WASHINGTON - The U.S. air safety agency Monday confirmed that the air traffic control system surrounding Los Angeles was shut down last week after data from a U-2 spy plane’s flight plan scrambled the system’s software. In a statement, the Federal Aviation Administration said its software at an air traffic control facility north of Los Angeles ‘experienced problems while processing a flight plan filed for a U-2 aircraft that operates at very high altitudes under visual flight rules.’  A backup system was employed Wednesday afternoon to help guide  flights already in the air, though hundreds of planes scheduled  to fly to and from regional airports in Southern California and  Las Vegas were affected, according to NBC News. The U-2 plane, a Cold War relic, flies at around 60,000 feet, but the FAA said a  computer misjudged its altitude and tried to reroute the plane to 10,000 feet. ‘The computer system interpreted the flight as a more typical low altitude operation, and began processing it for a route below  10,000 feet,’ the FAA said. ‘The extensive number of routings that would have been required to de-conflict the aircraft with lower-altitude flights,’ said the FAA, ‘used a large amount of available memory and interrupted the computer’s other flight-processing functions.’ The spy plane’s altitude and route apparently overloaded a computer system called ERAM, which generates display data for air-traffic controllers. Back-up computer systems also failed. The plane is the same type of aircraft that flew high-altitude spy missions over Russia (then the Soviet Union) 50 years ago and more recently Afghanistan. The FAA said that it was 'investigating a flight-plan processing issue' at the L.A. Air Route Traffic Control Center. A U-2 plane was involved in an international diplomatic crisis in May 1960 when the Soviet Union shot down an American U-2 spy plane in Soviet air space and captured its pilot, Francis Gary Powers. The plane had taken off from Peshawar, and drew a sharp warning from Soviet Premier Nikita Khrushchev that Moscow might bomb the Pakistani city.