Chapter 4 - Human Performance and Limitations

Chapter 4

These notes are exam-focused for CASA PPL human factors. They connect physiology, psychology, and practical in-flight decision making.

4.1 Human Factors Big Picture

Most accidents have a human factors contribution even when a technical issue exists.
Human limitations are predictable; good pilots use systems (checklists, briefings, SOPs, margins) to manage them.
Performance is dynamic: stress, fatigue, workload, and health status can change rapidly across a flight.

Hypoxia: inadequate oxygen at tissue level.
- Types include hypoxic and hypemic (conceptual awareness).
- Early signs: poor judgment, euphoria, visual degradation, slowed responses.
Hyperventilation:
- Caused by anxiety/workload more than low oxygen at typical low altitudes.
- Symptoms can mimic hypoxia; correct with controlled breathing.
Trapped gas:
- Ears/sinuses/GI discomfort from pressure change.
- Do not fly with blocked sinuses or unresolved ear equalization problems.
Decompression sickness and high-altitude concerns are less common in basic PPL ops but examinable conceptually.

Central vision best for detail/color in daylight.
Night vision relies more on peripheral retina; use off-center scanning.
Night adaptation takes time; bright light exposure degrades adaptation.
Common visual limitations:
- Empty field myopia
- Autokinesis
- False horizon
- Black-hole approach illusion
Practical actions:
- Structured scan
- Instrument cross-check
- Stable approach criteria.

Vestibular system is unreliable in prolonged turns/accelerations.
Common illusions:
- The leans
- Coriolis illusion
- Somatogravic illusion
- Graveyard spiral tendency
Countermeasures:
- Trust validated instrument indications
- Maintain scan discipline
- Avoid abrupt head movements in IMC/night.

Acute stress may narrow attention; chronic stress degrades baseline performance.
Fatigue reduces reaction speed, memory, and error detection.
Workload overload leads to task shedding and tunnel vision.
Management tools:
- Preflight preparation quality
- Prioritization (aviate, navigate, communicate)
- Automation management
- Early diversion decisions.

Aeronautical decision-making models (e.g., DECIDE/3P style concepts) are structured ways to avoid impulsive errors.
Threat and Error Management (TEM):
- Identify threats (weather, terrain, traffic, fatigue)
- Trap/manage errors early
- Maintain safety margins.
Situational awareness elements:
- Perception
- Comprehension
- Projection (what happens next).

Typical hazardous attitudes:
- Anti-authority
- Impulsivity
- Invulnerability
- Macho
- Resignation
Exam expectation: recognize attitude from behavior and apply correct antidote mindset.

Never fly when medically unfit.
Alcohol, sedatives, many antihistamines, and some pain medications impair pilot performance.
Dehydration and heat stress reduce cognitive and physical performance.
Use a formal personal fitness check (sleep, stress, illness, medication, hydration, emotional state).

Single-pilot CRM still applies:
- Use passengers as resources (lookout, checklists, spotting traffic/weather)
- Effective radio communication
- Assertive but controlled decision making
- Time management and phase-of-flight briefing discipline.

Hypoxia: insufficient oxygen delivery to tissues.
- Example: pilot becomes unusually confident and misses checklist items at altitude.
Hyperventilation: excessive breathing that lowers CO2, causing dizziness/tingling/anxiety.
- Example: high workload after weather deviation leads to rapid breathing and degraded concentration.
Situational awareness: understanding what is happening now and what is likely next.
- Example: noticing lowering cloud base early and deciding to divert before escape options narrow.
TEM (Threat and Error Management): identify threats, trap errors, and maintain margins.
- Example: known crosswind + fatigue threat prompts stricter stabilized approach gate and earlier go-around trigger.
Hazardous attitude: mindset pattern that increases risk.
- Example: “I can handle this no matter what” aligns with macho/invulnerability patterns.

Night approach over dark terrain with few visual cues feels too high.
Correct response: trust instrument profile and stabilized criteria rather than seat-of-pants sensation.

flowchart LR
    A[Identify Threats] --> B[Assess Risk]
    B --> C[Decide Controls]
    C --> D[Execute]
    D --> E[Monitor Outcome]
    E --> A

Domain	Early cue	Likely effect if unmanaged	Practical countermeasure
Fatigue	Slower thinking, fixation	Procedural errors	Slow down, checklist discipline, reduce workload
Stress	Tunnel vision	Poor prioritization	Aviate-navigate-communicate reset
Hypoxia risk	Poor judgment, euphoria	Decision quality collapse	Descend, oxygen as fitted, reassess
Hyperventilation	Tingling, dizziness	Loss of control precision	Controlled breathing and task simplification

Illusion	Typical trigger	Primary correction
Autokinesis	Isolated light at night	Move scan, confirm with instruments
False horizon	Sloping cloud/terrain lights	Trust attitude instrument
Black-hole approach	Dark approach environment	Stabilized profile and instrument cross-check
The leans	Slow unnoticed bank changes	Instrument scan discipline

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Chapter 4

prepared by Raptor K