Last week, a 1950s Cold War spy plane -- the Lockheed U-2 Dragon Lady -- caused hundreds of planes across the US to be grounded for an hour, and delaying hundreds more that were already airborne. The U-2, which was just minding its own business at an altitude of 60,000 feet above southern California, triggered a software bug that caused the FAA's air traffic control system to "overload" and shut down. The backup system also failed, presumably for similar reasons. The beautiful irony is that both the plane and the air traffic control software were created by Lockheed. How did an ancient plane that has been trawling the skies for almost 60 years cause such a catastrophic failure?