No Acceptable Failure Modes

More about No Acceptable Failure Modes

They asked me, one last time, if I was satisfied. It’s the wrong word, but it’s the one
they use when the checklists run out. Satisfaction suggests pride, or relief. What I
have is closure. Every compromise was documented. Every edge case was dragged
into the light and argued until it either failed or proved it could survive. We stopped
when the models stopped disagreeing—not because they were perfect, but because
they no longer hid anything from us. At that point, continuing would not have made it
safer. It would only have delayed the moment when responsibility had to move on.

I remember when this bird was lines on a napkin and a room full of people saying
“probably.” Over the years, probably was burned out of it piece by piece. Anything
that could fail ambiguously was redesigned. Anything that could fail gracefully was
allowed to. Anything that could fail silently was not tolerated. There are systems here
whose sole purpose is to confirm that other systems are still telling the truth.
Redundancy is not optimism; it is respect for reality.

I hope it is never used. That hope is genuine, and it coexists cleanly with readiness.
If the day comes, it will not be because we rushed or cut corners or believed our own
press. It will be because the world asked a question that only this could answer.
When it leaves this bay, it stops being an engineering project and becomes a fact of
history. I have no illusions about that. I signed off anyway.