In 1993, Gordon Dupont developed a core human factors framework for Transport Canada known as the “Dirty Dozen”. These twelve elements are not a comprehensive list of every human error precursor—ICAO, for example, lists over 300—but they represent the most common and high-impact conditions that degrade human performance and provoke safety failures in aviation. Approximately 80% of all maintenance and planning errors involve a breakdown in one of these twelve areas.

Before you complete Lesson 1, let’s test your ability to diagnose these twelve precursors. Read the operational clues below, analyze the human factors at play on the hangar floor or in the CAMO planning office, and complete the crossword puzzle.