More than a third of British Airways flights from Heathrow have been cancelled as disruption to passengers enters a second day.
The airline was hit by a worldwide computer system power failure on Saturday, causing cancellations and delays for thousands of passengers.
All long-haul services will fly from Heathrow, but with delays, BA said.
The airline urged people to check the status of flights before travelling to the airport.
Heathrow Airport is providing an updated schedule on its website, as is Gatwick, where Sunday departures are delayed but not cancelled.
BA advised passengers not to arrive at the airport too early, as people are not being admitted into Terminal 5 until 90 minutes before departure.
The airline apologised to customers for the issue, which is thought to have been caused by a problem with the IT system’s power supply.
In a statement released on Sunday, chief executive Alex Cruz said: “I know this has been a horrible time for customers. We’re not there yet, but we are doing our very best to sort things out for you.”