Checklists remind us of the minimum necessary steps and make them explicit. They not only offer the possibility of verification but also instill a kind of discipline of higher performance. They provide a kind of cognitive net. They catch mental flaws inherent in all of us--flaws of memory and attention and thoroughness. And because they do, they raise wide, unexpected possibilities.

He designed a preincision "Cleared for Takeoff " checklist that he put on a whiteboard in each of the operating rooms. He also did something curious: he designed a little metal tent stenciled with the phrase Cleared for Takeoff and arranged for it to be placed in the surgical instrument kits. The metal tent was six inches long, just long enough to cover a scalpel, and the nurses were asked to set it over the scalpel when laying out the instruments before a case. This served as a reminder to run the checklist before making the incision.

"Pause points," as they are called in aviation--points at which the team must stop to run through a set of checks before proceeding.

There are good checklists and bad, Boorman explained. Bad checklists are vague and imprecise. They are too long; they are hard to use; they are impractical. They are made by desk jockeys with no awareness of the situations in which they are to be deployed. They treat the people using the tools as dumb and try to spell out every single step. They turn people's brains off rather than turn them on. Good checklists, on the other hand, are precise. They are efficient, to the point, and easy to use even in the most difficult situations. They do not try to spell out everything--a checklist cannot fly a plane. Instead, they provide reminders of only the most critical and important steps--the ones that even the highly skilled professionals using them could miss. Good checklists are, above all, practical.

When you're making a checklist, Boorman explained, you have a number of key decisions. You must define a clear pause point at which the checklist is supposed to be used (unless the moment is obvious, like when a warning light goes on or an engine fails). You must decide whether you want a DO-CONFIRM checklist or a READ-DO checklist. With a DO-CONFIRM checklist, he said, team members perform their jobs from memory and experience, often separately. But then they stop. They pause to run the checklist and confirm that everything that was supposed to be done was done. With a READ-DO checklist, on the other hand, people carry out the tasks as they check them off--it's more like a recipe. So for any new checklist created from scratch, you have to pick the type that makes the most sense for the situation.

The checklist cannot be lengthy. A rule of thumb some use is to keep it to between five and nine items, which is the limit of working memory. The wording should be simple and exact, Boorman went on, and use the familiar language of the profession. Even the look of the checklist matters. Ideally, it should fit on one page. It should be free of clutter and unnecessary colors. It should use both uppercase and lowercase text for ease of reading. (He went so far as to recommend using a sans serif type like Helvetica.) Boorman was adamant about one further point: no matter how careful we might be, no matter how much thought we might put in, a checklist has to be tested in the real world, which is inevitably more complicated than expected. First drafts always fall apart, he said, and one needs to study how, make changes, and keep testing until the checklist works consistently.

We don't like checklists. They can be painstaking. They're not much fun. But I don't think the issue here is mere laziness. There's something deeper, more visceral going on when people walk away not only from saving lives but from making money. It somehow feels beneath us to use a checklist, an embarrassment. It runs counter to deeply held beliefs about how the truly great among us--those we aspire to be--handle situations of high stakes and complexity. The truly great are daring. They improvise. They do not have protocols and checklists. Maybe our idea of heroism needs updating.

The fear people have about the idea of adherence to protocol is rigidity. They imagine mindless automatons, heads down in a checklist, incapable of looking out their windshield and coping with the real world in front of them. But what you find, when a checklist is well made, is exactly the opposite. The checklist gets the dumb stuff out of the way, the routines your brain shouldn't have to occupy itself with and lets it rise above to focus on the hard stuff.

All learned occupations have a definition of professionalism, a code of conduct. It is where they spell out their ideals and duties. The codes are sometimes stated, sometimes just understood. But they all have at least three common elements. First is an expectation of selflessness: that we who accept responsibility for others--whether we are doctors, lawyers, teachers, public authorities, soldiers, or pilots--will place the needs and concerns of those who depend on us above our own. Second is an expectation of skill: that we will aim for excellence in our knowledge and expertise. Third is an expectation of trust-worthiness: that we will be responsible in our personal behavior toward our charges. Aviators, however, add a fourth expectation, discipline: discipline in following prudent procedure and in functioning with others. This is a concept almost entirely outside the lexicon of most professions, including my own. In medicine, we hold up "autonomy" as a professional lodestar, a principle that stands in direct opposition to discipline. But in a world in which success now requires large enterprises, teams of clinicians, high-risk technologies, and knowledge that outstrips any one person's abilities, individual autonomy hardly seems the ideal we should aim for. It has the ring more of protectionism than of excellence.