A British Airways Airbus A380, on final approach into Heathrow Airport, flies over the top of a chimney, as visitors look out from Lift 109, at Battersea Power Station, in south London, on January 18, 2023, during sunset. (Photo: AFP)

British Airways canceled dozens of flights on Friday due to computer problems, disrupting the plans of thousands of travelers at the start of a busy holiday weekend.

Most of the 42 affected flights were on short-haul routes to and from Heathrow, Europe's busiest airport. Computer issues on Thursday caused planes and crew to be out of position Friday, which was expected to be the busiest day for U.K. air travel since before the coronavirus pandemic.

Other flights were delayed, as some passengers were unable to check in online.

"We're aware of a technical issue, which we have been working hard to fix," the airline said on its website.

Travel is expected to be especially busy over the next few days as a three-day weekend coincides with the start of a weeklong holiday for most schools in Britain.