British Airways has said it is aiming to operate a “near normal schedule” at Gatwick and the “majority of services” from Heathrow on Sunday after a global IT crash crippled the airline.

Thousands of passengers were left stranded after scores of planes were grounded by the major systems failure believed to have been caused by a power supply issue.

The airline said its engineers were “continuing to work hard” to restore its services and it hoped most UK flights would resume on Sunday.

However experts predict the disruption could continue for several days and BA is facing huge compensation costs after all its flights from Gatwick and Heathrow were cancelled on Saturday.

As IT teams tried to fix the system:

:: There were chaotic scenes at Gatwick and Heathrow as people tried to make their way overseas for the long weekend and half-term school holiday.

:: All of BA’s check-in and operational systems were affected by the issue, including the airline’s customer service phone lines and rebooking function.

:: The incident had a knock-on effect on BA’s operations around the world.

The Terminal 5 departure lounge at Heathrow airport after flights were cancelled(Emily Puddifer via AP)

:: BA chief executive Alex Cruz said the airline was “extremely sorry” for the “huge inconvenience” suffered by customers, especially families heading on half term holidays.

:: Travellers have been told to check the airline’s website and Twitter account for updates before setting off for the airport.

The glitch is believed to have been caused by a “power supply issue” and there is no evidence of a cyber attack, the airline said.

BA initially cancelled all flights before 6pm on Saturday but later announced that planes would be grounded for the rest of the day and warned passengers not to go to the airports.

It is feared that it could take days for services to return to normal and clear the backlog of passengers.

Air industry consultant John Strickland said the disruption could “run into several days” and added: “There’s a massive knock-on effect.

“Customers and from the airline’s point of view – manpower, dealing with the backlog of aircraft out of position, parking spaces for the aircraft – it’s a challenge and a choreographic nightmare.”

Several travellers at Heathrow told the Press Association they were not told their flights were cancelled until more than an hour after the airline put out a press statement announcing the decision.

Student Emily Wilson told the Press Association: “We were told (it would be) about three hours for collecting bags, that all compensation will have to be done online, and that we are unable to rebook flights now because of the system being down.”

At Gatwick frustrated passengers could be seen surrounding BA staff at the check-in as they handed out letters which apologised for the cancellations and gave details about how to claim for hotels, local transport and refreshments.

Customers who saw their flights cancelled are being refunded or rebooked on to new services and other options are available for those who no longer want to fly.