LONDON (AP) -- Hundreds of flights were delayed or canceled at Britain's busiest airports Saturday after a technical glitch left the main air traffic control center unable to operate at full capacity for much of the day.
National Air Traffic Services, which controls England's crowded airspace, said it was having a problem switching between nighttime and busier daytime operations at its control center in Swanwick, southern England.
NATS spokeswoman Juliet Kennedy said the problem with an internal communications system was preventing staff opening new control positions to deal with busier daytime traffic, meaning the service was able to handle about 20 percent fewer flights than on a normal Saturday.
At about 7:30 p.m. (1930 GMT, 2:30 p.m. EST) -- about 12 hours after the disruption was reported -- NATS said the problem had been fixed and services were returning to normal.
Heathrow Airport -- Europe's busiest -- had delays of an hour or more on many departures, and canceled more than 200 arriving and departing short-haul flights.
London Stansted Airport said departing flights were delayed by up to four hours because of restrictions on air space and the flow of planes. Gatwick airport said 20 percent of flights were being delayed.
Spillover delays were reported across Britain and at Dublin airport in Ireland.
The European air navigation center, Eurocontrol, said 1,300 flights were severely delayed, 8 percent of the European daily total.
The British air traffic service normally handles up to 6,000 arriving and departing flights a day from its bases at Swanwick and at Prestwick in Scotland.
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