Transatlantic flights were delayed on Saturday due to a fault in an air traffic control system, British officials said.
Flights from London Heathrow airport to the United States were worst affected with some delays of up to two hours, said a spokeswoman for NATS, which is in charge of air traffic control in British airspace.
"At 0800 this morning (0700 GMT), a fault developed within the Shanwick Automated Airtraffic System which manages Oceanic airspace across the North Atlantic from the Prestwick centre in Scotland," NATS said.
"NATS has imposed restrictions on aircraft entering Oceanic airspace. NATS has reverted to manual systems which means reduced capacity leading to some delay. There is no safety implication."