CAA NZ PPL Human Factors common mistakes
CAA NZ PPL Human Factors · Understand the traps and how to avoid them.
Answering questions about hypoxia by recalling the altitude figures for supplemental oxygen rules instead of identifying the insidious onset and the effect of time of useful consciousness; candidates pick the number that 'sounds right' rather than reasoning about impairment.
The oxygen regulations and the physiological effects of hypoxia are learned separately, so under exam pressure candidates retrieve the regulatory threshold (e.g. 10,000 ft) when the question is actually asking about symptoms or time of useful consciousness at a given altitude.
What to do instead
Before answering, classify the question: is it regulatory (what altitude triggers what requirement) or physiological (what happens to the pilot)? For physiological questions, recall that hypoxia is insidious, that euphoria and impaired judgement precede obvious symptoms, and that time of useful consciousness falls sharply with altitude. Practise writing out a small table of altitude versus time of useful consciousness and symptoms from your own study notes, then explain each row aloud without looking.
Treating spatial disorientation as something that only happens to other pilots in cloud, and choosing 'trust your instruments' as a reflex answer without distinguishing the types of illusion (somatogravic, somatogyral, leans, black hole approach) or the correct recovery technique.
The phrase 'trust your instruments' is memorised as a slogan, so candidates stop there and cannot match a described scenario to the specific illusion or the specific recovery action, which is what the question actually tests.
What to do instead
Learn each illusion by its trigger and its false sensation: somatogravic from linear acceleration during take-off or go-around (false nose-up), somatogyral from prolonged rotation (false turn), the leans from a slow roll below the detection threshold, and black hole approach from a lack of visual cues at night. For each, state the correct response: recognise the conflict, cross-check with instruments, and if disoriented without visual reference, maintain control by reference to instruments and consider a controlled climb. Write a one-line cue for each illusion and test yourself by reading only the scenario.
Confusing the effects of alcohol, fatigue, and medication, and applying a single 'eight hours bottle to throttle' rule to every substance, including over-the-counter antihistamines and prescription drugs.
The bottle-to-throttle figure is widely repeated in training lore, while the actual regulatory and physiological points about impairment, hangover effects, and the unpredictable interaction of drugs with altitude are less rehearsed.
What to do instead
Separate the three topics in your notes. For alcohol, know both the regulatory limit and the fact that impairment and hangover effects persist after blood alcohol falls. For fatigue, learn the difference between acute sleep loss and cumulative fatigue, and the role of circadian low points. For medication, know that any drug affecting the central nervous system is a concern, that individual response varies, and that altitude can amplify effects. Answer by first deciding which category the scenario describes, then applying that category's rules.
Mixing up the causes and signs of hyperventilation and hypoxia, and choosing 'give oxygen' for a hyperventilating pilot or 'slow the breathing rate' for a hypoxic one.
Both present with dizziness, tingling, and a sense of unreality, and both are taught in the same lesson, so the distinguishing features (onset context, colour, response to oxygen, breathing pattern) blur together.
What to do instead
Build a two-column comparison. Hyperventilation typically follows stress or anxiety, produces tingling in the extremities and around the mouth, and improves when breathing rate is controlled. Hypoxia follows altitude exposure or a supply failure, may show cyanosis, and improves with oxygen and descent. Learn the practical rule: when in doubt at altitude, treat as hypoxia first (oxygen and descent), because hypoxia is the more immediately dangerous condition. Then answer by matching the scenario's context and signs to the correct column.
Answering decompression and cabin pressure questions by describing what the pilot should do without accounting for the sequence: donning oxygen first, then establishing communication and initiating an emergency descent, and the risk of decompression sickness afterwards.
Candidates memorise the individual items but not their priority order, and exam questions often test ordering or the reason for the order rather than the items themselves.
What to do instead
Learn the decompression response as a reasoned sequence: recognise the event (noise, fogging, ear discomfort, rush of air), don oxygen immediately because useful consciousness is limited, then descend to a breathable altitude, then communicate. Understand why oxygen comes first: at high cabin altitudes the time available is short and communication can wait. Also learn that dissolved nitrogen can cause decompression sickness after the event, so seek medical advice and avoid further exposure. Rehearse the sequence as a numbered list and justify each step's position.
Treating human error models as vocabulary to memorise rather than as tools, so candidates can define 'error' and 'violation' but cannot classify a described behaviour or select the appropriate countermeasure.
The models are taught as definitions, and exam questions that present a scenario require applying the model, which is a different skill from reciting it.
What to do instead
Practise classifying short scenarios: was the action unintended (a slip or lapse) or intended but non-compliant (a violation)? Was the error in perception, decision, or action? For each classification, link a countermeasure: checklists and standard operating procedures for slips, briefing and cross-checking for decision errors, and a just culture with clear reporting for violations. Work through at least a dozen invented scenarios and justify each classification in one sentence.
Confusing the components of the SHELL model or the Swiss cheese model, such as placing 'liveware' in the wrong position or treating the holes in the cheese as causes rather than as the alignment of latent conditions and active failures.
The diagrams are simple, so candidates skim them and then answer from a vague memory of the picture rather than from the logic of the model.
What to do instead
Redraw each model from memory and explain it in your own words. For SHELL, state that liveware is at the centre and that the interfaces (liveware-hardware, liveware-software, liveware-environment, liveware-liveware) are where mismatches occur. For the Swiss cheese model, explain that each slice is a defence, the holes are weaknesses, and an accident occurs when holes line up; distinguish active failures from latent conditions. Then answer questions by locating the scenario at a specific interface or slice.
Giving generic answers about situational awareness and workload, such as 'maintain situational awareness', instead of identifying the level of situational awareness lost (perception, comprehension, or projection) or the specific workload management technique.
These topics invite vague language, and candidates default to the phrase they have heard most often rather than the specific concept the question is testing.
What to do instead
Learn situational awareness as three levels: perception of cues, comprehension of their meaning, and projection of future states. When a scenario describes a pilot who saw the cues but misread them, the failure is at comprehension, not perception. For workload, learn specific techniques: prioritisation, delegation, shedding low-priority tasks, and using automation appropriately. Answer by naming the level or technique explicitly rather than offering a general statement.
Applying the wrong communication or crew resource management principle to a single-pilot scenario, such as describing a challenge-and-response cross-check between two crew members when the question concerns a pilot flying alone.
Crew resource management is taught mostly in multi-crew contexts, so candidates transfer multi-crew answers to single-pilot questions without noticing the mismatch.
What to do instead
Read the scenario carefully for the number of crew before answering. For single-pilot operations, think in terms of self-briefing, verbal callouts, written checklists, passenger briefing, and using air traffic services as a resource. For multi-crew, think in terms of assertiveness, briefing, monitoring, and closed-loop communication. Prepare a short list of single-pilot resources and practise converting a multi-crew answer into its single-pilot equivalent.
Ignoring the effects of ageing, fitness, and dehydration, and answering as though the pilot population is uniform; candidates miss questions about the reduced tolerance of older pilots to altitude, fatigue, and acceleration.
These factors receive less lesson time than the headline topics, so candidates rely on intuition, which tends to underestimate how much these variables change tolerance.
What to do instead
Learn the key points: cardiovascular and respiratory capacity declines with age, hydration status affects tolerance to heat, altitude, and g-forces, and fitness influences recovery from fatigue. Understand that individual variation is large but the direction of effect is consistent. When a question describes a pilot with several risk factors, answer by considering their combined effect rather than dismissing any single factor as minor.