CPL Human Performance common mistakes
CPL Human Performance · Understand the traps and how to avoid them.
When asked which sensory system drives spatial orientation, the candidate answers 'the inner ear' or 'the eyes' alone instead of naming the integrated contribution of vestibular, visual and somatosensory inputs, and then mislabels which cue dominates in a given flight condition.
Revision notes and slide decks often present the senses as separate chapters, so the candidate memorises each in isolation and never builds a model of how the three channels are weighted, and how weighting shifts when visual cues degrade at night or in cloud.
What to do instead
Before the exam, draw a one-page table with columns for vestibular, visual and somatosensory, and rows for 'on the ground', 'in visual flight', 'in cloud or at night', and 'during acceleration'. For each cell note which channel is reliable and which is misleading. Rehearse two or three worked scenarios aloud, such as a prolonged coordinated turn or a night take-off over water, stating which cue is false and why the others cannot correct it.
The candidate confuses the functions of the sympathetic and parasympathetic divisions, or attributes a specific physiological response (pupil dilation, increased heart rate, bronchodilation, digestion) to the wrong branch, especially under the framing of 'fight or flight'.
Both divisions are taught together as a paired list, and under time pressure the candidate recalls the pair but not the direction, because the material was learned as a matching exercise rather than as a functional story about mobilisation versus restoration.
What to do instead
Learn the autonomic nervous system through one concrete event: a sudden engine failure at low altitude. Trace the sympathetic response organ by organ (pupils, heart rate and contractility, airways, blood diversion to skeletal muscle, glucose release, digestion suppressed) and then the parasympathetic counter-regulation afterwards. Practise labelling a blank diagram of the two branches from memory, then check it, until the direction of each effect is automatic.
When a question describes a scenario such as a somatogravic illusion on take-off or a leans illusion after a rate-limited roll, the candidate names the illusion correctly but then states the wrong corrective action, for example 'follow the sensation and level the wings' or 'look outside to re-orient'.
Illusions are memorised as names and definitions, so the candidate can match the label to the scenario but has not learned the operational consequence, which is that the pilot must disregard the false sensation and fly by reference to instruments.
What to do instead
For each illusion you revise, write a three-part card: the manoeuvre that triggers it, the false sensation it produces, and the instrument response that overrides it. Cover the somatogravic effect, the leans, the graveyard spiral, Coriolis illusion and the black hole approach. For each, state explicitly which instrument resolves the ambiguity and why looking outside may not help.
The candidate treats the SHELL model as four unrelated boxes and cannot place a given real-world problem in the correct interface, for example describing a confusing autopilot mode as a 'liveware-hardware' issue when it is a liveware-liveware or liveware-software interface problem, or failing to identify the central liveware as the focus of the model.
Diagrams of SHELL show the components as a static picture, so candidates learn the letters but not the idea that the model is about mismatches at the boundaries between the central human and each surrounding element.
What to do instead
Re-draw SHELL yourself with the human in the centre and the four surrounding blocks, then write one aviation example on each edge: liveware-hardware (control layout), liveware-software (automation logic, checklists, procedures), liveware-environment (weather, ATC, lighting), liveware-liveware (crew interaction, instructor-pilot). Practise classifying five unfamiliar incidents into an interface and justifying the choice in one sentence.
The candidate answers fatigue questions using the number of hours awake alone, ignoring circadian timing, time since last sleep, cumulative sleep debt and sleep inertia, and therefore misjudges when performance risk is actually highest, such as the early-morning window or the period shortly after waking from a nap.
Fatigue is often reduced in study material to a single 'hours on duty' rule, which is easy to remember but does not match the two-process model of sleep regulation that exam questions are built on.
What to do instead
Learn the interaction of the homeostatic sleep drive and the circadian rhythm as a simple graph: rising sleep pressure across the day, with an alerting circadian peak in the late morning and evening and a trough in the early hours. Then apply it to short scenarios, such as a pilot who slept six hours and reports for a 05:00 departure, or one who takes a 40-minute nap before a night approach, and state the dominant risk and the mitigation for each.
The candidate confuses the anatomical and functional divisions of the nervous system, for example placing the cerebellum within the autonomic nervous system, assigning balance to the cochlea, or describing the brainstem as the seat of conscious decision making rather than a relay and vital-function centre.
Neuroanatomy is learned as a list of structures without a map of how they connect, so under exam pressure the candidate retrieves plausible-sounding but mislocated labels.
What to do instead
Build a single hierarchy diagram from memory: central versus peripheral, then somatic versus autonomic, then sympathetic versus parasympathetic, and place each structure from the syllabus on it. For each of the cerebellum, brainstem, hypothalamus and inner ear, write one sentence on its function and one aviation consequence, such as the role of the cerebellum in habituating to unfamiliar motion or the brainstem in processing vestibular input.
The candidate describes CRM as a set of personality traits or as 'good communication', and cannot distinguish the specific behaviours being tested, such as briefings, inquiry and advocacy, workload distribution, monitoring and cross-checking, or the difference between an assertiveness problem and a communication problem.
CRM is discussed in broad, aspirational language in training, so candidates absorb the vocabulary without the behavioural detail that distinguishes one CRM marker from another in a graded scenario question.
What to do instead
Take the standard CRM behaviour categories and, for each, write one observable positive example and one observable failure from a two-crew flight. For inquiry and advocacy, practise the graded escalation phrase: state the observation, state the concern, then state the requirement. When answering, name the behaviour, cite the observable evidence in the scenario, and state the corrective action.
The candidate treats automation as always reducing workload, and answers questions about mode confusion or automation complacency by recommending 'more automation' or 'trust the autopilot', rather than identifying the mismatch between the pilot's mental model of the mode and the aircraft's actual mode.
Automation is taught with an emphasis on capability and reliability, and the failure modes of monitoring, vigilance and mode awareness are covered thinly, so the candidate defaults to a positive view of automation whenever the question is ambiguous.
What to do instead
Study automation as a joint cognitive system: list the known risks, including mode confusion, automation bias, complacency, skill degradation and reduced vigilance during monitoring. For each, write a scenario in which it appears and the countermeasure, such as mode awareness through annunciation cross-checks, active monitoring, and deliberate practice of manual flying. When a question mentions an unexpected aircraft behaviour, first ask whose mental model was wrong.
The candidate answers questions on hearing by reciting the decibel scale without applying it, or confuses the mechanisms of conductive and sensorineural hearing loss, and cannot link noise exposure to the practical cockpit problem of degraded speech intelligibility and misheard clearances.
The physics of sound and the physiology of hearing are revised as separate topics, so the candidate can define each term but cannot reason about an operational consequence such as why high-frequency loss impairs understanding of consonants.
What to do instead
Connect the two: learn that speech intelligibility depends heavily on high-frequency consonant energy, that noise-induced hearing loss typically begins at higher frequencies, and that hearing protection and headset quality therefore matter for safety-critical communication. Practise explaining, in three sentences, why a pilot with early noise-induced loss may still pass a pure-tone test but struggle with radio calls in a noisy environment.
The candidate describes human information processing as a simple input-to-output pipeline and cannot place a failure at the correct stage, so attention, perception, working memory, decision making and response selection are used interchangeably when diagnosing an error in a scenario.
The model is usually presented as a block diagram, and candidates memorise the blocks without learning the characteristic failure at each stage, such as expectation bias in perception, capacity limits in working memory, or plan continuation in decision making.
What to do instead
For each stage of the model, write the signature failure and one aviation example: expectation and perceptual set in perception, chunking and capacity limits in working memory, satisficing and confirmation bias in decision making, and slip versus mistake in response selection. Then take a short incident narrative and label each error with its stage and justify the label in one sentence.