The first of 155,000 British tourists flew home Monday after the collapse of travel agent Thomas Cook.
The Civil Aviation Authority (CAA) coordinates the largest peacetime repatriation after the tour operator "ceased trading with immediate effect".
The government of Thomas Cook threatens 22,000 jobs worldwide, including 9,000 in the UK.
Chief Peter Fankhauser said the collapse was "a matter of deep regret".
Thomas Cook, whose roots go back to 1
Around 16,000 holidaymakers were booked to return on Monday, and the authorities hope to bring at least 14,000 of them home on charter flights. – chartered 45 jets to bring customers from countries such as Central America and Turkey home. It will fly 64 routes on Monday in a company called Operation Matterhorn.
Operators like easyJet and Virgin have delivered some aircraft with jets that came from far away places like Malaysia.
All Thomas Cook holidays are now canceled and customers must apply for compensation through the government's Atol system or through their credit card or insurance companies.
Some passengers who want to come home reported queues and disruptions at airports others complain that they were left in the dark about what happens next.
Customers looking for information can visit the CAA's dedicated Thomas Cook website. Those wishing to return to the UK within the next 48 hours or having problems with their accommodation or needing special assistance may call in the United Kingdom at 0300 303 2800 or from abroad on +44 1753 330 330.
What is the government doing?
Transportation Minister Grant Shapps defended the attempt to give Thomas Cook no rescue.
"I'm afraid he would have kept them afloat for a very short period of time, and then we would have been able to do that by any means repatriate people," he said on BBC's "Today." ,
The company's high debts and high-street business made it a poor survival candidate.
Overall, Operation Matterhorn will cost the taxpayer about £ 100 million, he added.
Chancellor John McDonnell told the BBC that the government should have saved Thomas Cook "if only to stabilize the situation a real plan for the future of the company could be tackled".
Prime Minister Boris Johnson promised to help stranded travelers, but also questioned whether the company's directors were adequately motivated to resolve such issues.
"I feel totally devastated"
Ruth Morse from Halesowen, West Midlands, was supposed to marry her partner in Cyprus on October 8, but now the wedding is in doubt.
She booked the entire event over Thomas Cook, including the decoration, the cake, the wedding venues and a private bar.
And of the 44 guests present, around 25 booked their flights and accommodations through the travel agency.
"At the moment, Thomas Cook was not in touch, so we're in the dark," says Ruth.
"I know we are protected by Atol, but I'm not sure what we bought from third parties through Thomas Cook, like the decoration, it costs me £ 4,000."
Ruth says she planned it. "Dream wedding" for two years. What makes it twice as hard is that much of the money she spent came from family members, including her mother and her deceased brother Ben, who was murdered in 2017's dream day, "she says.
" We're getting married but I will not make them abroad again because I lost faith. I feel totally devastated by all this. "
How will vacationers get home?
While an estimated 150,000 Britons are affected by the collapse of Thomas Cook, the company has up to 450,000 overseas clients, some of whom
In Germany one of Thomas Cook's main markets, insurance companies, will help organize the reaction to the collapse.
British customers are brought home as close as possible to their booked return date, as reported by the Department for Transport (DfT).
Customers can book special flights for free or book a flight on another scheduled airline. Details of each flight will be posted on a dedicated website as it becomes available.
The DfT added that a "small number" of passengers may have to book their own flight home and reimburse the costs.
Customers were asked not to cut back on their holiday or to drive to the airport without checking the website. Further information on the return journey.
The CAA also contacts hotels that host Thomas Cook customers who have booked as part of a package to let them know that the cost of their accommodation is covered by the Air Travel Trust Fund and the licensed travel agent program (Atol). ,
Tim Johnson, Policy Director of the CAA, told BBC News customers whose holidays were canceled would be notified how to claim a refund on the site. Business Secretary Andrea Leadsom said she will write to the bankruptcy service asking her to investigate the circumstances surrounding the liquidation of Thomas Cook.
The investigation will also look at the behavior of top directors, who have received a combined £ 20 million in salaries and bonuses since 2014.
A cabinet spokesman said: "People will rightly consider the amount of premiums for some of the directors and have serious concerns."
"There is a bigger problem in connection with the collapse of businesses and the payment of directors, and we see it more generally as a government. "
22,000  Worldwide jobs at risk
9,000 Vulnerable jobs in the UK  150,000 British tourists must be repatriated
600,000  customers in total abroad
34 aircraft owned (Airbus A321 and A330)
Source: Thomas Cook
What happens to the Employees?
In some of Thomas Cook's stores, employees have already met representatives of the company's administrators who have told them that they have been fired
Jobs may also be lost at the airline of the tour operator and in their engineering department.
Some employees continue to be employed, but there is no specific number.
Thomas Cook stores across the UK are not responsible for opening on Monday.
What about the international activities of Thomas Cook?
Currently, the Indian, Chinese, German and Nordic subsidiaries of Thomas Cook continue to trade as usual.
This is a legal condition. You are deemed to be separate from the UK parent and are outside the jurisdiction of the UK public official.
However, they share services such as airplanes and IT with their parent company and need to conclude rescue deals in the US In the coming weeks, trade has continued.
What went wrong?
Thomas Cook had signed a £ 900m rescue contract in August under the leadership of his largest Chinese shareholder, Fosun.
Fosun said in a statement, "We express our deepest sympathy to all concerned."
The holiday company has held talks with lenders all Sunday to secure additional funding and rescue the business, but to no avail.
Thomas Cook has blamed a number of problems for his problems, including political unrest in holiday destinations such as Turkey, the prolonged heatwave of last summer, and customers postponing their vacation bookings due to Brexit.
Speaking to BBC News from Manchester Airport, travel expert Simon Calder said Thomas Cook was "not ready for the 21st century."
"Now anyone can pretend to be a travel agent, they have access to all the seats, hotel beds and car rentals in the world and can put things together themselves."
Mr Calder, tour guide at The Independent, added that planes arrive at the airport shortly after While the company shut stores to cut costs, it closed 21 in March and still had more than 500 major outlets costs compared to online competitors.
In another indication for its slow progress in improving its finances, dividend payments to investors were discontinued only in November.