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Share of accidents that are maintenance-related human error

Aviation Mechanic General (AMG) practice question 12 of 16 on Human Factors. ACS element AM.I.L.K1 · difficulty: applied. Want to answer it in a timed quiz? Use the Aviation Mechanic General (AMG) practice mode.

Question bank updated 2026-09-22

QUESTIONAccident data cited in FAA-H-8083-30B attribute approximately 75 to 80 percent of all aviation accidents to human error, and about 12 percent of those human-error accidents are maintenance related. Out of 1,000 aviation accidents, about how many would be maintenance-related human-error accidents?

  1. AAbout 120
  2. BAbout 750 to 800
  3. CAbout 90 to 100
Show the answer and explanation

Correct answer: C. About 90 to 100

  • A — incorrect This applies the 12 percent figure to all 1,000 accidents instead of only to the 75 to 80 percent that are attributed to human error.
  • B — incorrect This is the number of accidents attributed to human error in total; the maintenance-related portion is only about 12 percent of that figure.
  • C — correct Human error accounts for 750 to 800 of the 1,000 accidents, and 12 percent of that range is 90 to 96, so roughly 90 to 100 accidents are maintenance-related human-error events.

BACKGROUND

The Aviation Maintenance Technician Handbook - General (FAA-H-8083-30B) opens its human factors chapter with a review of accident-related data. That review indicates that approximately 75 to 80 percent of all aviation accidents are the result of human error, and that of those accidents, about 12 percent are maintenance related. The handbook adds that pilot errors tend to have immediate and visible effects, while maintenance errors tend to be more latent and less obvious, though they can be just as lethal. Working the percentages in sequence is the key to this kind of question.

STUDY TIP

When a question stacks two percentages, apply them one after the other rather than to the original total. Know both figures: 75 to 80 percent human error, about 12 percent of those maintenance related.

KEY POINTS

  • About 75 to 80 percent of aviation accidents result from human error.
  • About 12 percent of those human-error accidents are maintenance related.
  • Apply the 12 percent to the human-error subset, not to all accidents.

SOURCES

  • FAA-H-8083-30B ch14 "Importance of Human Factors"
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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.