Monarch’s problems have been building for some time.
Terrorist attacks in Egypt and Tunisia and unrest in Turkey dented demand for tourism to those destinations, weighing on the carrier’s results. That forced the airline to rely more on routes to popular vacation spots in southern Europe, such as Spain, where it faced stiff competition.
Monarch was founded in 1968 and operated flights to 40 destinations from Britain, as well as providing tour packages. It employed about 2,750 people, according to the company’s website.
Greybull Capital, a London-based investment firm, took a controlling stake in the airline in 2014 and was forced to inject capital into the carrier last year.
“We are very sorry that we have not been able to turn around the Monarch Group, and for all the inconvenience and distress that this administration will cause customers, employees and the many people who are associated with Monarch,” a Greybull spokesman said on Monday.
In recent weeks, the airline had been negotiating with the Civil Aviation Authority, a British regulator, over an extension of its Air Travel Organizer’s License, which it needed to continue to sell vacation packages and to operate flights.
Monarch’s abrupt collapse has forced the Civil Aviation Authority to charter aircraft to help about 110,000 travelers stranded abroad return to Britain. A spokesman said that the regulator expected to coordinate about 700 flights over the next two weeks. The first flights arrived early Monday.
In a statement, Chris Grayling, the British transportation secretary, described the effort as “the biggest ever peacetime repatriation.”
“This is an unprecedented response to an unprecedented situation,” Mr. Grayling said.