British Airways said on Wednesday afternoon that its flights were returning to normal after a major systems outage caused disruptions, according to Reuters.
It added that there could be "some knock-on operational disruption issues".
The company cancelled more than 100 flights and delayed dozens of others on Wednesday.
The IT failure — the latest in a series of similar problems at the airline — crippled check-in desks and left ground staff unable to dispatch flights.
Short-haul flights to and from the airline's bases at London Heathrow and London Gatwick were worst-affected, while many long-haul flights were delayed.
“We are experiencing some systems problems this morning which are affecting check-in and flight departures,” the airline told customers, urging them to “allow extra time at the airport."
Many passengers had already boarded and were waiting to take off when the problems began early on Wednesday.
Tens of thousands of customers were affected when the airline suffered a total systems outage lasting several days in 2017.