By Dan Whitcomb
LOS ANGELES (Reuters) - An air traffic control glitch that caused hundreds of flight cancellations or delays across Southern California last week was triggered by a computer misinterpreting the flight path of a U-2 spy plane, the Federal Aviation Administration said on Monday.
A computer problem at an air traffic control center in Palmdale, California last Wednesday forced the delay or cancellation of more than 200 flights at Los Angeles International Airport.
Dozens of flights were also delayed at smaller airports across the region, as well as commercial airliners headed for Southern California from across the country.
"On April 30, 2014, an FAA air traffic system that processes flight plan information experienced problems while processing a flight plan filed for a U-2 aircraft that operates at very high altitudes under visual flight rules," FAA spokesman Lynn Lunsford said in a written statement issued by the agency.
Lunsford said the computer system misinterpreted the U-2 as a more typical low-altitude operation and became overwhelmed in trying to make sure that its flight path did not conflict with other air traffic in the region.
"The FAA resolved the issue within an hour, and then immediately adjusted the system to now require specific altitude information for each flight plan," he said, adding that the agency had also taken steps to increase the amount of flight-processing memory available in the computer system.
"The FAA is confident these steps will prevent a reoccurrence of this specific problem and other potential similar issues going forward," Lunsford said.
A Pentagon spokesman confirmed that the U-2 spy plane had flown over Southern California last Wednesday as part of a routine training mission but said he could not confirm that it was responsible for the computer glitch.
"The U-2 filed all the proper flight plan paperwork and was conducting its operation in accordance with those filings," Army Colonel Steve Warren said, adding that it was not unusual for the plane to be flying over the area.
Warren said the incident had not prompted the military to change the way it conducted such operations.
Bob Hope Airport in Burbank, California; John Wayne Airport in Santa Ana, California; and McCarran International Airport in Las Vegas were among other facilities affected by the order to keep planes grounded.
So were flights in other parts of the country that were bound for the wide swath of airspace in the southwestern United States managed by the center.
(Additional reporting by David Alexander in Washington, D.C.; Editing by Cynthia Johnston, Ken Wills and Eric Walsh)