A U-2 spy plane, used since the days of the Cold War, apparently triggered a computer system malfunction at a California air traffic control center that led to flight delays April 30 at several airports in the southwestern region of the country and kept planes headed into the area from other parts of the country grounded.

The computer problem, as reported by NBC News May 3, occurred at a Federal Aviation Administration facility in Palmdale at around 2 p.m. and hampered travel for tens of thousands of arriving and departing passengers at Los Angeles International Airport, one of the busiest in the country, as well as Bob Hope Airport in Burbank, John Wayne Airport in Santa Ana and McCarran International Airport in Las Vegas, Nev., unnamed sources said.

The Federal Aviation Administration, which operates the L.A. Air Route Traffic Control Center, has released few details on the nature of the problem that caused its officials to halt flights, according to the NBC story.

Computers at the facility are programmed to keep commercial airliners and other aircraft from flying into each other. The U-2 in question was reportedly flying at 60,000 feet, but the computer system was apparently acting to prevent it from colliding with planes that were in fact miles beneath it.

Although the specific cause of the mishaps has not been announced, the spy plane's altitude and route seems to have overloaded the En Route Automation Modernization computer system, which generates display information used by air-traffic controllers.

Sources confirmed the ERAM back-up system also failed.

The FAA, as a result, had to stop accepting flights into the airspace managed by the L.A. center system and had to issue a nationwide ground stop that lasted for about an hour and affected thousands of travelers.

There were 27 cancellations of arriving flights at LAX, as well as 212 delays and 27 diversions to other airports.

While 216 departing flights were delayed, 23 departing flights ended up being cancelled.

The FAA said in a statement to NBC News it was "investigating a flight-plan processing issue" at the L.A. control center, but did not explain the reasons for the computer glitch, nor did it confirm it was related to the U-2's flight.

"FAA technical specialists resolved the specific issue that triggered the problem on Wednesday, and the FAA has put in place mitigation measures as engineers complete development of software changes," the agency announced. "The FAA will fully analyze the event to resolve any underlying issues that contributed to the incident and prevent a reoccurrence."

Sources told NBC News that the plane following a Defense Department flight plan was indeed a U-2, which the U.S. Air Force is still flying but plans to retire within a few years.