BA resumes some flights but delays are expected

Some flights from London's Heathrow and Gatwick airports have resumed after a massive IT failure caused chaos, but further delays and cancellations are expected.

The airline told travellers to check the status of their flights before coming to the airports, and Heathrow said it expected more disruption on Sunday.

All flights were cancelled from London's Heathrow and Gatwick airports on Saturday (Shenzhen: 002291.SZ - news) , 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," the airport said.

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

The airline said earlier on Sunday it was hoping to operate a "near-normal schedule" and apologised for the disruption.

"We are continuing to work hard to restore all of our IT systems and are aiming to operate a near normal schedule at Gatwick and the majority of services from Heathrow on Sunday," BA said in a statement.

"We are refunding or rebooking customers who suffered cancellations on to new services as quickly as possible," it said.

"We are extremely sorry for the huge disruption caused to customers."

On Saturday planes were grounded on runways and thousands of passengers were queuing for hours as terminals at both Heathrow and Gatwick were "extremely congested".

Many complained about a lack of information at the terminals, and some who did manage to depart often did so without luggage.

All of BA's check-in and operational systems were affected, 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 said it had experienced a "global systems outage" blamed on a power supply issue and saw no evidence of a cyberattack.

:: Passengers describe airport pandemonium

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."