The primary air traffic control system around Los Angeles shut down last week because data from the a U-2 spy plane's flight plan confused software that helps track and route aircraft around the region, the Federal Aviation Administration said Monday. When the system failed Wednesday, a backup helped safely guide flights already in the air, but hundreds of planes across the nation headed for Southern California were ordered not to take off as an air traffic control facility about 40 miles north of Los Angeles effectively rebooted. The problem had nothing to do with spy-related signals sent by the Cold War-era plane. The plane flies at around 60,000 feet under "visual flight rules." According to the FAA, a computer perceived a conflict between the altitude and the use of visual flight rules, and began trying to route the plane to 10,000 feet. The number of adjustments that would need to be made to routes of other planes throughout the area overwhelmed the software. "The extensive number of routings that would have been required to deconflict the aircraft with lower-altitude flights used a large amount of available memory and interrupted the computer's other flight-processing functions," the FAA said in a statement. via SFGate.