CAA NZ AME Human Factors common mistakes
CAA NZ AME Human Factors · Understand the traps and how to avoid them.
Treating the SHELL model as a simple list of four letters and naming each element without describing the interfaces (Liveware–Hardware, Liveware–Software, Liveware–Liveware, Liveware–Environment) or explaining that the central Liveware is the human at the centre of the system.
The model is easy to memorise as an acronym, so candidates stop at definitions and never practise applying the edges, which is what exam questions actually probe.
What to do instead
For every SHELL question, redraw the diagram from memory and write one concrete aviation maintenance example against each interface (e.g. L–H: awkward access to an engine accessory; L–S: confusing tech log layout; L–L: shift handover ambiguity; L–E: hangar noise and heat). Practise until you can name the interface being tested before answering.
Confusing the 'dirty dozen' with the Swiss cheese model or with error classifications, and listing items such as 'stress' and 'complacency' without linking each to a specific maintenance consequence and countermeasure.
The twelve factors are usually learned as a flat list for recall, and candidates do not build the habit of pairing each factor with an outcome and a control.
What to do instead
Build a three-column table: factor, typical maintenance outcome (e.g. fatigue leading to omitted step in a multi-task procedure), and a specific mitigation. Recite it in both directions so you can answer 'which factor is most associated with X' as well as 'what does factor Y cause'.
Mixing up the three error types (skill-based slip and lapse, rule-based mistake, knowledge-based mistake) and treating violations as a fourth type of error rather than a separate category of intentional deviation.
Everyday language uses 'mistake' and 'error' interchangeably, and the distinctions between unintended action, unintended inaction, and deliberate non-compliance are subtle under exam pressure.
What to do instead
Learn a decision tree: was the intention correct? If yes, was the action executed as intended (slip) or omitted (lapse)? If no, was a rule applied wrongly (rule-based) or was there no applicable rule (knowledge-based)? Violations sit outside this tree because the intention itself breaches a known rule. Test yourself with ten short scenarios and classify each.
Answering questions on the error chain and accident causation by jumping straight to the final active error, instead of identifying latent conditions such as inadequate training, poor procedures, or commercial pressure.
Accident reports foreground the person who made the final error, and candidates mirror that narrative rather than reasoning about the organisational layer.
What to do instead
For any scenario, always write the sequence: organisational influence, local conditions, unsafe acts, defences breached. Practise identifying which element is latent and which is active, and note that the fix for latent conditions is usually systemic rather than retraining the individual.
Describing the Reason Swiss cheese model as a single slice or as a chain of events, and failing to explain that defences are independent barriers with dynamic weaknesses that align only occasionally.
The model is often reduced to a picture, and the idea that holes shift with context and that multiple barriers must fail simultaneously is lost.
What to do instead
Write a short paragraph in your own words explaining layered defences, dynamic holes, and the difference between the model and a simple chain of events. Then apply it to a maintenance example such as an incorrect torque being caught by independent inspection.
Confusing the roles and purposes of the safety management system, the quality assurance function, and the human factors training programme, and answering as if all three are the same oversight activity.
These functions overlap in practice and use similar vocabulary, so candidates select whichever option sounds most safety-oriented.
What to do instead
Memorise one-line definitions with distinct verbs: SMS identifies hazards and manages risk across the organisation; quality assurance monitors compliance with procedures and standards; human factors training builds individual and team awareness. Match the verb in the question to the function before choosing an answer.
Treating situational awareness as a single concept and failing to distinguish perception, comprehension, and projection, or failing to recognise the loss of awareness that occurs during highly practised, routine tasks.
Candidates equate situational awareness with 'paying attention', which misses the three-level structure and the specific failure mode of automaticity.
What to do instead
Learn the three levels with a maintenance example each (perception: noticing a warning placard; comprehension: understanding what it means for the task; projection: anticipating the consequence for the next shift). Add a note that routine familiarity and distraction are the main threats, and that verbalising intentions restores awareness.
Explaining fatigue only in terms of total hours awake and ignoring circadian effects, cumulative sleep debt, and the difference between fatigue and stress as performance degraders.
Fatigue is treated as a common-sense topic, so candidates rely on general knowledge rather than the specific mechanisms the syllabus expects.
What to do instead
Learn the key points: performance declines with time awake, worsens during the early-morning circadian low, and accumulates across days of restricted sleep. Distinguish acute from chronic fatigue and note that caffeine and motivation mask rather than reverse impairment. Apply this to roster and night-shift questions.
Answering communication questions by describing 'good communication' in general terms instead of applying specific techniques such as closed-loop communication, readback, standard phraseology, and structured handover.
Communication feels intuitive, so candidates give generic answers and miss the named techniques the examiner is testing.
What to do instead
Memorise and be able to describe four techniques with a maintenance example each: readback of instructions, closed-loop confirmation, standard phraseology to reduce ambiguity, and structured handover covering task status, outstanding work, and known defects. Use the technique names in your answers.
Confusing the purpose of a just culture with a blame-free culture, concluding that no individual is ever accountable, and failing to distinguish honest error from reckless or intentional violation.
The phrase 'no-blame' is widely repeated, and candidates absorb the slogan without the accountability boundary that defines a just culture.
What to do instead
Learn the distinction clearly: honest errors and lapses are reported and learned from without punishment, while reckless conduct and deliberate violations remain subject to normal accountability. Practise scenario questions by asking whether the behaviour was intended and whether the risk was understood, then state the appropriate organisational response.