FAA Aviation Mechanic General (AMG)Regulations, Records and Human FactorsHard
A technician is studying the SHEL model of human factors to understand why an installation error occurred. The technician determines that the error resulted from following a poorly written, ambiguous checklist step in the maintenance manual. Which component of the SHEL model does this represent?
- ALiveware
- BHardware
- CEnvironment
- DSoftware
Show answer & explanationAnswer & explanation
Correct answer: D. Software
In the SHEL model, 'Software' represents non-physical aspects of the system such as procedures, checklists, manuals, and computer programs. An ambiguous checklist step is a Software-related human factors issue, distinct from Hardware (physical equipment), Environment (physical/organizational surroundings), or Liveware (people).
Why the other options are wrong
- A. Liveware refers to people (the technician and others), not written material.
- B. Hardware refers to physical tools, equipment, and aircraft structure, not written procedures.
- C. Environment refers to physical and organizational conditions surrounding the task, not documentation.
SHEL Model
A human factors model describing interactions between Software (procedures/manuals), Hardware (equipment/tools), Environment (physical/organizational surroundings), and Liveware (people), centered on the individual (Liveware) at the core.
- Software = procedures, manuals, checklists, computer programs
- Hardware = tools, equipment, physical aircraft components
- Environment = physical, organizational, and social surroundings
- Liveware = the central human element interacting with all others
Memory trick: SHEL: Software, Hardware, Environment, Liveware—people at the center, everything else fits around them like puzzle pieces.