CPL Human Performance cheat sheet

Hypoxia types: hypoxic (reduced alveolar PO2, e.g. altitude), hypemic (anaemia, CO, blood loss), stagnant (G-force, cold, heart failure), histotoxic (alcohol, cyanide). Only hypoxic hypoxia is corrected by supplemental oxygen.

Time of useful consciousness at 25,000 ft is roughly 3-5 minutes; at 35,000 ft about 30-60 seconds; at 40,000 ft about 15-20 seconds. Time shortens with exertion, cold, and smoking.

Cabins are normally pressurised to a cabin altitude of 5,000-8,000 ft; at 8,000 ft equivalent, arterial saturation is still about 90-93% in a healthy pilot.

Barotrauma: middle-ear squeeze on descent is relieved by Valsalva, Toynbee, or swallowing. Do not fly with an active upper respiratory infection or blocked Eustachian tube.

Decompression sickness risk rises with altitude, repeated exposure, and exercise after diving. Standard guidance is a 24-hour surface interval after non-decompression dives and longer after decompression dives before flying.

Carbon monoxide binds haemoglobin roughly 200-250 times more avidly than oxygen, producing hypemic hypoxia; pulse oximetry may read falsely normal, and headache plus confusion are early signs.

Hyperventilation and hypoxia share dizziness, tingling, and confusion; hyperventilation adds carpopedal spasm. Treat an uncertain case as hypoxia: 100% oxygen and descent.

Otitis barotrauma, sinus barotrauma, and dental pain are pressure-related; equalise early and often, and avoid flying with congested sinuses.

Central nervous system = brain and spinal cord; peripheral nervous system = somatic (voluntary) and autonomic (involuntary) divisions.

Autonomic division splits into sympathetic (fight-or-flight: dilated pupils, raised heart rate, bronchodilation) and parasympathetic (rest-and-digest, vagal slowing).

The vestibular system is part of the inner ear: semicircular canals sense angular acceleration; otolith organs (utricle, saccule) sense linear acceleration and gravity.

Semicircular canals respond to acceleration, not constant velocity; in a prolonged constant-rate turn they return to a neutral signal, so the pilot feels straight and level.

The visual system dominates spatial orientation; when vestibular and visual cues conflict, visual cues are usually more reliable in daylight and in visual meteorological conditions.

Cerebral hypoxia impairs judgement and self-assessment before the pilot notices symptoms, which is why oxygen and descent are the first response rather than waiting for symptoms.

The retina's rods (night, peripheral, motion detection) and cones (colour, acuity, central vision) require about 30 minutes for full dark adaptation; bright light resets it.

The brain has no pain receptors; headache from altitude or hypoxia reflects vascular and sinus effects, not brain tissue pain.

Empty-field myopia: in featureless sky or over water, the resting eye focuses about 1 metre ahead, causing a false horizon and missed distant traffic; scan far and near deliberately.

Night vision: use off-centre viewing (look 5-10 degrees off the target) to place the image on rod-rich peripheral retina; avoid bright white light and use red or dim lighting.

Dark adaptation takes about 30 minutes; exposure to bright light for a few seconds can require several minutes to recover.

Visual illusions: black-hole approach (no ground cues makes the aircraft seem high), runway width illusion, and sloping cloud or terrain causing false horizon.

Somatogravic illusion: acceleration during take-off or go-around is misread as a nose-up attitude, prompting a dangerous pitch-down.

Hearing loss from noise is cumulative and permanent; aircraft noise is worst in the 2,000-4,000 Hz range, and hearing protection plus noise-cancelling headsets reduce exposure.

Airsickness and spatial disorientation both impair performance; visual reference to a true horizon and reducing head movement help.

Colour vision deficiency restricts some licence privileges; red-green deficiency is most common and affects interpretation of aviation lights and charts.

Somatogyral illusion: after a sustained turn, the pilot feels a turn in the opposite direction when the turn stops; trust instruments, not sensation.

Coriolis illusion: a head movement during a sustained turn produces a tumbling sensation, often with nausea; avoid head movement in turns.

Graveyard spiral: in a prolonged constant-rate turn without visual reference, the pilot may not perceive bank or descent; instruments show the true bank and altitude.

The leans: a slow roll below the canal threshold leaves the pilot believing the aircraft is level; a quick glance at the attitude indicator corrects it.

Somatogravic illusion: linear acceleration is interpreted as a pitch-up; during acceleration the correct response is to cross-check the attitude indicator and airspeed.

Black-hole approach: a runway with no surrounding ground lighting makes the approach appear too high, leading to a low approach; use the glidepath indicator and published minima.

Illusions are most likely at night, in visual meteorological conditions over featureless terrain, and after abrupt head movements; disorientation is less likely with continuous instrument reference.

Recovery rule: if disoriented, believe the instruments, keep the aircraft wings level, and avoid abrupt manoeuvres until orientation is regained.

Attention is limited; task saturation causes tunnelling, where the pilot fixates on one instrument and misses other cues.

Sensory memory lasts under a second; short-term (working) memory holds about 7 plus or minus 2 items for 15-30 seconds; long-term memory is effectively unlimited but needs retrieval cues.

Habits and expectations (expectation bias) cause pilots to see what they expect, such as reading a cleared altitude as the assigned one.

Decision models: DECIDE (Detect, Estimate, Choose, Identify, Do, Evaluate) and the OODA loop (Observe, Orient, Decide, Act).

Confirmation bias: seeking evidence that supports an existing plan while ignoring contrary indications; actively seek disconfirming data.

Plan continuation bias (get-there-itis): continuing a plan despite changing conditions; a pre-briefed abort or diversion criterion counters it.

Workload peaks during approach and departure; use checklists and standard calls to offload memory and reduce omission errors.

Situational awareness has three levels: perception of elements, comprehension of meaning, and projection of future state; loss of Level 3 is the most dangerous.

SHELL model: Software (procedures, checklists), Hardware (aircraft, controls), Environment (weather, ATC, terrain), and Liveware (people). Mismatch at the Liveware interfaces produces error.

The central Liveware block is the pilot; the most error-prone interfaces are Liveware-Liveware (crew interaction) and Liveware-Software (procedure design).

Threat and Error Management (TEM) has three components: threat avoidance, error trapping, and undesired aircraft state (UAS) management.

A threat is an external event (weather, terrain, ATC, mechanical) that increases operational complexity; an error is a crew action or inaction that deviates from intention or expectation.

Error types: slips (correct intention, wrong execution), lapses (memory failure), mistakes (wrong intention), and violations (deliberate deviation from rules).

CRM skills: communication, leadership and team building, situational awareness, decision making, workload management, and fatigue management.

Assertiveness and graded levels of escalation (question, suggest, state concern, take control) are standard CRM tools for challenging a captain.

Just culture distinguishes human error (console and correct), at-risk behaviour (coach), and reckless behaviour (sanction); reporting is protected to encourage disclosure.

Stress is a non-specific response to demand; acute stress raises heart rate and alertness, while chronic stress degrades performance and health.

Yerkes-Dodson curve: performance peaks at moderate arousal; too little causes complacency, too much causes narrowing of attention and errors.

Fatigue types: acute (single long duty), chronic (cumulative over days), and circadian (body-clock low points around 0300-0500 and 1500-1700).

Sleep need is typically 7-9 hours per night; sleep debt accumulates and cannot be fully repaid by one long sleep.

Sleep inertia: grogginess for 15-30 minutes after waking, especially after deep sleep; avoid critical decisions immediately on waking.

Napping 20-30 minutes restores alertness without deep-sleep grogginess; longer naps risk inertia.

Caffeine has a half-life of about 5-6 hours; caffeine late in the day worsens sleep quality and masks rather than cures fatigue.

Controlled rest on the flight deck (short, planned, one pilot at a time) is a recognised fatigue countermeasure where permitted by the operator.

Automation levels run from fully manual to fully automatic; higher automation reduces workload in normal operations but can increase it when the automation fails or is misunderstood.

Automation complacency: monitoring vigilance drops as trust in automation rises, so failures are detected later.

Automation bias: the crew favours the automation's output over their own assessment; cross-check with raw data and independent sources.

Mode confusion: the crew believes the aircraft is in a different mode than it is; always verify the armed and active modes after any change.

Skill degradation: manual flying skills decay with heavy automation use; practise hand flying and raw-data approaches regularly.

Standard calls, sterile flight deck below 10,000 ft, and a clear briefing of automation use reduce mode and communication errors.

The pilot monitoring must actively monitor, not just watch; a callout of a deviation is expected and should not be treated as criticism.

Effective CRM briefs cover threats, roles, automation level, and the plan for a go-around or diversion before departure.