Some years ago we made monitoring systems and were asked to do one for a large boiler. The plant engineers emphasized that 5-digit accuracy was crucial, as even the smallest error could mean millions in operating costs.

George and Charlie were in charge of data collection and A/D conversion. Both guys were very reliable with many years of experience, so we had no worries in that regard.

The customer insisted on an unusual full pre-installation demo at our factory, squeezing our normal schedule. Two weeks before the demo Charlie took a new job in another country, leaving George to finish up. But the week before the test George died in a boating accident. We were sure he was finished with the system, and the numbers looked right, so we went ahead with the demo. The system was then installed and went through certification, which the plant engineers signed off on.

Years later I bumped into Charlie, and we got to talking. It turns out the system was not finished after all. The least-significant BCD digit from A/D conversion wasn't working right, so to meet the deadline Charlie dummied it in by software with cleverly manipulated random numbers for a realistic demo, until George could fix the hardware problem on-site before final testing. Obviously, George never made it to the site.

As far as anyone knows, that's how the system ran until it was decommissioned. The customer never complained, so apparently accuracy wasn't all that important after all.

Simon S., Melrose, Mass