AVIATION PSYCHOLOGY & HUMAN FACTORS

DGCA CPL / ATPL Study Notes
Chapter 25 — Source pages 615 – 652
Compiled by Capt. Pankaj Pahil

Table of Contents

  1. Introduction to Aviation Psychology
  2. Human Error & Human Reliability
  3. Workload
  4. Information Processing — Functional Model
  5. Types of Memory & Sensory Memories
  6. Anticipation & Perception
  7. Attention
  8. Vigilance & Complacency
  9. Motor Programmes (Skills) — Anderson Model
  10. Reflexes, Reaction Time & Startle
  11. Quantitative Overload & Human Reliability
  12. Short Term & Long Term Memory
  13. Learning, Retention & Motivation
  14. Response, Cognition & Hallucination
  15. Judgment & Decision Making
  16. Personality, Attitude & Situational Awareness
  17. Mechanics of Decision Making
  18. Communication & Team Work
  19. Automation
  20. Human Characteristics & Cockpit Design
  21. Hardware — Displays & Controls
  22. Stress, Tolerance, Fatigue & Arousal
  23. Body Rhythm Disturbance — Circadian Cycle
  24. Sleep — NREM & REM
  25. Mental Health Problems & Disorders
  26. Master Reference Tables & Mnemonics

1. Introduction to Aviation Psychology

What this section covers Definition of aviation psychology, its aims, and how its tools support flight safety and efficiency.

Aviation Psychology is a specialty in applied psychology that focuses on understanding human behaviour, emotions and mental states as they relate to the operation and control of aviation systems and their influence on the safety and efficiency of flight.

The aim of aviation psychology is to understand and to predict the behaviour of individuals in an aviation environment. Its study is aimed at improving safety, efficiency and comfort.

Practitioners of aviation psychology bring the tools and techniques of psychology to bear in order to describe, predict, understand and influence the aviation community to achieve those aims.

Exam Tip — The Four Action Verbs Remember the four practitioner verbs: D – P – U – IDescribe, Predict, Understand, Influence.

2. Human Error & Human Reliability

What this section covers The inevitability of human error and the four areas where pilot errors usually originate.

It has long been accepted that human errors are inevitable. The majority of pilot-related errors are considered to be failures of:

This does not mean that the frequency of error cannot be reduced, or that the effects cannot be avoided or mitigated.

Golden Maxim — "Superior Pilot" "A superior pilot uses his superior judgment to avoid situations that would require his superior skills."
flowchart LR
  A[Pilot Error
Origins] --> B[Interpersonal Skills] A --> C[Communications] A --> D[Decision-Making] A --> E[Leadership] B --> F[Mitigation:
Superior Judgment] C --> F D --> F E --> F F --> G[Safe Flight Outcome]

3. Workload

What this section covers Cognitive (mental) workload definition, the four task factors that drive it, indirect factors and observable symptoms.

Workload = the amount of mental effort needed (and expended) to process information. Here we discuss cognitive (mental) workload, as opposed to physical workload. Workload is linked to almost all other areas within cognition and performance, particularly attention, vigilance, fatigue, decision-making and multi-tasking.

Effects of High Workload High workload is associated with increased errors, fatigue, task degradation and poor performance.

3.1 Four General Task Factors Affecting Workload

  1. 'Difficulty' of the task
  2. Number of tasks running in parallel (concurrently)
  3. Number of tasks in series (switching from task to task)
  4. The time available for the task (speed of task)

Indirect factors also play a role: duration of task, fatigue and level of arousal.

3.2 Symptoms of Increasing Workload

The area that deals with all such activity is called the working memory ('Information Processing').

Exam Tip — Workload Drivers Mnemonic "DPST"Difficulty, Parallel tasks, Series switching, Time available.

4. Information Processing — A Functional Model

What this section covers How sensory inputs are converted into reasoned actions through five mental stages, and the central role of working memory.

We receive information from the world around us through our senses: sight, hearing, touch, smell and taste. The "Gestalt laws" formulate basic principles governing how objects are mentally organised and perceived.

4.1 The Five Stages of Reasoning

  1. Detection
  2. Perception
  3. Decision Making
  4. Action (responses are selected and executed)
  5. Feedback
flowchart LR
  S[Sensory Input
Sight / Hearing / Touch /
Smell / Taste] --> D[1. Detection] D --> P[2. Perception] P --> DM[3. Decision Making
Working Memory] DM --> A[4. Action
Response Executed] A --> F[5. Feedback] F -.alters action.-> DM LTM[(Long-Term Memory)] <--> DM STM[(Short-Term Memory)] <--> DM

4.2 The Brain — Central Decision Maker & Response Selection

Once information has been perceived a decision must be made as to the response. Information is continuously entered into and withdrawn from both long-term and short-term memories to assist the decision process. The decision involves input, processing, actions and feedback. The information comes from many sources and requires conscious processing in working memory. A problem at any stage of information processing could affect the outcome.

To carry out multi-tasks we must learn skills through Motor Programmes.

4.3 Stimuli

The senses provide stimuli to our brain which has the ability to retain them for a short time, from the time they arrive. We may not have the processing capacity to deal with them all.

Exam Tip — First Stage First stage in the information process = Sensory stimulation (not "Attention", not "Perception"). Detection is what follows.

5. Types of Memory & Sensory Memories

What this section covers Three memory types, key features of sensory memory, iconic memory for sight, and sensory adaptation.

5.1 The Three Types of Memory

5.2 Receptors & Sensory Memories — Key Features

The sensory stores for sight and sound are the most important, and knowledge of these is necessary.

5.3 Information Processing Model — Diagrammatic View

Sensory Input SENSORY MEMORY Attention Pattern Recog. Decay SHORT-TERM MEMORY (10–20 s) Rehearsal Displacement / Decay Encoding Retrieval LONG-TERM MEMORY Interference / Lost Cues L O S S

5.4 Sensory Memory for Sight — Iconic Memory

The Iconic Memory is the visual sensory store. It only lasts for between 0.5 and 1 second.

70–80 % of the information processed by humans is received through the visual channel.

5.5 Sensory Adaptation (Habituation)

All senses adapt, either partially or completely, to their stimuli after a period of time.

Exam Tip — Sensory Memory Values Iconic memory = 0.5–1 second. Visual channel carries 70–80 % of all received information.

6. Anticipation & Perception

What this section covers How sensory input becomes meaning, the role of expectation, mental models and the concept of funneled perception.

6.1 Perception

Perception involves the conversion of the sensory information received into a meaningful structure.

Sensory information that we expect to receive is more easily perceived and integrated when it actually occurs, compared with totally unexpected information.

"We can 'perceive' only that which we can 'conceive', but we perceive only a fraction of the information reaching our senses at any moment."

The process of perception is greatly assisted by our ability to form mental and three-dimensional visual models.

6.2 Funneled Perception

Perception of a situation can differ depending upon the starting point of an observer.

Hazard — Confirmation Bias / Funneling In an abnormal situation, if a pilot has an apparently correct explanation for the problem, the chance that he/she now ignores or devalues other relevant information not fitting into the mental picture is increasing. Stay open-minded; verify, don't rationalize.

7. Attention

What this section covers Definition, the two types of attention, why an attention mechanism is required, the cocktail party effect and the dangers of attention mismanagement.

Attention is the process of directing and focusing psychological resources to enhance perception, performance and mental experience. To pay attention to something is to concentrate on it — a stimulus, threat, decision or calculation. Critically, attention is limited; if some attention is being used for one thing, it cannot be used for something else.

7.1 Types of Attention

  1. Selective Attention — inputs are sampled continually to decide their relevance to the present task at hand.
  2. Divided Attention — when our central decision-making channel can time-share between a number of tasks, executing several mental activities at almost the same time (e.g. switching attention from outside the aircraft to the airspeed indicator and monitoring the progress of a motor programme such as flying or taxiing on a relatively subconscious level, while making a radio call at the same time).

The human brain has different reservoirs of resources for information-gathering, information-processing, or the action phase.

7.2 Lack of Attention

The major danger for pilots is the poor management of attention.

7.3 Attention Mechanism — Why It Is Required

Because of two potentially limiting stages in processing information:

  1. There is a limit to the number of items held or maintained in short-term memory (working memory).
  2. Our channel capacity is limited.

7.4 Choice of Item

Attention is the deliberate devotion of cognitive resources to a specific item. Although attention can move very quickly from item to item, it can only deal with one at a time — so the pilot must consciously prioritize.

7.5 The Cocktail Party Effect

With many conversations occurring all around, one conversation can suddenly break through to attention because a word or phrase was particularly meaningful — the classic example is a person hearing their own name mentioned in another conversation that they were not paying attention to.

Exam Tip — Cocktail Party Effect Defined as the ability to pick up relevant information unintentionally. It demonstrates that the brain monitors even unattended channels for personally significant cues.

8. Vigilance & Complacency

What this section covers Definition of vigilance, the three states (hypo, optimum, hyper), causes and signs, plus the trap of complacency in automated cockpits.

Vigilance = the capability to be sensitive to potential changes in one's environment, i.e. the capability to reach a level of alertness above a threshold for a certain period of time — rather than the state of alertness itself.

8.1 Hypo (Low) Vigilance

Mainly due to the monotony of the task, tiredness, the need for sleep and a lack of stimulation. It may occur at any moment of the flight. Decrease in sensory perception and sensation of muscular heaviness are indications of low vigilance.

A state of high fatigue is liable to cause phases of drowsiness and hypo-vigilance, which result in a reduction of performance and unconscious phases of micro-sleep.

SOP — Managing Hypo-Vigilance Healthy food and organising periods of rest during the flight can mitigate the effects of low vigilance.

8.2 Hyper Vigilance

In its most acute forms, an extremely agitated state of panic or near panic. Characterised by indiscriminate attention to all sorts of minor and major threat cues, as the person frantically searches for means of escaping the anticipated danger.

Hazard — Hyper Vigilance Hyper vigilance is a state of panic that often results in regrettable decision-making.

8.3 Optimum Vigilance

Lies somewhere between hypo and hyper vigilance.

8.4 Complacency

A state of self-satisfaction with one's own performance coupled with an unawareness of danger, trouble or controversy.

Hazard — Complacency Complacency is extremely dangerous in aviation. You get so used to things being done the same way that you become less vigilant to hazards in your surroundings. Automation may make pilots complacent due to low workload.
flowchart LR
  A[Vigilance Spectrum]
  A --> H[HYPO
Drowsiness, Micro-sleep
Cause: Monotony, Fatigue] A --> O[OPTIMUM
Best Performance] A --> Y[HYPER
Panic, Indiscriminate Attention] H -.->|risk| C[Complacency
Low workload, Automation] Y -.->|risk| R[Regrettable Decisions]

9. Motor Programmes (Skills) — Anderson Model

What this section covers What motor programmes are, the three phases of skill development per the Anderson model, and how skill enables resource management.

Motor Programmes, or "Skills", are behavioural sub-routines which are learnt by practice and/or repetition and are held within the Long-Term Memory. They can be carried out without conscious thought.

In the initial phase of flight training the pilot is competent enough to fly the aircraft at this stage but does neither have a great deal of confidence in his/her abilities nor in the whole system.

What Makes a Pilot "Skilled" A pilot is skilled when he trains or practices regularly, knows how to manage himself/herself and knows how to keep resources in reserve for coping with the unexpected.

9.1 Anderson Model — Three Phases

  1. The Cognitive Phase
  2. The Associative Phase
  3. The Automatic (Autonomous) Phase
flowchart LR
  C[a) Cognitive Phase
Conscious effort,
understanding rules] --> AS[b) Associative Phase
Refinement,
fewer errors] AS --> AU[c) Automatic Phase
Subconscious execution,
resources freed for new tasks] AU --> SKILL[Stored as Motor Programme
in Long-Term Memory]
Exam Tip — "Flying a coordinated turn is …" Skill-based behaviour — not attention-based, not experience-based. It draws from procedural memory in the LTM.

10. Reflexes, Reaction Time, Surprise & Startle

What this section covers Reflex types, what reaction time depends on, and the operational impact of the startle reflex on pilots.

Reflexes occur with little or no involvement of the central nervous system.

10.1 Reaction Time

There is a delay between detection, stimulus and muscle contraction called reaction time. Reaction time depends on the type of reflex action being used.

10.2 Three Types of Reflex Actions

TypeDescriptionExample
UnconditionedInstinctive natural reflexesBlinking
ConditionedReflexes that may be learnedFoot-on-rudder on swing
TrainedReflexes that may be increased by repeated practiceStall recovery inputs

10.3 Surprise and Startle

The startle reflex is a reflex-like event that blinks the eyes and causes a whole-body 'jerk' to occur (similar to that sometimes caused in sleep). The reflex has a relatively basic neural pathway from the sense organ. Many things can cause (or contribute to) a startle reflex:

There is little evidence that a startle reflex alone creates much of a sustained or lasting impact on cognitive functions, although there are some minor and short-lived physiological changes such as raised heart rate.

Key Value — Startle Recovery A skilled motor task will be momentarily disrupted by a startle reflex but return to normal within 5 to 10 seconds.

10.4 Effects on Pilots

The main effects of the pure startle reflex on pilots are:

These happen almost immediately and can be quickly dealt with if the cause is found to be non-threatening.

Hazard — Fear Potentiates Startle A perception of fear can cause a startle reflex to be potentiated (more pronounced) should it occur, and attention to become more focused. In a state of fear, very little is required to trigger a full 'fight or flight' response.

11. Quantitative Overload & Human Reliability

What this section covers When workload is acceptable, what overload looks like, error rates with practice, and the cumulative nature of errors.

Quantitative Overload — a very high workload can be interpreted as 'Stress'.

SOP — Acceptable Workload Workload may be said to be acceptable if it requires about 60 % of the crew resources, depends on the pilot's expertise and corresponds to the amount of resources available.

11.1 Most Common Symptoms of Overload

11.2 Human Reliability

The rate of human error during simple and repetitive tasks might be expected to be 1 in 100, but after practice, a rate of 1 in 1,000 could be achieved.

Definition — Human Reliability The individual functioning in the manner in which he or she is supposed to function.

11.3 Error Generation

Errors tend to be cumulative. One slip rarely stays isolated — it sets up the next.

Worked Example — Human Error Rate A pilot performs 200 routine pre-flight checks per week.
• Before practice (1 in 100): expected errors ≈ 200 ÷ 100 = 2 errors / week.
• After practice (1 in 1,000): expected errors ≈ 200 ÷ 1,000 = 0.2 errors / week (i.e., about 1 every 5 weeks).
Practice yields a 10-fold reduction in error rate, but never reaches zero — hence the value of cross-checking and SOPs.

12. Short-Term & Long-Term Memory

What this section covers Duration and capacity of short-term memory, methods to expand it, the three subtypes of long-term memory and its capacity characteristics.

12.1 Short-Term Memory (Working Memory) — 10 to 20 Seconds

Short-term memory enables information to be retained for a short period of time. That information will be lost in 10 to 20 seconds unless it is actively rehearsed and deliberately placed in our long-term memory.

Auditory information is considered easier to retain than visual information as it is easier to rehearse sounds than data in a visual form.

12.2 Limitations of Short-Term Memory

The capacity of our short-term memory is limited. The maximum number of unrelated items which can be maintained in the short-term memory is about 7 ± 2. Once this limit is exceeded one or more of the items are likely to be lost or transposed.

12.3 Methods of Increasing Short-Term Memory

MethodDescription
ChunkingBreaking items to be remembered into small pieces and remembering them one at a time.
AssociationUsed to remember spoken lists of items. A wild and bizarre association is imagined and attached to each item on the list.
Worked Example — Chunking an ATC Clearance Raw clearance string: "VTBL VTBS RWY01L SQK4732 ALT FL310 HDG270" — 7+ unrelated tokens, near STM limit.
Chunked: "VT-BL → VT-BS" (route), "RWY 01L" (departure), "4732" (squawk), "FL310" (level), "HDG 270" (heading) = 5 chunks — comfortably within 7 ± 2.

12.4 Long-Term Memory — Unlimited Time Period

It is believed that information is stored in the Long-Term Memory for an unlimited time period, although frequently there may be retrieval problems.

12.5 Three Subtypes of Long-Term Memory

TypeDefinitionExample
Semantic MemoryStores general knowledge of the worldKnowing that "QNH is altimeter setting"
Episodic MemoryMemory of events or 'episodes' in our lifeRecalling your first solo flight
Procedural MemorySkills are included within the make-up of the LTMExecuting a coordinated turn
Exam Tip — Memory Quick Facts • STM duration = 10–20 seconds, capacity = 7 ± 2 items.
• LTM capacity = unlimited, but retrieval problems may exist.
• Motor programmes live in LTM (Procedural), not STM.

13. Learning, Retention & Motivation

What this section covers Types of learning, methods to retain information, and the role and sources of motivation.

13.1 The Learning Process

Learning is an internal process which allows the mental acquisition and retention of data. Types include:

Insight

The data is intellectually and cognitively understood and is retained. Observational Learning / Imitation — data from an outside source is replicated. Experience — learning from our mistakes.

Skill Learning

Involves motivation, attention, observation, much practice and corrective feedback.

13.2 Retention of Information

Retention can be increased by:

  1. Mnemonics — the practice of improving or helping the memory, or the systems used to achieve this.
  2. Memory Training

13.3 Motivation

Motivation is the combination of a person's desire and energy directed at achieving a goal. It is the cause of action.

TypeExamples
IntrinsicSatisfaction and feelings of achievement
ExtrinsicRewards, punishment, and goal obtainment

Not all people are motivated by the same thing and over time their motivations might change.

SOP — Motivation and Performance The learning process is vastly improved with motivation, and high performance is rarely achieved without it.

14. Experience, Response, Cognition & Hallucination

What this section covers How experience shapes us, response characteristics with age, error of commission, response times, cognition in flight, and hallucinations.

14.1 Experience

We all have the ability to learn from our experiences and mistakes, and from those of others.

14.2 Response

Any response will cause a detectable change which, in turn, will be noted by the senses. The feedback may alter the action being taken.

14.3 Response Error (Error of Commission)

If an unexpected stimulus occurs, we will be more likely, under pressure, to make an error of commission.

14.4 Response Times

Response to reaction time is the interval between the onset of a given signal and the production of a response to that signal.

14.5 Cognition in Aviation

Cognition = the mental faculty or process of acquiring knowledge by the use of reasoning, intuition or perception. In aviation, flight puts the pilot into an environment which can distort sense organs, and the changed perspective which is experienced in flight can result in information being presented which is outside the individual's expectations.

14.6 Hallucination

A hallucination is actually a false perception characterised by a distortion of real sensory stimuli. (Not a fabrication of stimuli — the stimuli are real, but their perception is distorted.)

14.7 Workload and Limitations

Too high or too low a workload can result in degraded performance. Several types of situations may cause mental overload.

Exam Tip — Age and Response Between 20 and 60 years → responses become slower but more accurate. Experience compensates for slower reflexes.

15. Judgment & Decision Making

What this section covers Why decisions matter, how to seek advice, risk assessment fundamentals, and the dynamic nature of "good" decisions.

Making good decisions is one of the important aspects of piloting an aircraft. Good decisions can help lead to safe, successful flights, whereas bad decisions and even indecision have led to many aircraft accidents. Talk to your instructor and other pilots about different flying situations to obtain advice about what a good decision would be in a given circumstance.

When flying with another pilot, it is possible to increase the chance of a good decision being made by discussing the potential problems beforehand. If as an inexperienced pilot you are flying with someone of more experience and you see him doing something you consider to be dangerous, you should immediately question their course of action.

Best Practice — Always More to Learn A good pilot is one who always realizes there is more to learn. When making a decision a pilot will be influenced by his previous experience, the probability of an occurrence, and whether the information he is receiving matches that expected.

15.1 Risk Assessment

Risk assessment is based on:

You will have to weigh up the risk and the possible consequences of the risk in order to determine your course of action.

flowchart TD
  A[Identify Risk] --> B{Probability
of Occurrence} A --> C{Impact
if it Occurs} B --> D[Combine Probability × Impact] C --> D D --> E{Acceptable?} E -- Yes --> F[Proceed with Mitigation] E -- No --> G[Modify Plan / Don't Fly]
Remember Making good decisions is one of the most important aspects of piloting an aircraft. Good decisions can help lead to safe, successful flights, whereas bad decisions and even indecision have led to many aircraft accidents. Always strive to make good decisions.

16. Personality, Attitude & Situational Awareness

What this section covers Desirable pilot traits, the meaning of being Pilot-in-Command, factors that destroy situational awareness, and how to maintain it.

16.1 Personality, Attitude and Behaviour

Someone who is too introverted or anxious may not make a good pilot. Examples of desirable characteristics in a pilot are:

As captain of an aircraft, you will need to show good leadership skills.

SOP — Being Pilot-in-Command While acting as pilot-in-command you should ensure that you stay in command — you should be properly organized and prepared.

16.2 Situational Awareness

A good leader displays good situational awareness and accurately assesses his own performance. The following factors can interfere with accurate situational awareness:

  1. Stress
  2. Boredom
  3. Fatigue
  4. Emotional disturbance
  5. Poor communication
  6. Interruptions
Maintaining Good SA — SOP In order to maintain good situational awareness, gather as much information as possible. Do not rush into making a decision. Make sure you consider all the options. Do not make the mistake of seeing something that is not really there just because you want it to be there.
Exam Tip — SA Interference Mnemonic "SBF-EPI"Stress, Boredom, Fatigue, Emotional disturbance, Poor communication, Interruptions.

17. Mechanics of Decision Making

What this section covers The seven-step decision cycle and the dynamic nature of decisions in flight.

Pilots operate in a dynamic and constantly changing environment. A good decision reached a minute ago will not necessarily be the same good decision in two minutes' time.

17.1 The Seven Steps

  1. Recognize and identify the problem — have a clear definition of what needs addressing.
  2. Consider the nature of the problem — type of issue, why it needs a decision, hoped-for results.
  3. Analyze or research the problem — gather all information so informed choices can be made.
  4. Develop a list of possible solutions — list decisions and their consequences.
  5. Select the best alternative — choose the best solution for the situation.
  6. Execute the best choice — taking action is often the hardest part.
  7. Follow up and communication — keep the process going with constant communication; Feedback determines the overall success of and reaction to the decision.
flowchart LR
  S1[1. Recognize
& Identify] --> S2[2. Consider
Nature] S2 --> S3[3. Analyze
/ Research] S3 --> S4[4. List Possible
Solutions] S4 --> S5[5. Select Best
Alternative] S5 --> S6[6. Execute
Best Choice] S6 --> S7[7. Follow Up &
Communicate] S7 --> FB[Feedback] FB -.re-evaluate.-> S1
Exam Tip — Dynamic Decisions A good decision a minute ago may not be a good decision two minutes from now. Re-evaluate continuously.

18. Communication & Team Work

What this section covers Why communication matters, attitudes that destroy teamwork, and the danger of "expectation".

When piloting an aircraft — whether with a passenger, another pilot or an instructor — good verbal communication will help the flight go more smoothly and contribute to flight safety.

Concise and unambiguous communication is essential to the safe conduct of air traffic.

18.1 Barriers to Communication & Team Work

Several things can be done by team leaders to facilitate good teamwork. In the end, it is the team leader who takes the decisions on behalf of the team.

Hazardous Attitudes — Barriers Some of the barriers to communication and teamwork are:

18.2 Expectation

Hazard — Expectation Bias Do not assume you have heard what you are expecting to hear. Actively listen. Clear, concise and unambiguous communication is essential to the safe conduct of aviation.

19. Automation

What this section covers Definition and evolution of automation, the mismatch between automation and the human element, and qualities of human-centred automation.

Automation refers to a system or method in which many of the processes of production are automatically performed or controlled by self-operating machines, electronic devices, etc.

Through microprocessor technology, navigational tasks and aircraft system management have been automated, making the flight crew more peripheral to the actual operation of the aircraft. Pilots who at one time had direct authority over all aspects of aircraft control and management have now become responsible for the management of complex hardware and software interfaces.

These technological advances have given rise to new forms of error. Automation is almost always introduced with the expectation of reducing human error and workload, but what frequently happens is that the potential for error is simply relocated. More often than not, automation does not replace people in systems; rather, it places the person in a different, and in many cases, more demanding role.

19.1 Definition of Automation

"The technique of controlling an apparatus, a process or a system by means of electronic and/or mechanical devices that replaces the human organism in the sensing, decision-making and deliberate output."

19.2 Evolution of Transport Aircraft Automation

PILOT CONTROLS AIRCRAFT Gen 1 PILOT AUTOPILOT CONTROLS AIRCRAFT Gen 2 PILOT CONTROLLER AUTOPILOT CONTROLS AIRCRAFT NAVAIDS Gen 3 PILOT CDU FMS CONTROLLER AUTOPILOT CONTROL SYSTEMS PMS NAVAIDS INS CADC Gen 4 Increasing peripheralization of the pilot →

19.3 Mismatch Between Automation and the Human Element

Nevertheless, a few accidents point to a mismatch between automation and the human element. Studies identified nine categories to focus on:

  1. Situational awareness
  2. Automation complacency
  3. Automation intimidation
  4. Captain's command authority
  5. Crew interface design
  6. Pilot selection
  7. Training and procedures
  8. The role of pilots in automated aircraft
  9. (Studies concluded scope for improvement in fields like: human capabilities and limitations, ergonomics, cognitive suitability and instrument standardization.)
Hazard — Automation Side-Effects Although cockpit automation may provide pilots with more time to think, it may encourage pilots to reinvest only some of this mental free time in flight-related thoughts. While manual workload has reduced, mental workload has not been reduced by the same amount — in fact it may have been increased. Automation may not always reduce workload in phases of flight in which it is usually high (e.g. arrivals/landings at busy terminals). High cockpit automation may reduce pilot attention with the consequence of 'being out of the loop'.
Hazard — Reliability ≠ Safety All forms of automated assistance for the human operator must be highly reliable, but this may also induce complacency. Human expertise may gradually be lost and if the machine fails, the human operator may accept an inappropriate solution or become unable to formulate a satisfactory alternative.

19.4 Qualities of Human-Centred Automation

Human-centred automation should possess these qualities in proper measure:

Best Practice — Complementary, Not Alternative Pilots, computers and machines are not alternatives, but complementary factors in ensuring flight safety. Achieving the correct balance benefits safety. Automation has undeniably led to an improvement in flight safety.

20. Human Characteristics & Cockpit Design

What this section covers Personality types, cultural differences, anthropometry, eye datum, cockpit seats and the design considerations driving them.

20.1 Personality

Personality involves two major factors:

Extroverts are said to be impulsive and sociable; introverts are more withdrawn and cautious.

A low-neuroticism personality is one of an emotionally stable person, whereas a high-neuroticism person will worry and get upset easily.

Trait vs State Anxiety High neuroticism = high trait anxiety (a personal trait of that person). As opposed to state anxiety, which is a transient state of anxiety present in anyone at any time.

20.2 Cultural Differences

The way people behave, think and interact with each other generally — as well as what motivates them — will be partly a factor of their national and cultural background. One culture may value subordinates speaking up, whereas another culture may value subordinates who obey their superiors unquestioningly. The latter might perceive a subordinate who points out a concern as being impolite, aggressive or disruptive.

20.3 Competencies

The main area where personality and background culture are important is interpersonal interaction. In terms of competencies, this means communication, leadership and teamwork — crew interactions or interactions with outside agencies such as air traffic control.

20.4 Design Considerations

The following human characteristics must be taken into account in the design of aviation systems:

20.5 Hardware, Design of Flight Decks, Size & Anthropometry

Murphy's Law "If equipment is designed in such a way that it can be operated wrongly, then sooner or later, it will be."

Therefore a great deal of attention is required to design the equipment. The most important requirement in the design of both displays and controls is STANDARDIZATION.

20.6 Anthropometry

This is the study of human measurement. The information is grouped into:

It is not practical to design a cockpit for both the very short and the very tall individual. Those in the central 90 % of size distribution will be catered for. Normally the design of aircraft uses measurements taken from the entire population disregarding both the 5 % lowest and the 5 % highest.

20.7 Eye Datum

Cockpit space must be designed around a defined position of the pilot's eye. This may be called the Eye Datum, the Design Eye Position or the Reference Eye Point.

PositionEffect
Too highPoor view of instruments, obstructed high view, good downward view
Just rightOptimum view of outside and instruments
Too lowGood view of instruments but poor forward and downward view

Once the design eye position has been set, the size of the cockpit can be established.

20.8 Design of Cockpit Seats

It is of the utmost importance that the seating is comfortable and adjustable to the individual pilot's size and shape. Pilots should adjust their seats to establish a comfortable position giving full control movement, with optimum instrument scan and outside visibility. This position should be used for all phases of the flight.

SOP — Restraint Restraint should be provided by a 5-point harness with a negative 'G' strap.

21. Hardware — Displays & Controls

What this section covers Digital vs analogue display selection, the standard "T" layout, three-pointer altimeter pitfalls, and the eight basic considerations for control design.

21.1 Presentation Requirements

Information TypeBest Display
Purely quantitative informationDigital
Qualitative informationAnalogue (more easily assessed)

21.2 Conventional Analogue Standard 'T' Display

A standard 'T' layout has the artificial horizon / attitude indicator at the centre with the altimeter, airspeed indicator and direction indicator grouped around it. Digital Display and the Compass. The conventional analogue type of compass card gives a better picture of the aircraft orientation than would a digital readout.

21.3 Combination or Analogue and Digital Displays

In some instances, both digital information and analogue information can be combined in a single instrument.

Hazard — Three Pointer Altimeter The three-pointer altimeter can easily be misread and produces significantly more reading errors than the single-pointer altimeter.

21.4 Hardware, Controls — Basic Considerations

PrincipleDescription
StandardizationControl of location and sense of use from one aircraft to another should be standardized.
Frequency of UseControls used frequently or for protracted periods should be located so that they do not require the pilot to adopt an awkward or fatiguing position.
Sequence of UseControls that should normally be used in a given order should be laid out so that the sequence of use is represented in that layout.
ImportanceImportant controls must be located in easily reached and unobstructed positions.
Visual/Tactile DissimilaritySwitches and knobs that control different systems or functions should look and feel different from each other.
SymbolismControls, if possible, should be designed to contain some reference to their function.
Simultaneous UseControls which may require simultaneous use should be located to enable this to take place.
WarningsAll warnings should be 'attention getting' without being startling. The most conspicuous visual warnings rely on head and gaze orientation.
ATTITUDE ASI Airspeed ALT Altimeter DI STANDARD "T" LAYOUT Attitude Indicator at centre · ASI–ALT–DI grouped around

22. Stress Tolerance, Fatigue & Arousal — Well-Being of Operational Personnel

What this section covers Stress, arousal, fatigue, environmental tolerances, life stress scoring, stress management, and the arousal-performance relationship.

Three of the many factors which may influence the well-being of operational personnel are:

  1. Stress and fatigue
  2. Body rhythm disturbance
  3. Sleep deprivation or disturbance

Other factors affecting physiological or psychological well-being include: temperature, noise, humidity, light, vibration, workstation design and seat comfort.

22.1 Stress, Arousal and Performance

The different stress levels generated within individuals by a particular stressor will differ. A moderate level of stress may improve performance. Stress promotes an increase in physical strength rather than promoting mental performance.

22.2 The Effects of Stress

In an active, outward-going, highly trained person, too little stimulation or stress arousal will lead to the onset of boredom and even drowsiness. An introspective, under-confident person, if highly aroused, might be unable to function at all — even in circumstances that he is competent to deal with.

22.3 Stress Factors (Stressors)

Stress factors are cumulative. Stress occurs under various conditions:

SOP — Key to Reduced Workload Thorough flight planning is the key to reducing cockpit workload.

22.4 Environmental Tolerances

Temperature, pressure, humidity, noise, time of day, light and darkness can all be reflected in performance and also in well-being. Heights, enclosed spaces, and a boring or stressful working environment can also influence performance.

22.5 Managing Stress

Recognising stress, accepting it and developing a coping strategy is essential for stress management. Training and experience help to ward off stress and high levels of arousal. Successful completion of a stressful task will reduce the amount of stress experienced when a similar situation arises in the future.

SOP — Stress Self-Management To avoid stress, know your limits and fly well inside them. If you are aware that you are under stress, consider whether it would not be wiser for you to stay on the ground rather than to fly when you are not up to it. Make sure that cockpit housekeeping is of a high order and that all documents, charts and associated equipment are appropriately stored and accessible. High-quality headsets will reduce cockpit noise levels. Temperature can often be regulated using the cabin heating or ventilation system.

22.6 Life Stresses — Psychological Scoring

Pilots suffering from life stress should be aware that this can affect their concentration and performance when at the controls of an aircraft. The descending order in which the factors affect a person:

Death of spouse/child → Divorce → Marital separation → Death of a close family member → Injury / illness → Marriage → Loss of job → Retirement → Pregnancy → Sexual problems → Birth → Change of financial status → Siblings leaving home → Change of eating habits → Change of residence → Loan/debt/mortgage → Vacations → Minor violations of law.

Life EventScore
Death of a spouse or partner100
Divorce73
Marital separation65
Death of a close family member63
Personal injury or illness53
Loss of job47
Retirement45
Pregnancy40
Sexual problems40
Son or daughter leaving home29
Change of residence20
Bank loan or credit card debt17
Vacation13
Minor law violation11
Cumulative ScoreInterpretation
< 60Free of life stress
60 – 80Normal life stress
80 – 100High life stress
> 100Under serious life stress

Note: such schemes need to be treated with caution because of wide individual variability.

22.7 Indications of Stress

Stress causes: mental blocks, confusion, channelized attention, resignation, frustration, rage, deterioration in motor coordination, high pitch voice and fast speaking.

Easily Observable Indications of Stress Perspiration, flushed skin, dilated pupils and fast breathing.

22.8 Tiredness and Fatigue

Tiredness and fatigue, though related concepts, differ in their long-term physical effect on the body. To deal with normal tiredness it is sufficient to ensure that periods of activity and periods of restful sleep comply with the normal pattern for a person's age and physical condition.

Ordinary tiredness results from normal physical and/or mental exertion over a normal waking period. If a person is tired, a good night's sleep is the only requirement for that person to be fit the following morning.

Definition — Fatigue Fatigue is a very deep tiredness due to the cumulative effects of a stressful lifestyle and/or living and working environment.

Causes of Fatigue

Symptoms of Fatigue

Minimum Self-Help Program

22.9 Arousal

Arousal is a major aspect of many learning theories and is closely related to other concepts such as anxiety, attention, agitation, stress and motivation.

Arousal LevelEffect
Low ArousalIn cruise, attention can wander; information missed or misinterpreted
Optimum ArousalCentral Decision Maker at its most efficient. Lower for difficult/cognitive tasks; higher for tasks requiring endurance and persistence
High Arousal (Overload)Real danger of attention becoming narrowed
Yerkes-Dodson Curve — Arousal vs Performance Arousal Level → Performance → LOW Boredom OPTIMUM Peak Performance HIGH Attention Narrowed
Exam Tip — Stress Promotes… Stress promotes an increase in physical strength rather than mental performance. A moderate level of stress may improve performance.

23. Body Rhythm Disturbance — The Circadian Cycle

What this section covers The biological clock, the 24-hour vs 25-hour cycle, melatonin's role, jet-lag rules and re-synchronization rates.

23.1 Stimuli and Attention

Our bodies are continuously receiving stimuli through our five senses. This information is stored briefly in our sensory memory and, if we perceive it to be important, it is transferred to our short-term memory or Central Decision Maker. Some stimuli are better than others at getting our attention. We can split our attention between several different things by concentrating on them in rapid succession.

23.2 The Circadian Circle

The Circadian Circle represents our level of alertness throughout the day. Circadian rhythms are internally generated by a self-sustaining (autonomous) biological clock located in the hypothalamus, which functions as the main control centre for the autonomic nervous system by regulating sleep cycles, body temperature, appetite, etc., and acts as an endocrine gland by producing hormones. It takes into account biological elements such as body temperature, heart rate and blood pressure — which affect our level of alertness during the day.

Hazard — Circadian Lows Human performance degradation at circadian lows is one of the major challenges for the aviation industry.

23.3 24-Hour Circadian Reference

TimeBody Event
00:00Midnight
02:00Deepest sleep
04:30Lowest body temperature
06:45Sharpest rise in blood pressure
07:30Melatonin secretion stops
08:30Bowel movement likely
09:00Highest testosterone secretion
10:00High alertness
12:00Noon
14:30Best coordination
15:30Fastest reaction time
17:00Greatest cardiovascular efficiency and muscle strength
18:30Highest blood pressure
19:00Highest body temperature
21:00Melatonin secretion starts
22:30Bowel movements suppressed

As we sleep, our heart rate is lowered and hence our level of alertness is reduced. Blood pressure is also often lowered after mealtimes. Human performance declines at night when the body and mind desire rest.

23.4 Melatonin — "The Light of Night"

Melatonin is secreted from the pineal gland principally at night. The hormone is involved in sleep regulation, as well as in a number of other cyclical bodily activities and circadian rhythm in humans.

This circadian rhythm of secretion plays an important role in its hormonal activity. Melatonin is exclusively involved in signalling the 'time of day' and 'time of year' (hence considered to help both clock and calendar functions) to all tissues, and is thus considered to be the body's chronological pacemaker or 'Zeitgeber'.

23.5 Trans-Meridian Flight — Pilot Considerations

FactorValue / Rule
Free-running circadian cycle (no time cues)~ 25 hours
Cycle with normal time cues~ 24 hours
Stop-over ruleIf stop-over > 24 hours → move to new time as soon as possible
Crossing > 3–4 time zones with layover > 24 hoursKeep in swing with rhythm of the departure country for as long as possible; maintain regular living patterns
Re-synchronization rate1 – 1.5 hours per day
Eastbound adaptation~ 50 % slower than westbound; 1.5 days per time-zone east
Westbound adaptation~ 1 day per time-zone
DifficultyReadjustment after a time shift is normally more difficult with flights towards the East
Sleep durationGoverned primarily by the point within your circadian rhythm at which you try to sleep
Sensorimotor vs intellectual performanceSensorimotor performance is better in the evening; intellectual performance is better in the morning
Worked Example — Hyderabad → Berlin Layover Hyderabad (IST, UTC+5:30) to Berlin (CET, UTC+1) — a westbound trip of about 4.5 time zones with a 22-hour layover.
• Layover < 24 hours → do NOT shift to local time. Stay on departure (IST) rhythm.
• Relevant time measure for your circadian rhythm: IST (Indian Standard Time).
Reason: short layovers do not give the biological clock time to re-synchronize (only 1–1.5 hours/day shift is possible); attempting to shift will degrade alertness on the return leg.
Exam Tip — Eastbound = Worse Eastbound travel adaptation is 50% slower than westbound. East → 1.5 days per time-zone; West → 1 day per time-zone. "Lose hours, lose sleep."

24. Sleep — NREM & REM

What this section covers The two components of sleep, the four NREM stages, REM sleep timing and function, sleep inertia and the implications of sleep loss for pilots.

Sleep is basically divided into two components:

ComponentPurpose
NREM sleepBody restoration — repair tissues, build bone and muscle, strengthen immune system
REM sleepBrain restoration — strengthening, refreshing and organizing memory

NREM sleep is further divided into four stages from lightest to deepest. Both types of sleep are required to recoup physical and mental energy.

24.1 NREM Sleep Stages

StageDescriptionDuration
NREM Stage 1Transition phase between wakefulness and sleep. Brain activity, eye movement and muscle activity become slower. A person is easily awakened. Waking up in this stage causes a person to feel that he/she has not slept.10 minutes each time
NREM Stage 2Light sleep — the first stage of true sleep. Occupies 50 % of the sleep patterns. Brain activity, eye movement become even slower; cardiac activity decreases.10–25 minutes each time
NREM Stage 3Beginning of deep sleep — slow-wave delta sleep. Brain activity and eye movement approaching zero. If awoken, the person may feel groggy and disoriented for a few minutes.
NREM Stage 4Deep sleep — slow-wave delta sleep. No eye movement or muscle activity. If awoken, the person may feel groggy or disoriented for a few minutes.

24.2 REM Sleep (Paradoxical Sleep)

As we grow older, the time spent in REM sleep declines from 50 % of our sleep for infants, to 20 % of our sleep for adults.

24.3 Sleep Inertia

Definition — Sleep Inertia Refers to the transitional state between sleep and wake, marked by impaired performance, reduced vigilance, and a desire to return to sleep.

24.4 Key Points to Remember

Sleep — Critical Facts
flowchart LR
  W[Wakefulness] --> N1[NREM 1
~10 min
Transition] N1 --> N2[NREM 2
10–25 min
50% of sleep] N2 --> N3[NREM 3
Onset Deep Sleep] N3 --> N4[NREM 4
Deep Sleep
No eye/muscle activity] N4 --> R[REM
70–90 min in
Dreams · Brain wave ≈ awake] R -.cycle repeats with more REM each time.-> N2

25. Mental Health Problems & Disorders

What this section covers The risk of mental health problems among aviation personnel, the Germanwings 9525 case study, and where preventive efforts should focus.

Mental health problems and disorders among pilots, ATCOs, maintenance and other personnel in aviation may impair performance and therefore be a threat to flight safety.

25.1 Case Study — Germanwings Flight 9525

Germanwings 9525 — 24 March 2015

25.2 Why Pilots May Not Report Mental Health

There may be many reasons why a pilot may be reluctant to discuss mental health problems with the examining physician during the annual medical assessment, including fear of losing his or her licence with both personal and financial costs as a result. This may prevent the pilot from receiving adequate and timely help, and this could potentially make the problems worse and prolong the time for recovery.

Best Practice — Reducing Stigma More could probably be done to increase knowledge about mental health problems and reduce stigma so that more pilots and other professionals working in aviation report mental health problems, get treatment, and return to work. This would probably increase individual well-being, but also promote safety.

25.3 Where to Focus Preventive Efforts

Serious mental health disorders (e.g. psychosis) are relatively rare and their onset is difficult to predict. Preventive efforts should be aimed at more common mental health problems such as:

Master Reference Tables & Mnemonics

Purpose Every numerical value and key rule from the chapter consolidated for quick exam-night revision.

M-1. Master Numerical Reference

TopicValueSection
Iconic memory duration0.5 – 1 second5
Visual channel share of information processing70 – 80 %5
Short-term memory duration10 – 20 seconds12
Short-term memory capacity7 ± 2 items12
Long-term memory capacityUnlimited (retrieval may fail)12
Acceptable workload (crew resources)~ 60 %11
Human error rate – simple/repetitive1 in 10011
Human error rate – after practice1 in 1,00011
Startle reflex – motor task recovery5 – 10 seconds10
Age-related response slowing20 – 60 years14
Anthropometric design populationCentral 90 % (disregard 5% lowest & 5% highest)20
Free-running circadian cycle~ 25 hours23
Cued circadian cycle~ 24 hours23
Circadian re-sync rate1 – 1.5 hours/day23
Eastbound adaptation~ 1.5 days/time-zone (50% slower than west)23
Westbound adaptation~ 1 day/time-zone23
Stop-over threshold for adjusting to local time> 24 hours23
Lowest body temperature time04:3023
Highest body temperature time19:0023
Melatonin peak02:00 – 04:0023
Melatonin secretion starts21:0023
Melatonin secretion stops07:3023
NREM Stage 1 duration10 minutes24
NREM Stage 2 duration / share10–25 min / 50 % of sleep24
REM onset after sleep start70 – 90 minutes24
REM cycle duration10 min → up to 1 hour24
REM share – infant vs adult50 % vs 20 %24
Post-nap performance lossUp to 20 minutes24
Life stress scoring – free / normal / high / serious<60 / 60–80 / 80–100 / >10022
Germanwings 9525 — date24 March 201525
Germanwings 9525 — crash distance100 km NW of Nice25
Germanwings 9525 — casualties144 pax + 6 crew25
Cockpit restraint5-point harness with negative-G strap20

M-2. Mnemonics & Memory Aids

ConceptMnemonic
Aviation Psychology aimsD-P-U-I → Describe, Predict, Understand, Influence
Information-processing stagesD-P-D-A-F → Detection, Perception, Decision, Action, Feedback
Workload driversDPST → Difficulty, Parallel, Series, Time
Anderson model phasesC-A-A → Cognitive, Associative, Automatic
STM expansion tools"Chunk & Chain" → Chunking + Association
Long-term memory typesS-E-P → Semantic, Episodic, Procedural
SA-killersSBF-EPI → Stress, Boredom, Fatigue, Emotional, Poor comm., Interruptions
Decision-making seven stepsR-C-A-D-S-E-F → Recognize, Consider, Analyze, Develop, Select, Execute, Follow-up
Communication barriers4-A + 2-I-R → Aggressiveness, Arrogance, Anti-authoritarian, (im)Pulsiveness, Invulnerability, Resignation
Human-centred automation qualities"A-SPA-CFDIE²" → Accountable, Subordinate, Predictable, Adaptable, Comprehensible, Flexible, Dependable, Informative, Error-resistant, Error-tolerant
Control design principlesS-F-S-I-V-S-S-W → Standardization, Frequency, Sequence, Importance, Visual-tactile, Symbolism, Simultaneous, Warnings
Stress observables"P-FlSh-DP-FB" → Perspiration, Flushed Skin, Dilated Pupils, Fast Breathing
Sleep stages1-2-3-4-R → NREM 1 (transition) → 2 (light, 50%) → 3 (onset deep) → 4 (deep) → REM (dreams)
Jet-lag rule"East is Least, West is Best" → East 50% slower; 1.5 d/zone east vs 1 d/zone west
Mental health priority targetsD-A-S → Depression, Anxiety, Substance misuse

M-3. Quick Definitions Recall Sheet

TermOne-Line Definition
Aviation PsychologyApplied psychology focused on human behaviour in aviation systems.
WorkloadMental effort needed to process information.
PerceptionConversion of sensory information into a meaningful structure.
Selective AttentionContinual sampling of inputs to judge relevance.
Divided AttentionTime-sharing of central decision channel between tasks.
VigilanceCapability of remaining alert above a threshold for a period.
ComplacencySelf-satisfaction with one's performance + unawareness of danger.
Motor ProgrammeBehavioural sub-routine learnt by practice and held in LTM.
Reaction TimeDelay between detection, stimulus and muscle contraction.
Startle ReflexReflex-like blink + body jerk to abrupt stimulus.
Human ReliabilityIndividual functioning in the manner he/she is supposed to.
HallucinationFalse perception characterised by distortion of real sensory stimuli.
CognitionMental process of acquiring knowledge by reasoning, intuition or perception.
Risk AssessmentProbability of risk × Impact if it occurs.
Situational AwarenessAccurate appraisal of self, environment and own performance.
AutomationControlling apparatus/process by electronic/mechanical devices replacing the human organism.
AnthropometryStudy of human measurement (static, dynamic, contour-surface).
Eye DatumDefined eye position around which the cockpit is designed.
Trait AnxietyPersonality trait of high neuroticism (persistent worry).
State AnxietyTransient anxiety present in anyone at any time.
ArousalPerson's readiness to respond effectively to a stress factor.
FatigueDeep tiredness from cumulative stressful lifestyle/environment.
ZeitgeberBody's chronological pacemaker — melatonin signals time of day/year.
Sleep InertiaTransitional state between sleep and wake with impaired performance.

M-4. Risk Formula

Risk Assessment Formula Risk = Probability of Occurrence × Impact if it Occurs

Variables:
Probability — likelihood the hazard manifests (low / medium / high).
Impact — severity of consequence (minor / major / catastrophic).

Worked example — Marginal weather decision:
Probability of icing on route = High (forecast supports it).
Impact if encountered without anti-ice = Catastrophic.
→ Risk = High × Catastrophic = Unacceptable. Decision: Don't fly, or re-route below freezing level / with active anti-ice.

M-5. Final Quick-Revision Summary Box

Exam-Night One-Page Recap Memory: Iconic 0.5–1 s · STM 10–20 s, 7±2 · LTM unlimited.
Workload: Acceptable ≈ 60 % · DPST drivers · symptoms = funneling, regression, mental blocking, panic.
Error rate: 1/100 raw → 1/1,000 after practice. Errors are cumulative.
Startle: Motor task back to normal in 5–10 s. Fear potentiates.
Anderson Skill: Cognitive → Associative → Automatic.
Anthropometry: central 90 %, discard top & bottom 5 %.
Restraint: 5-point harness + negative-G strap.
Display rule: Digital for quantitative · Analogue for qualitative. Standardization is the #1 design rule.
Three-pointer altimeter: more misreads than single-pointer.
Stress observables: perspiration, flushed skin, dilated pupils, fast breathing.
Life stress: <60 free · 60–80 normal · 80–100 high · >100 serious. Spouse death = 100.
Circadian: Free-running 25 h · cued 24 h · Lowest body temp 04:30 · Highest 19:00 · Melatonin peak 02–04 · Zeitgeber = Melatonin (pineal gland).
Jet-lag: 1–1.5 h/day re-sync · East 1.5 d/zone (50% slower) · West 1 d/zone · >24 h stopover → shift; <24 h → stay on departure rhythm.
Sleep: NREM 1 = 10 min · NREM 2 = 10–25 min, 50% · REM at 70–90 min · REM 50% infant → 20% adult · Post-nap loss up to 20 min.
Mental health priority: Depression, Anxiety, Substance misuse. Germanwings 9525 (24 Mar 2015, A320, 100 km NW Nice, 144 pax + 6 crew).
Communication barriers: Aggressiveness, Arrogance, Anti-authoritarian, Impulsiveness, Invulnerability, Resignation.
Murphy's Law: if it can be operated wrongly, sooner or later it will be.
Golden Maxim: A superior pilot uses his superior judgment to avoid situations that would require his superior skills.
Capt. Pankaj Pahil