The system outage forced British Airways to cancel at least 60 flights, disrupting thousands of passengers.
The IT outage has crippled the airline’s operations, causing massive delays for departures and arrivals, and has also affected the airline’s website and booking system.
It is the latest in a series of system failures in recent years, including some that caused chaos that lasted for days and cost the airline millions of pounds in damages.
Dozens of short-haul flights have been cancelled, as well as some long-haul flights, ahead of what is expected to be Heathrow’s busiest travel day at the start of the holiday weekend and midterm break.
“Our teams are working hard to resolve the technical issue we encountered this afternoon,” the airline said. “We apologize for this inconvenience and thank our customers for their patience.”
Long lines have begun to form at Heathrow as passengers search for alternative flights, while many who land at the airport are unable to disembark.
Vienna, Dublin, Dusseldorf, Edinburgh, Venice, Rome, Hamburg, Aberdeen and Milan are among the affected destinations from Heathrow. Boston, New York JFK and Mumbai are the long-distance cancellations.
At Heathrow, notices were recorded asking passengers on canceled flights to leave the airport and book a hotel room for a refund later.
BA flights at London Gatwick were also delayed.
The outage also briefly disrupted the airline’s booking system, leaving customers unable to check in for flights or access their existing reservations or accounts.
Earlier this year, British Airways returned to profitability for the first time since 2019.
Parent company IAG, which also owns Iberia, Aer Lingus and Vueling, made £7.9m of operating profit in the first quarter of 2023 – compared with a loss of £660m over the same period in 2022 — and the company predicts a bumper summer.
BA said customers should still check-in as usual for their flights.
Heathrow Airport said: “British Airways has experienced a technical issue that is affecting a number of British Airways departures and arrivals. For flight status, please contact British Airways or your travel provider.”