London: Computer problems are causing delays for British Airways passengers worldwide, the airline has said, reports BBC.
The carrier apologised for the "global system outage" and said it was "working to resolve the the problem as quickly as possible".
Heathrow Airport said it was "working closely" with BA to solve the issue.
It is not known how many flights are affected but passengers have reported issues with flights to and from Heathrow, Gatwick and Belfast.
The problems mean parts of BA's website are unavailable and some travellers claimed they could not check in on the mobile app.
BA aircraft landing at Heathrow are unable to park up as outbound aircraft cannot vacate the gates, which has resulted in passengers being stuck on aircraft.
Journalist Martyn Kent said he had been sitting on a plane at Heathrow for 90 minutes. He said the captain told passengers the IT problems were "catastrophic".