Aviation Psychology and Human Factors

Air Regulations · Chapter 24 · DGCA CPL and ATPL

How your mind takes in, holds and acts on information, and the limits of memory, attention, stress and sleep that cause most pilot errors.

Remember

Short-term (working) memory holds 7 plus or minus 2 items for about 10 to 20 seconds without rehearsal.
Startle disrupts a skilled motor task for 5 to 10 seconds.
Automation relocates error rather than removing it, and swaps physical workload for monitoring workload.
Body temperature is lowest around 04:30 and highest around 19:00; the free-running body clock is about 25 hours.
Eastbound resynchronisation is about 50% slower than westbound; sleep inertia can last up to 20 minutes after waking.

What limits a pilot's mind?

Mind map

Four groups of limits behind most human error. Tap a box with + to open it.

The pilot's mind four kinds of limit Aviation psychology studies how pilots behave, feel and think at the controls, to understand and predict their actions and improve safety, efficiency and comfort.
- Attention a limited resource Directing and focusing mental resources on one thing. Attention is limited: what is used for one thing cannot be used for something else.
  - Selective filters for the task Samples inputs to decide what is relevant.
  - Divided time-shares between tasks Sharing limited resources lowers performance on each task.
  - Cocktail party effect your name breaks through A meaningful sound breaks through noise you were ignoring.
  - Vigilance gone wrong Vigilance is the capability to stay alert above a threshold for a period of time. It fails as hypo-vigilance, hyper-vigilance or complacency.
    - Hypo-vigilance drowsy, micro-sleeps From monotony and fatigue.
    - Hyper-vigilance near-panic scanning Panic, or close to it: trying to react to every warning sign, big and small, at the same time. It often ends in decisions you regret.
    - Complacency unaware of hazards Self-satisfaction with your own performance while unaware of danger. Automation may make pilots complacent because of low workload.
- Skill motor programmes Motor programmes are behaviour sub-routines learnt by practice or repetition, held in long-term memory and carried out without conscious thought.
  - Cognitive phase high effort, low confidence The first of the three Anderson phases in developing a motor programme or skill.
  - Associative phase rules and movements join up The second Anderson phase, between the cognitive and automatic phases of developing a skill.
  - Automatic phase spare capacity Routines run without conscious thought, leaving reserves for the unexpected.
  - Startle disrupts 5 to 10 s After a fright, a practised hand skill gets back to normal in about five to ten seconds.
- Load and stress too much or too little Workload, stress and arousal. Heavy workload goes with more errors, more fatigue, and work that gets worse.
  - Workload difficulty, task count, time Set by task difficulty, number of tasks, switching between them and time available.
  - Overload funnelling, mental blocks A very high workload is felt as stress. Workload is acceptable at about 60% of crew resources; symptoms of overload include funnelled attention, mental blocking and panic.
  - Arousal inverted U Optimum arousal is lower for complex tasks. See the curve lesson.
  - Life stress points Holmes-Rahe scale A scheme that totals points for life events to indicate life stress. Treat it with caution because individuals vary widely.
    - Under 60 free of life stress A cumulative life stress score under 60 means free of life stress.
    - Over 100 serious life stress Death of a spouse 100, divorce 73, loss of job 47.
- Machine and health design, automation, health How automation and cockpit design shape the pilot's work, and how mental health problems can threaten flight safety.
  - Automation moves error, does not remove it Jobs done or controlled by machines that run themselves. It is meant to cut errors and workload, but often gives the pilot a different, harder job: watching the machine.
    - Peripheralisation The pilot moves from direct control to managing a system.
    - Workload paradox less physical, more mental Automation reduced manual workload, but mental workload has not fallen by the same amount and may even have increased.
    - Error relocated, not removed Automation is brought in to reduce human error, but the potential for error is often simply moved elsewhere.
    - Should be predictable, error-tolerant Accountable, predictable, error-resistant and error-tolerant.
  - Cockpit design fits the central 90% If equipment can be operated wrongly, sooner or later it will be (Murphy's law). Standardization is the most important design requirement.
    - Central 90% of pilots 5th to 95th percentile A cockpit cannot fit both the shortest and the tallest people, so it is built for the middle 90% of body sizes.
    - Design eye position The cockpit is designed around one fixed point for the pilot's eye; once that point is fixed, the rest of the cockpit is sized from it.
    - Five-point harness plus negative-G strap Seats must be comfortable and adjust to fit the pilot, who is strapped in with a five-point harness that includes a strap against negative G.
    - Standard T layout attitude in the centre The attitude indicator is in the middle, with the altimeter, airspeed indicator and heading indicator grouped round it.
  - Mental health common problems first Mental health problems among pilots and other aviation personnel may impair performance and threaten flight safety.
    - Germanwings 9525 150 killed The co-pilot locked the cockpit and flew the A320 into the Alps.
    - Licence fear stops reporting Fear of losing the licence may stop pilots discussing mental health at the medical, delaying help and prolonging recovery.
    - Target the common problems not rare psychosis Depression, anxiety and substance misuse.

Takeaway: Attention is limited, skill takes practice, load and stress cut performance, and machines and health add their own traps.

How does something you see become something you do?

Stimulus to action

Follow one stimulus through the mind, from the senses to your hands and back.

Sense UNDER 1 S Receptors detect the raw stimulus and hold it briefly.
Attend and perceive MEANING ADDED Attention captures the data and perception turns it into something meaningful.
Decide WORKING MEMORY, 10 TO 20 S The central decision maker compares the situation with what long-term memory knows.
Act MOTOR PROGRAMME Muscles carry out the chosen action.
Feedback LOOP CLOSES Senses and displays check the result against what you expected.

Memory hook: Sense, Attend, Decide, Act, Feedback.

Takeaway: Senses detect it, attention and perception give it meaning, working memory decides, motor programmes act, and feedback starts the loop again.

How does information flow through the mind?

The model

Left to right: senses to long-term memory. Red boxes are where information is lost. Tap each number.

This lesson is part of the Exam-Ready plan. See plans

Which memory is holding it?

Which memory?

Read each case and press the stamp that applies.

This lesson is part of the Core plan. See plans

How do we learn and remember?

Learning

Five ways to learn and hold on to it. Tap + to open each.

This lesson is part of the Exam-Ready plan. See plans

What are the 8 steps of a good decision?

Eight steps

Fly the steps in order. Then the loop starts again.

This lesson is part of the Exam-Ready plan. See plans

Which trap is this?

Sort the traps

Tap a chip, then the bucket it belongs to.

This lesson is part of the Exam-Ready plan. See plans

What shapes how crews work with people and machines?

Crew and automation

Personality, culture, command, listening and automation. Tap + to open each.

This lesson is part of the Exam-Ready plan. See plans

What makes a cockpit easy to use?

Cockpit design

A panel, its levers and a side view of the pilot. Tap each number.

This lesson is part of the Exam-Ready plan. See plans

How much stress helps, and how much hurts?

Arousal curve

Performance against arousal. The solid curve is a complex task, the dashed one a simple task.

This lesson is part of the Core plan. See plans

What happens as workload rises?

Workload ladder

Read from calm at the bottom to panic at the top. Tap a band.

This lesson is part of the Exam-Ready plan. See plans

How do you spot and manage stress and fatigue?

Stress and fatigue

What causes it, how it shows, and what to do. Tap + to open each.

This lesson is part of the Exam-Ready plan. See plans

What is your body doing at each hour?

Body clock

A 24-hour clock with midnight at the top. The shaded wedge is the melatonin night.

This lesson is part of the Core plan. See plans

How long to adjust, how busy, how long to remember?

Mind and body limits

Three views: jet lag, the workload ladder and the mind's time limits.

This lesson is part of the Exam-Ready plan. See plans

What does each stage of sleep do for you?

Sleep stages

Four NREM stages, then REM, with what each restores.

This lesson is part of the Core plan. See plans

What sets your sleep and what does losing it do?

Sleep and the clock

The clock, the hormone, the cycle and the cost. Tap + to open each.

This lesson is part of the Exam-Ready plan. See plans

Numbers to know

Numbers

The figures examiners like, in one list.

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Pairs that catch students out

Don't mix up

Read both sides, then the line that tells them apart.

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Test yourself

Ten questions from this chapter.

This lesson is part of the Core plan. See plans