British regional airline Flybmi has cancelled all its flights and filed for administration, the airline has announced.
The company said it had been badly affected by rises in fuel and carbon costs and uncertainty over Brexit.
The East Midlands-based airline, which has 376 staff, operates 17 planes flying to 25 European cities.
Affected passengers have been told to contact their travel agents or insurance and credit card companies.
A Flybmi spokesman said: "It is with a heavy heart that we have made this unavoidable announcement.
"The airline has faced several difficulties, including recent spikes in fuel and carbon costs, the latter arising from the EU's recent decision to exclude UK airlines from full participation in the Emissions Trading Scheme.
"Current trading and future prospects have also been seriously affected by the uncertainty created by the Brexit process, which has led to our inability to secure valuable flying contracts in Europe."
The airline issued the following advice to those due to fly:
- People who booked directly with Flybmi should contact their card issuer to seek a refund.
- Passengers who booked via a travel agent or one of Flybmi's partner airlines should contact them to see what their options are.
- Those with travel insurance should see if they are eligible to claim for cancelled flights.
The Civil Aviation Authority also published advice for travellers.
Rory Boland, travel editor for consumer body Which?, said: "Some customers have claimed that tickets were being sold in the hours before the airline went bust, knowing full well those tickets would never be honoured, and passengers will rightly be outraged if this is proved to be the case."
One of Flybmi's domestic routes, linking Derry and Stansted, was subsidised by the government to boost trade and travel between Northern Ireland and the rest of the UK.
Several people use the flights for work and Derry Strabane Council said it was in emergency talks with the Department of Transport to seek a replacement airline on that route.
Very disappointing news that @flybmi have gone into receivership - Council would like to reassure the public that its officers & reps from @CoDerryAirport are in emergency talks tonight with UK Dept for Transport to urgently seek a replacement airline pic.twitter.com/zIohtlo4HQ— Derry Strabane Cncl (@dcsdcouncil) February 16, 2019
Richard Edwards, from West Sussex, on a skiing holiday in Austria with his wife and three children, told how they had experienced problems with their scheduled flight out to Munich.
He said: "We had gone through security at Bristol Airport when there was an announcement saying our flight had been cancelled.
"They laid on taxis to Heathrow and booked us on a Lufthansa flight to Munich.
"I don't know how we will get back yet. I'm not confident Flybmi will be able to sort it."
Great start to our holiday; en route with @Charlot53066691 and the family by taxi to Heathrow as our @flybmi from Bristol to Munich (which had previously been changed from Southampton) was cancelled with no explanation after we had gone through security! 😬😬😬— Richard Edwards (@RA_Edwards9) February 16, 2019
Durham University student Mary Ward found out her flight could be affected when her mother showed her a news alert.
Shortly afterwards Mary received a text from the airline: "URGENT: Important message for Flybmi customers. All flights are cancelled. Please go to www.flybmi.com for further details. Thank you."
She had been due to fly from Belgium to Newcastle but is not sure what she will do now.
"I paid £130 for my flight which it doesn't seem I'm going to get back - I don't know how I am going to get back to Durham," she said.
"I can't afford any of the flights or the Eurostar."
The UK regional airline Flybe tweeted to reassure some passengers who had confused the airline with the similar-sounding Flybmi.
We are very sorry to hear about the situation with the competing British regional airline Flybmi and our thoughts are with their employees during these difficult times. Flybe has nothing to do with Flybmi and our flights continue to operate as normal.— Flybe ✈ (@flybe) February 16, 2019
British Airline Pilots' Association general secretary Brian Strutton said: "The collapse of Flybmi is devastating news for all employees.
"Regrettably Balpa had no warning or any information from the company at all."
"Our immediate steps will be to support Flybmi pilots and explore with the directors and administrators whether their jobs can be saved."
Last year the airline ran 29,000 flights, carrying 522,000 passengers.
Flying from Aberdeen, Derry, Bristol, the East Midlands, Stansted and Newcastle in the UK, its planes travelled to destinations in the Czech Republic, Denmark, France, Germany, Italy, Norway, Poland and Sweden.
Travel expert Simon Calder told BBC News it had been an "extremely difficult winter" for many airlines.
"Small airlines which do not have the weight of their bigger rivals are particularly vulnerable," he said. "There are simply too many seats and not enough people."
A spokesman for the Department for Transport described the situation as "very disappointing" and said the government was focused on supporting affected passengers.