Uncle Bill's Helicopter

“On September 23rd, 1999, the Mars Climate Orbiter, after travelling from earth to mars, missed its re-entry to the atmosphere by 143 kilometers, and burned to a crisp. Why? One engineering group used english units, the other used metric. 3 years of labor. Toast. They’d made a big mistake. They’d screwed up. Email to engineering: Clearly communicate essential facts. Otherwise, spaceships turn to smoke and ash. If you can’t convert between meters and feet, don’t leave the United States, or the planet!” Bill TahtUncle Bill’s HelicopterTaht.net)