Video report by ITV News Correspondent Ivor Bennett
All flybmi flights have been cancelled with immediate effect after the airline announced it was filing for administration.
The East Midlands-based airline blamed Brexit "uncertainty" as well as spikes in fuel and carbon costs.
It is understood there are 1,500 passengers who were scheduled to fly with the airline on Sunday, most of whom are thought to be business passengers.
The firm employs 376 staff and operates 17 planes flying to 25 European cities.
Affected customers have been advised to contact their insurance providers, credit card companies or travel agents.
A spokesperson for flybmi said: “It is with a heavy heart that we have made this unavoidable announcement today.
"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.
"These issues have undermined efforts to move the airline into profit.
"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 and lack of confidence around bmi’s ability to continue flying between destinations in Europe.
One passenger, on route to Austria, said he had already gone through security at Bristol airport when his flight was cancelled.
Richard Edwards told ITV News staff at the departure gate had told him the flight had been cancelled due to "operational reasons".
Mr Edwards was given alternative flight arrangements with flybmi's partner airline Lufthansa but said he is worried about how he'll make it back to the UK.
Speaking from Munich he told ITV News: We're obviously happy that we're in Munich and we're off going on to Austria, skiing.
"But obviously it's a bit of a worry as to how we get back."
He tweeted: "Our @flybmi from Bristol to Munich (which had previously been changed from Southampton) was cancelled with no explanation after we had gone through security!"
He later added that he had arrived in Munich, having flown with Lufthansa from Heathrow.
Customers due to fly out tomorrow should make alternative travel arrangements as Flybmi will not reschedule or rebook flights.
People who booked directly with the airline should contact their credit or debit card company to claim a refund.
Those who have booked with Flybmi's partner airlines can contact them to find out what the options are.
Flybmi's partner airlines include Lufthansa, Brussels Airlines, Turkish Airlines, Loganair, Air France and Air Dolomiti.
A Department for Transport spokesman said: "It is very disappointing that flybmi has gone into administration and we know this will be a very difficult time for those who have lost their jobs as a result.
"This will also of course be disruptive for passengers. We are fully focused on supporting those affected and are in contact with airports, airlines and other transport providers to ensure everything possible is being done to help them."
Aviation experts have said Brexit is "definitely a contributor" towards flybmi's collapse.
Alex Macheras, an aviation analyst, told ITV News: "Ultimately this is an airline that not only operates from the UK but it also operates EU to EU."
He added: "With that they need the security that after Brexit, those routes will be able to continue.
"Now because of the lack of clarity surrounding Brexit, they have blamed this, which is expected given that it is bound to add some stress into the complexities of what the airline is facing."
British Airline Pilots' Association (Balpa) general secretary Brian Strutton said: "The collapse of Ffybmi 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."