The UK's Air Traffic Control operator says it has identified and fixed a technical issue that caused disruption today.
It says the problem was affecting the automatic loading of flight plans, so they had to be input manually.
The operator, NATS, says its working with airlines and airports to get through the affected flights as efficiently as possible.
Engineers are also watching the system closely while it returns to normal functions.
Junior Transport Minister Jack Chambers says it will have a knock-on effect on flights to and from Ireland.
The UK national air traffic control service @NATS is working to resolve a technical issue. UK airspace is not closed but @NATS has applied air traffic flow restrictions to ensure they can maintain safety. Please contact your airline for the very latest status of your flight. https://t.co/sOJC80avBY
— Dublin Airport (@DublinAirport) August 28, 2023
Ireland's aviation authority, Air Nav Ireland, says: "Flights between Ireland and UK airports, and flights travelling to or from Ireland that travel through UK airspace are experiencing significant delays.
"At this time, there is no certainty as to when flights will be back on schedule so passengers who are due to travel today should contact their airlines in the first instance to check if their flights are delayed."
Stuck on the tarmac in Liverpool for 45 mins so far due to system failure with air traffic control… pic.twitter.com/JRO89TRLIB
— Alex Rowley (@AlexRowley04) August 28, 2023
