British Airways resumes some flights but delays are expected

Flights from London's Heathrow and Gatwick airports have resumed after a massive IT failure caused chaos, but passengers face further delays and cancellations.

British Airways told travellers to check the status of their flights before coming to the airports and urged those without a confirmed booking to stay away.

It said travellers were not being admitted at Heathrow Terminal 5 until 90 minutes before their flight is scheduled to take off - a bid to ease overcrowding at terminals.

BA said on Sunday evening that many of its IT systems were now back up and that at Gatwick it was running a near-full operation.

On Heathrow, it said: "At Heathrow we are aiming to fly all our long-haul services but the knock-on effects of yesterday's disruption are causing some delays and some short-haul cancellations."

Heathrow said it expected more disruption on Sunday.

All flights were cancelled from London's Heathrow and Gatwick airports on Saturday, leaving thousands of passengers stranded at the start of a bank holiday weekend.

"Following a worldwide British Airways' IT system issue yesterday, delays and cancellations of British Airways flights are expected today," Heathrow said in a statement.

"All passengers whose flights were cancelled yesterday should not travel to the airport today unless they have already rebooked onto another flight."

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Passengers were reporting congested terminals and long queues, with some venting continued frustration on social media or inquiring about lost luggage.

Adding to the confusion, some passengers have been travelling to the airport, ignoring BA's advice, but have been turned away at terminals unless they could show a valid boarding pass.

Alex Cruz, the airline's chairman and CEO, issued a video message on Twitter to reassure passengers about their lost luggage and apologise.

He said Gatwick was running at almost full operational capacity, but with delays; at Heathrow the knock-on effect brought delays on long-haul flights and delays and cancellations on short-haul ones.

"I know this has been a horrible time for customers. Some of you have missed holidays, some of you have been stranded on aircraft, some of you have been separated from your bags. Many of you have been stuck in long queues whilst you waited for information," he said.

"On behalf of everyone at BA I want to apologise for the fact that you had to go through these very trying experiences."

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The airline said earlier on Sunday it was hoping to operate a "near-normal schedule" but it could face a hefty compensation bill given the scale of the disruption.

Mr Cruz said passengers whose flights were cancelled could rebook for alternative dates any time until the end of November - or have a full refund.

All of BA's check-in and operational systems were affected by the global IT outage, including customer services phone lines and the facility used for re-booking flights.

The problems also created a knock-on effect on BA's operations around the world.

The airline blamed the outage on a power supply issue and said it saw no evidence of a cyberattack.

Some experts expect the disruption to last several days, as planes and aircrew are returned to their positions and the backlog of passengers is cleared.

Air industry consultant John Strickland said: "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."

Malcolm Ginsberg, editor in chief at Business Travel News, said: "This is a very, very serious situation, one that will not be solved overnight, even once they get the technology aspects of it done - it's going to be three or four days.

"There's only full aircraft at this time of year and there will be aircraft in the wrong positions."