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 US Federal Aviation Administration said.
A computer problem at an air traffic control centre 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 on Monday.
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.
A Pentagon spokesman confirmed that the U-2 spy plane had flown over southern California last Wednesday but said he could not confirm that it was responsible for the computer glitch.