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Meaning of Software in the SHEL model

Aviation Mechanic General (AMG) practice question 14 of 16 on Human Factors. ACS element AM.I.L.K2 · difficulty: recall. Want to answer it in a timed quiz? Use the Aviation Mechanic General (AMG) practice mode.

Question bank updated 2026-09-22

QUESTIONIn the SHEL model used to investigate and evaluate maintenance errors, what does the software component include?

  1. ATemperature, humidity, sound, light, and the time of day
  2. BThe technician's interaction with managers, peers, and family
  3. CManual and checklist layout, symbology, and language
Show the answer and explanation

Correct answer: C. Manual and checklist layout, symbology, and language

  • A — incorrect These belong to the environment component of SHEL, not to software.
  • B — incorrect Interaction with other people, both on and off the job, is the liveware component of SHEL.
  • C — correct The handbook explains that software in SHEL is not limited to computer programs; it takes a broader view that includes manual layout, checklist layout, symbology, language (technical and nontechnical) and computer programs.

BACKGROUND

The SHEL model is a concept for investigating and evaluating maintenance errors, initiated by Professor Elwyn Edwards in 1972 and modified by Captain Frank Hawkins in 1975. The acronym stands for Software, Hardware, Environment and Liveware, and the model examines the technician's interaction with each of these four components. The term software is not used in the everyday computer sense; it includes manual layout, checklist layout, symbology, language and computer programs. Hardware covers the location and accessibility of components and tooling, environment covers temperature, humidity, sound, light and time of day, and liveware covers interaction with managers, peers, family, friends and self.

STUDY TIP

Learn what each SHEL letter contains, and especially that software means procedures and documentation rather than just computer code.

KEY POINTS

  • SHEL stands for Software, Hardware, Environment and Liveware.
  • Software includes manual and checklist layout, symbology, language and computer programs.
  • The model looks at how the technician interacts with each component.

SOURCES

  • FAA-H-8083-30B ch14 "Resources" (SHEL model discussion)
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SkyDrill is not affiliated with the FAA. This is an original practice item based on FAA-H-8083-30B Aviation Maintenance Technician Handbook – General, 14 CFR part 43 and part 65. Regulations and handbooks are revised; confirm details against the current edition.