Human Factors
Private Pilot ACS · Area I · Task H · 14 CFR 61, 14 CFR 91, FAA-H-8083-25
Everything you need to know about Human Factors for your private pilot checkride. Aligned to FAA-S-ACS-6C Task I-H, covering i'm safe preflight checklist, adm decision-making models, aeromedical factors.
I'M SAFE Preflight Checklist AIM 8-1-1 §
I'M SAFE — Full Assessment §
I — Illness: Any symptoms that could impair? A cold traps gas in sinuses and middle ear (barotitis) during altitude changes. A fever impairs judgment and concentration. Ground yourself if sick.
M — Medication: ANY medication requires assessment. Even OTC antihistamines and decongestants cause drowsiness. Consult an AME for any regular medication. Never start a new medication the day of a flight.
S — Stress: Financial, relationship, work, family stress all reduce cognitive reserve and increase task saturation. High stress = less mental bandwidth for flying.
A — Alcohol: 8-hour rule is the legal minimum. FAA recommends 24 hours. Even after 8 hours, hangover effects (dehydration, metabolic byproducts) still impair performance.
F — Fatigue: 17 consecutive hours awake = performance impairment equivalent to 0.05% BAC. 24 hours = 0.10% BAC equivalent. No stimulant (caffeine, etc.) corrects true fatigue.
E — Emotion: Grief, anger, excitement, euphoria — each impairs judgment differently. Anger narrows focus. Euphoria promotes risk-taking. Grief reduces situational awareness.
M — Medication: ANY medication requires assessment. Even OTC antihistamines and decongestants cause drowsiness. Consult an AME for any regular medication. Never start a new medication the day of a flight.
S — Stress: Financial, relationship, work, family stress all reduce cognitive reserve and increase task saturation. High stress = less mental bandwidth for flying.
A — Alcohol: 8-hour rule is the legal minimum. FAA recommends 24 hours. Even after 8 hours, hangover effects (dehydration, metabolic byproducts) still impair performance.
F — Fatigue: 17 consecutive hours awake = performance impairment equivalent to 0.05% BAC. 24 hours = 0.10% BAC equivalent. No stimulant (caffeine, etc.) corrects true fatigue.
E — Emotion: Grief, anger, excitement, euphoria — each impairs judgment differently. Anger narrows focus. Euphoria promotes risk-taking. Grief reduces situational awareness.
PHAK Ch.17; AIM 8-1-1
Hazardous Attitudes — All Five §
| Attitude | Thought Pattern | Antidote |
|---|---|---|
| Anti-authority | "Rules are for others, not me" | "Follow the rules — they're usually right" |
| Impulsivity | "Do something, NOW!" | "Not so fast — think first" |
| Invulnerability | "Accidents happen to others, not me" | "It could happen to me" |
| Macho | "I can do this — watch me" | "Taking chances is foolish" |
| Resignation | "What's the use? I can't do anything" | "I'm not helpless. I can make a difference" |
A pilot may exhibit multiple attitudes. Recognizing and actively applying the antidote in the moment is a core ACS skill and a common DPE oral question.
PHAK Ch.17; AC 60-22
ADM Decision-Making Models PHAK Ch.17 §
DECIDE Model §
A six-step process for in-flight decision making:
Detect — recognize a change or problem
Estimate — assess the need to react
Choose — select the best course of action
Identify — determine the specific steps to take
Do — execute the action
Evaluate — assess the outcome and cycle back
DECIDE is a continuous loop, not a one-time process. As new information emerges, restart the cycle.
Detect — recognize a change or problem
Estimate — assess the need to react
Choose — select the best course of action
Identify — determine the specific steps to take
Do — execute the action
Evaluate — assess the outcome and cycle back
DECIDE is a continuous loop, not a one-time process. As new information emerges, restart the cycle.
PAVE Risk Assessment §
Preflight risk identification across four categories:
P — Pilot: Is the pilot current? Proficient? Healthy? Stressed? Fatigued? Using I'M SAFE?
A — Aircraft: Is it airworthy? Appropriate for this flight? Properly equipped?
V — enVironment: Weather, terrain, airspace, destination airport, time of day. What are the hazards?
E — External pressures: Time pressure, schedule, passenger expectations, cost. Are these distorting the go/no-go decision?
3P Model: Perceive the hazards, Process the risk, Perform risk management action — then evaluate and repeat.
P — Pilot: Is the pilot current? Proficient? Healthy? Stressed? Fatigued? Using I'M SAFE?
A — Aircraft: Is it airworthy? Appropriate for this flight? Properly equipped?
V — enVironment: Weather, terrain, airspace, destination airport, time of day. What are the hazards?
E — External pressures: Time pressure, schedule, passenger expectations, cost. Are these distorting the go/no-go decision?
3P Model: Perceive the hazards, Process the risk, Perform risk management action — then evaluate and repeat.
PHAK Ch.17
SRM — Single-Pilot Resource Management §
In a single-pilot aircraft, all CRM responsibilities fall on one person:
• Task management: Prioritize and sequence tasks. Aviate → Navigate → Communicate.
• Automation management: Know what the GPS/autopilot is doing at all times. Verify automation inputs match your intentions.
• Risk assessment: Continuously apply PAVE and DECIDE.
• Situational awareness: Know where you are, where you're going, what's ahead, what the aircraft is doing, and what options you have.
• Use of all resources: ATC, FSS, other pilots on CTAF, passengers who notice things, written checklists.
• Task management: Prioritize and sequence tasks. Aviate → Navigate → Communicate.
• Automation management: Know what the GPS/autopilot is doing at all times. Verify automation inputs match your intentions.
• Risk assessment: Continuously apply PAVE and DECIDE.
• Situational awareness: Know where you are, where you're going, what's ahead, what the aircraft is doing, and what options you have.
• Use of all resources: ATC, FSS, other pilots on CTAF, passengers who notice things, written checklists.
PHAK Ch.17; AC 60-22
Aeromedical Factors AIM 8-1 §
Hypoxia Types §
| Type | Cause | Example |
|---|---|---|
| Hypoxic | Low O₂ partial pressure at altitude | High altitude flight |
| Hypemic | Blood cannot carry O₂ (CO poisoning, anemia) | Cabin heat leak, CO poisoning |
| Stagnant | Blood circulation slowed | High G-forces, heart failure |
| Histotoxic | Cells cannot use O₂ despite adequate delivery | Alcohol, narcotics, cyanide |
Night vision degradation: Begins at 5,000 ft MSL — use supplemental O₂ at night above this altitude even though legally not required.
O₂ legal requirements: 12,500–14,000 ft >30 min → pilot must use O₂. Above 14,000 → continuous O₂ for crew. Above 15,000 → O₂ provided for all occupants.
AIM 8-1-2; 14 CFR 91.211
Spatial Disorientation Types §
| Illusion | What Happens | Danger |
|---|---|---|
| The Leans | Gradual bank undetected; leveling feels banked | Re-banks to feel "level" |
| Graveyard spiral | Constant bank feels level; back pressure tightens spiral | Structural failure |
| Coriolis | Head movement in sustained turn feels like tumbling | Severe disorientation |
| Somatogravic | Acceleration feels like nose-high pitch | Pushes forward at low altitude |
| Graveyard spin | Stopped spin feels like opposite spin | Re-enters spin |
| Black hole approach | No visual cues → misjudges glidepath | CFIT on approach |
AIM 8-1-5
Vision: Rods vs Cones & Night §
Cones: Located at the fovea (center of retina). Detect color and fine detail. Require relatively bright light. Daytime vision. Looking directly at an object uses cones.
Rods: Located peripherally. Detect motion and low light. No color. Daytime vision impaired; used for night vision. Looking 5–10° off-center (eccentric viewing) uses rods — use this at night to detect dim objects.
Dark adaptation: 30 minutes for full adaptation. Destroyed immediately by bright white light. Red cockpit lighting preserves dark adaptation.
Foveal scotoma: Looking directly at a very dim object makes it disappear — you're using cones, which need more light. Look to the side to see it with rods.
Rods: Located peripherally. Detect motion and low light. No color. Daytime vision impaired; used for night vision. Looking 5–10° off-center (eccentric viewing) uses rods — use this at night to detect dim objects.
Dark adaptation: 30 minutes for full adaptation. Destroyed immediately by bright white light. Red cockpit lighting preserves dark adaptation.
Foveal scotoma: Looking directly at a very dim object makes it disappear — you're using cones, which need more light. Look to the side to see it with rods.
AIM 8-1-5
Alcohol, Fatigue & Medication Rules §
Alcohol rules:
• 8-hour bottle-to-throttle minimum (14 CFR 91.17)
• BAC must be below 0.04% (less than half of legal driving limit in most states)
• FAA recommends 24 hours for full metabolic clearance
• Hangover effects: dehydration, poor judgment, impaired reaction time — even with BAC at zero
Fatigue TUC (Time of Useful Consciousness) at altitude:
• FL250: ~3–5 minutes
• FL300: ~1–2 minutes
• FL350: ~30–60 seconds
Medication principle: If the condition requires medication, the condition itself may be disqualifying — regardless of the medication. Always consult an AME.
• 8-hour bottle-to-throttle minimum (14 CFR 91.17)
• BAC must be below 0.04% (less than half of legal driving limit in most states)
• FAA recommends 24 hours for full metabolic clearance
• Hangover effects: dehydration, poor judgment, impaired reaction time — even with BAC at zero
Fatigue TUC (Time of Useful Consciousness) at altitude:
• FL250: ~3–5 minutes
• FL300: ~1–2 minutes
• FL350: ~30–60 seconds
Medication principle: If the condition requires medication, the condition itself may be disqualifying — regardless of the medication. Always consult an AME.
14 CFR 91.17; AIM 8-1-1