During a recent business trip to Boeing's Everett, Washington factory, I noticed several 747 and 777 airliners being assembled. Before the engines were installed, huge weights were hung from the wings to keep the planes balanced. The solid-steel weights were bright yellow and marked, "14,000 lbs."

But what I found particularly interesting was some stenciling I discovered on the side of each weight. Imprinted there was the warning: "Remove before flight."