CPL Human Factors key terms

A shortage of oxygen reaching body tissues, causing impaired judgement, euphoria, and loss of consciousness. In aviation it most often results from altitude exposure without adequate oxygen supply.

The period after loss of oxygen supply during which a pilot can still take corrective action. It shortens rapidly as altitude increases and is reduced by exertion or cold.

Rapid or deep breathing that lowers blood carbon dioxide, producing dizziness, tingling, and visual disturbance. Symptoms resemble hypoxia, so the safe response is to assume hypoxia first and use oxygen.

A mistaken perception of aircraft attitude or motion relative to the earth, usually when visual references are poor. It arises because the inner ear cannot reliably sense sustained motion.

The balance organs of the inner ear, comprising semicircular canals sensing rotation and otolith organs sensing gravity and linear acceleration. They give misleading signals in sustained turns or accelerated flight.

A false sensation of pitch caused by linear acceleration or deceleration. Acceleration in level flight can feel like a climb, prompting an unnecessary nose-down input with dangerous results at low altitude.

The body's sense of pressure, touch, and position from skin, muscles, and joints. It helps a pilot feel g-forces and seat pressure but can reinforce false attitude impressions when visual cues are absent.

A false sensation of turning or of stopping a turn, caused by the semicircular canals adapting to sustained rotation. It commonly appears after rolling out of a prolonged turn or during recovery from a spin.

A false sensation of banking when the aircraft is actually level, often after a gradual roll into a turn and then a prompt correction. The pilot may lean toward the perceived vertical and misjudge attitude.

A visual illusion on night approaches over dark terrain where few ground lights exist, making the aircraft appear higher than it is. It typically leads to a low approach and undershoot.

A misleading interpretation of what the eyes see, such as a runway sloping upward or appearing narrower than reality. It causes incorrect height or glidepath judgements during approach and landing.

Misperceptions of runway slope, width, or surrounding terrain that distort the pilot's sense of height and sink rate. A narrower-than-expected runway often produces a low, flat approach.

An illusion in which a single stationary light in a dark sky appears to move, because the eye lacks a fixed reference. It can lead a pilot to mistake a star or distant light for another aircraft.

A condition in which more information arrives than a person can process, causing missed cues and slowed decisions. It is common in high-workload phases such as approach or emergency handling.

The process by which the brain interprets sensory information to build a meaningful picture of the environment. It is selective and shaped by expectation, which is why pilots can miss unexpected cues.

The limited capacity to focus mental resources on particular information while ignoring other inputs. It can be divided, selective, or captured involuntarily, and it narrows under stress.

A pilot's accurate understanding of what is happening now and what is likely next, in the aircraft and its environment. It has three levels: perceiving, comprehending, and projecting.

A breakdown in a pilot's grasp of current and future flight state, often from fixation, distraction, or fatigue. Warning signs include unexplained deviations and confusion about recent events.

The mental and physical effort needed to meet task demands in a given time. When demand exceeds capacity, performance degrades, errors rise, and tasks may be shed.

A state of reduced physical and mental capability caused by prolonged effort, insufficient sleep, or disrupted circadian rhythm. It slows reactions, impairs judgement, and increases error rates.

The body's roughly 24-hour internal cycle that governs alertness, temperature, and sleep. Flying across time zones or at night can desynchronise it, producing low alertness at critical times.

A temporary disruption of sleep and alertness after rapid travel across time zones. The body's internal clock lags behind local time, causing poor performance until it adjusts.

A response to demands or threats that raises arousal and can improve or degrade performance. Beyond an optimal level it narrows attention, increases errors, and may cause paralysis or panic.

A self-satisfied state of low vigilance arising when things go smoothly or when a pilot assumes a situation is safe. It leads to skipped checks and late detection of developing problems.

Prolonged attention on one task or instrument while other important information is ignored. It is a common precursor to loss of situation awareness and to unstabilised approaches.

Any internal or external event that pulls attention away from the primary task. Interruptions during checklists or taxiing are a frequent source of errors and omissions.

The process of choosing a course of action from available options, ideally by gathering information, weighing alternatives, and committing to a plan. It degrades under stress, fatigue, and time pressure.

The tendency to interpret ambiguous information as matching what one expects to see. It can cause a pilot to misread an instrument or accept a wrong clearance because it was anticipated.

The tendency to search for and favour information that supports an existing belief while ignoring contrary evidence. It can delay recognition of a developing emergency.

Five risk-prone attitudes identified in aviation safety training: anti-authority, impulsivity, invulnerability, macho, and resignation. Each has a matching antidote that pilots can apply.

Training and practices that make effective use of all available resources, including crew, equipment, and information, to improve safety. It covers communication, leadership, teamwork, and decision making.

The willingness to state concerns clearly and persistently when safety is at risk, even to a more senior person. It balances respect for authority with the duty to speak up.

The perceived difference in power or expertise between a leader and team members. A steep gradient can discourage junior crew from challenging errors; a flat one can blur command.

The exchange of information between people through speech, writing, and behaviour. In aviation, standard phraseology and readback reduce misunderstanding, especially under high workload.

An action or omission by a person that deviates from intended or required behaviour and contributes to an undesired outcome. It is normal and inevitable, so systems should be designed to tolerate it.

A sequence of linked mistakes and conditions that, if unbroken, leads to an accident. Breaking any single link, such as by cross-checking, can prevent the outcome.

A framework in which crews anticipate threats, detect and manage errors, and avoid undesired aircraft states. It treats error as expected and focuses on trapping it before harm occurs.

Forced delivery of oxygen at positive pressure to keep blood oxygenated at very high altitude. It requires active exhalation and correct mask technique, and failure to manage it causes rapid hypoxia.