Chapter 4 - Human Performance and Limitations

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.

4.2 Physiology and Altitude Effects

• 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.

4.3 Vision and Night/Low-Contrast Performance

• 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.

4.4 Spatial Disorientation and Vestibular Illusions

• 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.

4.5 Stress, Fatigue, and Workload

• 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.

4.6 Decision Making and Error Management

• 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).

4.7 Hazardous Attitudes and Antidotes

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

4.8 Medical Fitness, Substances, and Self-Assessment

• 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).

4.9 CRM in Single-Pilot Operations

• 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.

4.10 Key Definitions and Practical Examples

• 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.

Scenario: illusion management

• 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.

4.11 Common Human Factors Exam Traps

• Confusing hyperventilation treatment with hypoxia treatment.
• Memorizing illusion names without knowing practical countermeasures.
• Assuming confidence equals competence under stress.
• Ignoring cumulative fatigue over multiple days.
• Treating ADM as theory only rather than operational behavior.

4.12 Rapid Revision Checklist (Pre-Exam)

• Can identify hypoxia/hyperventilation signs and immediate actions.
• Can explain at least four spatial/visual illusions and mitigations.
• Can apply TEM/ADM logic to a scenario question.
• Can identify hazardous attitudes and antidotes.
• Can justify a conservative no-go/diversion decision on human factors grounds.

References (Primary)

• FAA PHAK (ADM and aeromedical sections): https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/phak