The Checklist's Real History: 1840 Ledgers, NASA Fonts and the WHO List

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The popular story says the checklist was born after the 1935 crash of the Boeing B-17 prototype, when a test pilot forgot to release a gust lock. This episode shows the record goes back further: an 1841 New Hampshire House of Representatives journal on the elections of autumn 1840, and an 1853 printed use of the hyphenated word noted by the Oxford English Dictionary. The hosts define a checklist as a quality management tool for complex, repetitive tasks where fatigue and autopilot cause skipped steps. Unlike a to-do list, it does not teach the skill. It ensures sequence and completeness, and it serves as a legal record of due diligence. Aviation built checklists into takeoff, approach, landing and emergencies.

In 2008 the World Health Organization published its surgical safety checklist, and its pilot study reported mortality down 23 percent and complications down 40 percent. A later study of hospitals in Ontario, Canada, found no effect, as teams rushed through it as a mandate. After the crash of Northwest Airlines Flight 255 in Detroit, human factors specialist Earl Wiener testified that there was almost no research on checklist design, which led to NASA studies in 1990 and 1992 by Asaf Degani and Wiener. The episode also covers read-do and do-confirm methods and the problem of safety clutter, defined by researchers in 2018.

• NASA's research found sans serif fonts more legible, with an ideal size of 14 to 20 points and never below 10.
• Lowercase text reads faster than all caps because ascenders and descenders give each word a distinct shape.
• Black on white offers the best contrast, yellow backgrounds also work, and laminated lists need an anti-glare finish.
• A UK frailty checklist for elderly patients struggled because judging frailty needs nuanced clinical judgment.
• A 2017 scuba diving study by Ranapurwala and colleagues found a memorized checklist performed about the same as no checklist.