Working Up

by Dwayne Phillips

If a system fails at one boundary, it will probably fail at another boundary. Hence, if you find a boundary failure, start looking for other boundary failures while you still have a chance at prevention instead of correction.

A few years back I had a problem with my van. I couldn’t reliably turn on the headlights. That was a bad situation, especially after dark. I found myself sitting in a parking lot flipping the headlight switch over and over until the lights finally illuminated.

Then one night, I found that I couldn’t turn the headlights off. Again, that was a bad situation as leaving the headlights on all night would drain the battery and so on. Then it hit me:

boundary condition failures

The headlight switch failed at one boundary – turn lights on – then it failed at another boundary – turn lights off. My headlight switch was a classic example of a system that worked well in a “sweet spot” or “sweet range” of conditions, but had difficulties at the boundaries or edges.

Now consider a recent project I worked. Some weeks we had nothing to do – extremely light work. That was a boundary condition failure in planning the work for the project. Think about the other boundary condition. Well, I didn’t have to think about it much as the next week we had 80 hours worth of work. That was another boundary condition failure in planning the work for the project.

Hmm, a headlight switch and planning the work for a project. These two things had nothing in common except for boundary condition failures.

Time, and more keystrokes, would allow me to relate more examples of boundary condition failures. A lesson to draw from these examples is:

If your system has a boundary condition failure, start searching around the boundaries for other failures

Boundary condition failures bring more pain than other kinds of failures – at least they have in my life. This is because the boundary conditions don’t happen often, but usually happen at critical points in time – like when you are sitting in a dark parking lot and you can’t turn on the headlights.