An IT problem at Heathrow caused disruption on Saturday night, a spokeswoman for the airport said, after travellers reported flight delays.
Some IT systems failed at around 20:50, causing delays in handling baggage and problems with the online live arrivals and departures service, she added.
The spokeswoman said the issue was later resolved.
A number of people took to social media to complain of problems, with some reporting "huge delays" at the airport.
British Airways said the problems affected all terminals.
A BA spokeswoman said: "Passengers are experiencing disruption as a result of issues with one of Heathrow Airport's IT systems.
"British Airways is working with the airport to resolve matters. Passengers should check with Ba.com regarding their flight."
A spokeswoman for Virgin Atlantic said six flights due to depart from Terminal 3 had been delayed by about 30 minutes.