One of the biggest misconceptions about engineering is that experienced engineers know all the answers. In reality, experienced engineers have simply seen more ways that things can fail.
Where my growth actually came from
- Hardware that did not behave like the datasheet promised.
- Samples that were not representative of production.
- Production variation that was larger than anyone expected.
- Requirements that changed halfway through a project.
- The theoretically correct solution that was not practical.
These situations taught me far more than the projects that worked perfectly the first time.
Three failures and what each one taught
The datasheet that was technically true
A light source was specified as "stable to 1%". True - after a 30-minute warm-up, which was mentioned nowhere. The first half hour of every shift produced drifting gray values and a wave of false rejects. Since then, every stability number I read gets the question: stable from when, and under what conditions?
The perfect lab system
A measurement system achieved beautiful repeatability on the bench. On the line, results wandered by 5x the lab spread. The cause was a vibration from a neighboring machine with a cycle time that aliased against our capture rate, so it never showed up in short tests. Lesson: test in the real environment for at least one full production cycle of everything around you.
The clever algorithm nobody could maintain
I once replaced a chain of simple thresholds with a much smarter adaptive approach. It performed better - until the process changed slightly and it failed in a way nobody on site could diagnose. The simple version failed loudly and predictably; the clever one failed silently. Lesson: a solution the team can reason about beats a better one they cannot.
How to actually learn from failure
Failure only teaches if it gets captured. My rule is that every surprising failure earns a short written note: what happened, what we believed beforehand, what was actually true. The notes are embarrassing to write and incredibly valuable two years later.
The goal is not avoiding mistakes. The goal is learning faster than the problem changes.