The British government said Tuesday that a breakdown at the nationwide air traffic control system that saw hundreds of flights delayed and canceled was not caused by a cyberattack.
Transport Secretary Mark Harper said the problem was caused by a “technical fault” at flight control operator National Air Traffic Services. The company said the outage had hit its ability to process flight plans automatically, meaning that for several hours the plans had to be input manually, a much slower process that meant fewer flights could take off and land.
Harper told the BBC that “it is going to take some days to get people back to where they should be.”
The problem hit on a late-summer holiday Monday that is one of the busiest days of the year for air travel. Aviation analytics firm Cirium said that by Monday afternoon, 232 flights due to leave U.K. airports and 271 arriving flights had been canceled.
Dozens of flights were canceled at Heathrow, Europe’s busiest air hub, which warned of “knock-on impacts.” At least 32 departures from Heathrow were canceled on Tuesday, and 31 arrivals axed.
Gatwick, London’s second-busiest airport, said it planned to operate a normal schedule on Tuesday, but advised passengers to check with airlines before traveling to the airport.