“Flights are operating and we’ll finish our schedule this evening as planned. No cancellations. Some delays. All of our critical operations are running,” BA said in a statement.
Downdetector, a website that logs complaints with websites that are not working, indicated a sharp increase in problems with the BA site after 17:00.
It is not clear how widespread the disruption is, but it is reported to have affected flights globally, as well as some domestic UK flights.
The travel expert and journalist Simon Calder estimated the problems could be affecting tens of thousands of passengers, although the delays seem to be limited to one to two hours for affected flights.
One passenger wrote on X that they were “being made to stand on the tarmac in a very cold Verona waiting for an already delayed flight”.
Others said they were trying to check in for flights and the “systems are down” or that technical problems had prevented them from booking flights.
Sources within the airline suggest the situation is being brought under control, but there are concerns that delays this evening could have a knock-on effect on Tuesday’s flights.
Some travellers commenting on social media said they had been told that pilots were unable to generate loading data for their aircraft and have been struggling to get through to colleagues by phone.
A spokesperson for Heathrow Airport said it was aware of the technical problems at BA, but that its own systems were operating normally.
It is not the first time BA has faced severe disruption due to an IT failure. In May last year, flights were grounded. A similar thing happened in spring 2017, disrupting Bank Holiday plans, and in February 2020.