Textbook of Usability

A checklist is a structured list of items to be verified or completed, used to externalise memory requirements and catch lapses. The checklist does not replace expertise — it supplements it by catching the oversights that even experts make under time pressure, fatigue, or distraction.

The aviation checklist was born in 1935 after a fatal B-17 crash caused by a forgotten pre-flight step. Ever since, aviation has relied on checklists for normal operations, emergencies, and configuration changes. The checklist has become one of the fundamental safety tools across aviation.

Atul Gawande's The Checklist Manifesto (2009) documented the extension of checklists to surgery. The WHO Surgical Safety Checklist reduced complications by 36% and deaths by 47% in a multinational trial — by ensuring that critical but easily forgotten steps (patient identity, allergies, surgical site) were performed every time.

Design principles for effective checklists:

• Short enough to be usable — ideally under 10 items per phase
• Comprehensive enough to catch critical items
• Actionable, specific language — "Verify patient allergies" not "Check patient"
• Appropriate stopping points — natural breaks in the workflow
• Physical format that survives real-world conditions (laminated, wall-mounted, digital checklist mode)

In software, checklists appear as setup wizards, pre-submission validation, deployment checklists in CI/CD, and onboarding flows. The same principle applies: externalise what would otherwise have to be remembered.