Johns Hopkins APL sonar tow cable pad-eye failure

Tom's worked example of system-one heuristic ("if the metal deformed before the weld broke, the weld was good") versus system-two analysis (cable strain calculation, 150,000-psi load estimate). Used to make the broader point that engineering judgment is the interaction between fast pattern recognition and slow quantitative confirmation.

There are heuristics we develop, and I talked about the one I used when I was looking at faculty resumes: if it took them too long to graduate from graduate school, they're not going to be very productive as a faculty member. I'll show you another heuristic that I used, because I haven't been giving you very many of the engineering stories. A number of years ago I was asked to evaluate why a pad eye had failed. I'll show you what a pad eye is in a second.