http://www.nytimes.com/2014/12/13/world/europe/london-air-traffic-glitch-closes-airspace-and-disrupts-flights.html 2014-12-12 19:43:40 London Air Traffic Glitch Closes Airspace and Disrupts Flights A computer problem at an air traffic control center in Swanwick disrupted flight schedules at Heathrow, one of the world’s busiest airports. === LONDON — London’s airspace was sharply restricted for hours on Friday afternoon at the beginning of a busy pre-Christmas weekend because of a computer failure at one of Britain’s two air-traffic control centers, British authorities said. The agency known as NATS, in charge of air traffic control, said “a technical problem” had affected the control center in Swanwick, England, at about 3 p.m. and that airspace would be restricted while the problem was resolved. While officials at London’s Heathrow Airport, one of the world’s busiest, said that the NATS center in Swanwick had suffered a power cutoff, others described the problem as a glitch in the computer software that sequences flights for takeoff and landing. There was no official indication of how long traffic would be disrupted, with officials saying that they hoped to restore the service by 7 p.m. local time. Express trains from London to Heathrow were suspended. At about 4:30 p.m., NATS announced that the computer problem had been fixed and that it was in the process of normalizing operations. “However, it will take time for operations across the U.K. to recover so passengers should contact their airline for the status of their flight,” the agency said, apologizing for “any delays.” Heathrow Airport reported delays, and Gatwick Airport said that while flights were continuing to land, departing flights were halted for a time. David Whitely, a spokesman for Gatwick, said that Friday nights were normally not so busy there. Flights farther out from London airports were expected to be diverted to other airports, like the Manchester Airport, which remained open. The Swanwick center also controls flights over the Stansted, Luton and London City airports, all of which were affected by delays. The NATS control center said that “every possible action is being taken to assist in resolving the situation and to confirm the details.” NATS is a public-private partnership company that provides air navigation services at Heathrow and a dozen other British airports. Last December, a computer problem at Swanwick took 12 hours to fix. The other NATS control center is in Scotland. Marianna Panizza, a Heathrow Airport spokeswoman, said the incident was expected to ground close to 50 flights for every hour of airspace restriction. Heathrow handles 72 million passengers a year, and Gatwick 35 million. Most passengers at Heathrow were not initially aware of the problem. Vicky Lane, a passenger on a grounded flight from London Gatwick to Dublin, told the BBC, “We’ve been stuck on a Ryanair flight” for over an hour. “The doors are open and we’re really cold. I’m not sure when we will be leaving.” At Heathrow, passengers on United Airlines Flight 941 to Newark were told about the computer problem as they boarded at 3:30 p.m. local time, The Associated Press said. United’s staff at the gate said the plane would be loaded and head to a runway in the hope that the computer problem would be fixed. The Swanwick center has had numerous problems with software and reliability since it opened in 2002, six years late. In 2004, a computer problem grounded scores of flights across Britain. An even more serious The 2013 failure at Swanwick was particularly bad because it came at the beginning of the holiday season. After calm was restored, NATS chief Richard Deakin called that failure a “one-in-10-year event.”