Normalization of Deviance: How Good Teams Drift Into Disaster
Every shortcut that 'worked last time' becomes the new normal — until it doesn't. Normalization of Deviance: how good teams drift toward their own Challenger moment.
💭 The Challenger didn't fail on launch day. It had been failing, quietly, for years.
No one decides to lower the bar
✈️ The space shuttle broke apart in 1986, but the sociologist Diane Vaughan traced the real cause back years. She called it Normalization of Deviance. NASA had seen the O-ring damage on earlier flights, and each time the shuttle landed safely. Each time, the acceptable margin crept a little wider, until there was none left.
The mechanism never changes:
- a small compromise,
- nothing bad happens,
- the compromise becomes normal.
Then a bigger one. In aviation it's the check you skip because it's always been fine. "It's worked a hundred times" is how standards quietly die. Or the checklist you run from memory instead of reading it.
🫵🏻 Yes Captain, you know who you are — I'm watching you!
Your life drifts the same way
🎯 You run on the same mechanism. You skip breakfast once, then always. You check your phone in bed once, then always. You skip today's triathlon session for the second time in a row (note to myself: finish this post and get on the bike for those 90-minute intervals…)
✅ Each step feels trivial, and from where you stand today nothing looks wrong. That's the trap. So set a pre-deviance standard: while you're calm and rested, write down what "normal" looks like for your sleep, your food, how you're spoken to, your hours.
🚫 Don't trust your in-the-moment judgement. It has already drifted with you. Trust the standard you set when you were clear-headed.
☝🏼 Review it monthly. If today doesn't match it, you've drifted, and now you can correct before the margin runs out. In aviation, that's the difference between a finding and a catastrophe.
