Flights into and out of the United Kingdom have been hit by technical problems at the NATS Swanwick control centre.
UK airspaces remained open, the air traffic control service said, but there would be limits on capacity while the problems were addressed.
“To maintain safety NATS is restricting the number of aircraft flying across the south of England and those taking off from airports,” read a statement.
“We regret any inconvenience this may cause however our first priority will always be the safety of the flying public.
“NATS is taking every step to restore services and has contingency plans in place to minimise any disruption.”