Certify66
← Back to Human Factors
Section 9.4

Factors Affecting Performance

Fitness/health, stress, time pressure and workload, sleep and fatigue, alcohol/medication/drug abuse.

Notes

Factors affecting performance, summary notes

Main ideas
  • Fitness and health (illness, medication side effects) reduce alertness and reaction time, self-certifying "fit for duty" before a shift is a real human factors control, not a formality.
  • Stress, both domestic and work-related, narrows attention ("tunnelling") onto the perceived source of stress, making a technician more likely to miss an unrelated cue.
  • Time pressure and heavy workload push technicians toward shortcuts; awareness of this effect is the first defence against it.
  • Fatigue from poor sleep or shift work degrades judgement as much as alcohol at equivalent levels of impairment, and is worst on night shifts and during a circadian low (roughly 02:00-06:00).
  • Alcohol, over-the-counter medication and drug use all impair judgement and reaction time, most maintenance organisations mandate a minimum "bottle to throttle" style interval before duty.
  • ⚠ Exam trap: fatigue impairs performance like alcohol, and the fatigued person cannot reliably judge their own impairment, which is why duty-time limits exist.
Solved examples
  1. A technician on their fourth consecutive night shift signs off a task without following the full work card sequence. What is the most likely contributing factor?

    Fatigue from circadian disruption on night shift, a fatigued person defaults to habit and skips steps that feel "obviously" complete, even when they are not; fatigue risk management (shift limits, rest periods) exists specifically to control this.

Mind map

Factors affecting performance concept map

Factors Affecting Performance

Quiz

Factors affecting performance quiz

Factors Affecting Performance, quiz

Ref 9.48 of 10Pass 75%
  1. 1. Fatigue from poor sleep or shift work can impair judgement to a degree comparable with:

    Alcohol impairment at equivalent levels
    No measurable effect
    Only a minor effect on reaction time
  2. 2. The circadian low, the period when alertness is naturally lowest, typically falls around:

    02:00-06:00
    12:00-14:00
    18:00-20:00
  3. 3. Stress narrows a technician's attention, an effect often called:

    Tunnelling
    Expansion
    Saturation
  4. 4. A technician skips full documentation on their fourth consecutive night shift. The most likely contributing factor is:

    Fatigue
    Overconfidence from too much rest
    Excess motivation
  5. 5. "Bottle to throttle" style rules exist to control the effect of:

    Alcohol on judgement and reaction time before duty
    Caffeine intake during a shift
    Tool calibration intervals
  6. 6. Both too little and too much to do are risky because:

    Underload causes boredom and overload causes missed steps
    Underload is always safe
    Overload improves accuracy
  7. 7. An adult typically needs how much sleep per 24 hours to avoid a cumulative deficit?

    Around 8 hours
    Around 3 hours
    Around 12 hours
  8. 8. Before self-medicating for a cold before a shift, a technician should consider that:

    Many remedies cause drowsiness and impair performance
    Medication never affects work
    Only prescription drugs matter