can cause drowsiness, dizziness or slowed reactions; staff must read the warnings and report anything that could affect safe work.

Unwanted sound in the workplace; it can drown out speech and warnings, distract, add to fatigue and, at high levels, damage hearing, so both loudness and exposure time matter.

Permanent ear damage from repeated or long exposure to loud sound; it develops slowly, causes no pain and cannot be reversed, so hearing protection and limits on exposure are essential.

The amount and quality of light falling on a task; poor light, glare or weak contrast hides fine detail, causes eyestrain and leads to missed defects during inspection.

The strain produced by working in a hot place, causing sweating, dehydration, tiredness and poor concentration, and so a higher chance of mistakes and accidents.

Rapid shaking transmitted to the body from tools, engines or aircraft motion; it can blur vision, numb the hands and speed up tiredness during long tasks.

Lifting, lowering, carrying, pushing or pulling loads by hand; heavy or awkward loads and poor technique cause back and limb injuries, so aids and good posture are needed.

Tasks performed many times in the same way, which become automatic and can bring boredom, drifting attention and failure to notice that something has changed.

Looking over an aircraft, engine or component for defects such as cracks, corrosion, leaks or loose parts; reliability depends on light, eyesight, attention and knowing what to look for.

Passing information so that the receiver understands it as intended; this needs clear standard wording, a check that it was understood and no assumptions about shared knowledge.

The transfer of task status, unfinished work and known problems from one shift to the next, best done face to face and backed by written notes so that nothing is lost.

Writing down tasks done, defects found, parts fitted and actions taken in the approved records as work proceeds, giving an accurate and traceable history of the aircraft.

Being up to date with the knowledge and skill a task requires, maintained through recent practice, recurrent training and access to the latest manuals and instructions.

Any unintended act or failure to act by a person that departs from what was intended or required; it is normal and unavoidable, so defences must catch errors before they cause harm.

A skill-based error in which a well-practised action is carried out wrongly, such as using the wrong tool or turning a fastener the wrong way, often when attention is diverted.

An error that comes from a wrong plan or a wrong understanding of the situation, so the action goes as intended but is the wrong thing to do.

A deliberate departure from a rule or procedure, often made to save time or effort and often tolerated by the group; unlike a slip, it is a chosen act.

A picture of how accidents happen in which each layer of defence has holes; harm results only when the holes in every layer line up and a hazard passes through all of them.

Anything with the potential to cause harm, such as a fuel spill, an unguarded rotating part, poor lighting, a loose panel or an unmarked excavation.

Telling the responsible person about a dangerous condition or near-miss through the formal system so that it can be fixed and others warned, without fear of blame.

Going inside a tank, duct or other enclosed volume where room is limited and the air may be unsafe; it requires ventilation, an attendant outside, permits and rescue arrangements.