Human Factors: Basic Concepts
What the exam tests
Human Factors: Basic Concepts tests whether you can define the person-centred approach to aviation safety and apply the SHEL/SHELL model to real interfaces, rather than recite psychology. Expect questions on the liveware-centred model, mismatches at interfaces, safety culture and the difference between human factors and ergonomics.
Core rules
- SHEL model: Software (procedures, checklists, manuals, automation logic), Hardware (aircraft, displays), Environment (cabin, ATC, weather, organisation), Liveware (people). In SHELL the second L is other people; the central L is the individual.
- Mismatch at any interface creates error potential; the aim is to design tolerances, not to demand perfect humans.
- Human factors concerns people in their working and living context: their relationship with machines, procedures, environment and each other.
- Safety is improved through design, training, procedures and organisational defences, not blame.
- Reason's model: accidents result from latent conditions and active failures aligning through defences (Swiss cheese).
Worked example
An operator introduces a new EFB performance app. Pilots must enter runway condition, weight and temperature; the app outputs V speeds. A pilot enters Fahrenheit while the app expects Celsius. This is a Software-Liveware mismatch, worsened by a Software-Hardware mismatch (no unit lock or warning). The fix is a design barrier (unit selection, plausibility check), not retraining alone.
Traps that cost marks
- Calling SHEL 'Shell' and forgetting the second L (other liveware).
- Treating human factors as only attitudes or CRM.
- Assuming the person is the problem; exam answers favour systemic defences.
- Confusing active failures with latent conditions.