British Airways is now operating a full flight schedule after an IT failure saw the airline cancel thousands of flights over the bank holiday weekend.
“Our IT systems are now back up and running and we will be operating a full flight schedule at Heathrow and Gatwick,” the airline said.
But it warned it “may take some time” to reunite travellers with their bags.
BA chief executive Alex Cruz has blamed a power surge for the disruption, which affected 75,000 people.
In a statement on Monday, the airline apologised again for the “frustration and inconvenience” to passengers and said it was continuing to get people reunited with their luggage “as quickly as possible”.
The airline also admitted that it was aware some passengers were unable to file a delayed bag report on its website.
Thousands of BA passengers worldwide are still without their bags and have been bombarding the airline’s lost luggage phone lines, website and social media feeds.
British Airways has also been criticised on social media for directing some passengers towards a premium-rate phone line that costs up to 55p a minute from a mobile device.
In response, the airline says customers can add any phone charges into claims they submit and it will look at them.
It also says there are free or local rate alternative phone numbers for passengers who want to contact them
Despite the knock on effect of the incident lasting three days, Mr Cruz said the hardware problem was restored “after a few hours”, and promised the company would “make sure that it doesn’t happen again”.
In his first interview since the systems failure, he said: “There was a power surge and there was a back-up system, which did not work at that particular point in time.”
He told the BBC this had affected “all the operating of our systems – baggage, operations, power processing”.
The GMB union has blamed the problem on technical staff being outsourced from the UK to India.
But Mr Cruz said there had been no redundancies or outsourcing in this area, adding that there had been “locally hired” staff attending to the maintenance and running of the infrastructure.
The focus is now likely to shift towards the financial impact on the airline.
BA is liable to reimburse thousands of passengers for refreshments and hotel expenses, and travel industry commentators said the cost to the company – part of Europe’s largest airline group IAG – could run into tens of millions of pounds.
Shares in IAG, which also owns Iberia and Aer Lingus, were down 3% in morning trading in London. However, the stock has risen by more than a third this year, valuing the company at almost £12.5bn.
Neil Wilson at ETX Capital said IAG chief executive Willie Walsh had serious questions to answer about cost-cutting: “A master of slicing back the fat, the outage has investors worried that he’s gone too far.”
George Salmon, a Hargreaves Lansdown analyst, said: “The whole sorry episode has undeniably put a dent in BA’s reputation for delivering a premium service, and the worry for shareholders is that this unquantifiable impact could have longer-term consequences.”
Davy analyst Stephen Furlong said the cost to the carrier of cancelling one day of operations was about £30m.