ATPL 040 Human Performance key terms

A condition in which the tissues receive an inadequate supply of oxygen, causing impaired judgement, euphoria, cyanosis and loss of consciousness, with four types: hypoxic, hypemic, stagnant and histotoxic.

The period from the loss of oxygen supply at altitude until a person becomes unable to take corrective action, roughly 15 to 30 seconds at FL 400 and several minutes at FL 250.

Overbreathing that lowers arterial carbon dioxide, producing dizziness, tingling, chest tightness and visual disturbance; its symptoms resemble hypoxia, so oxygen and controlled breathing are the first response in flight.

The loss of cabin pressure differential, either explosive (under about one second) or rapid, causing a sudden drop in ambient pressure, fog formation, temperature fall and an immediate need for oxygen.

Formation of nitrogen bubbles in blood and tissues when ambient pressure falls too quickly after exposure to higher pressure, causing joint pain, skin mottling, respiratory or neurological symptoms; prevented by pre-breathing oxygen and avoiding diving before flight.

Tissue injury caused by a pressure difference across a gas-filled cavity that cannot equalise, most commonly affecting the middle ear, sinuses, teeth and gut during climb or descent.

A pressure-equalisation technique in which the pilot pinches the nose and gently blows against a closed mouth while swallowing, forcing air through the Eustachian tube into the middle ear during descent.

The maintenance of cabin altitude below the aircraft's actual altitude, typically not above 8,000 ft, through controlled outflow of air, protecting occupants from hypoxia and decompression sickness.

An incorrect perception of the aircraft's position, attitude or motion relative to the earth, arising when vestibular and visual information conflict, especially without external visual references in cloud or at night.

A false sensation of pitch caused by linear acceleration or deceleration, such as the impression of climbing during take-off acceleration or of pitching down during deceleration, leading to inappropriate control input.

The inner-ear organs, semicircular canals and otoliths, that sense angular and linear acceleration; they cannot distinguish gravity from acceleration and provide misleading cues in sustained flight without visual reference.

Misleading perceptions of reality produced by the limitations of the eyes and ears, such as black hole approaches, false horizons, runway width effects and the leans, which can be reduced by relying on instruments.

Nausea, pallor, sweating and malaise provoked by conflicting motion signals from the eyes, vestibular organs and body senses; it is managed by avoiding head movement, flying visually and using acclimatisation.

G-induced loss of consciousness, resulting from reduced blood flow to the brain under sustained acceleration; it is preceded by visual greyout and blackout and is countered by the anti-G straining manoeuvre and G-suits.

The internal roughly 24-hour biological cycle that regulates alertness, body temperature and hormone release, driven by the body clock and entrained by light; it is disrupted by night flying and time-zone crossing.

A temporary desynchronisation of the body clock after rapid travel across time zones, causing disturbed sleep, reduced alertness and slower performance until the rhythm re-entrains over several days.

A physiological state of reduced mental or physical performance capability resulting from sleep loss, extended wakefulness, circadian phase or workload, impairing alertness and reaction time even when the person feels normal.

A reversible state of reduced responsiveness essential for restoring alertness, consisting of cycles of non-REM and REM stages; cumulative loss of sleep degrades vigilance and decision making.

The mental and physical effort required to meet task demands; when demand exceeds capacity the pilot becomes overloaded and performance breaks down, while too little demand leads to underload and boredom.

The general level of activation or alertness of a person; performance is best at moderate arousal, while very low arousal produces boredom and very high arousal produces stress and narrowed attention.

The body's response to demands that exceed its perceived ability to cope, producing physiological and psychological effects that can improve short-term performance but impair judgement and coordination when prolonged.

A human-factors framework describing the interaction of Software, Hardware, Environment and Liveware, with the central Liveware representing the person whose mismatches with the other components cause error.

An unintentional action or omission by a person that deviates from intended or required behaviour; it is classified as a slip, lapse, mistake or violation and is usually a symptom of deeper system weaknesses.

A list of twelve common human-factors precursors to maintenance and operational error, including fatigue, complacency, distraction, pressure, lack of communication, lack of resources and lack of teamwork.

The accurate perception of the elements in the environment, comprehension of their meaning and projection of their future state; it is lost through fixation, ambiguity, overload and failure to monitor.

The effective use of all available resources, including people, equipment and information, through communication, leadership, teamwork and decision making to improve flight safety.

The willingness to state one's concerns clearly and respectfully, and to persist until acknowledged, particularly when a junior crew member identifies a threat that the other pilot has not recognised.

The process of addressing disagreement within a crew through open communication, active listening and focus on the problem rather than the person, so that the safest course of action is chosen.

A framework in which crews anticipate threats, trap or manage errors before they escalate, and avoid undesired aircraft states, supported by briefing, monitoring and cross-checking.

Written, approved instructions that prescribe how tasks are performed, providing a common baseline that reduces variability, supports coordination and allows deviations to be recognised and reported.

A structured list of actions or items used to verify that critical steps have been completed, typically read aloud and confirmed by another crew member to guard against omission and memory failure.

A safety culture in which errors and mistakes are not punished but reckless or intentional violations are, encouraging open reporting of hazards while maintaining clear accountability.

A confidential or non-punitive mechanism for personnel to report errors, near misses and hazards so that the organisation can analyse them and correct systemic weaknesses.

Reduced vigilance and monitoring of automated systems that arises when the automation performs reliably, leading crews to miss changes in mode or aircraft state.

A situation in which the crew misunderstands which automation mode is active or what the system will do next, often because of inadequate feedback from the human-machine interface.

The design of displays, controls, warnings and software through which the crew interacts with the aircraft, determining how easily information is perceived and actions are taken.

The sequence by which sensory input is perceived, attended to, interpreted, stored and acted upon, with limited capacity at each stage making bottlenecks and errors likely under high demand.

The limited capacity to select and concentrate on relevant information while suppressing distractions; it can be divided between tasks but degrades when demand is high or arousal is extreme.

The storage and retrieval of information, divided into sensory, working and long-term memory; working memory is short and easily overloaded, which is why checklists and written procedures are used.