Airline Flybe is set to collapse within hours, putting 2,000 jobs at risk it has been reported.
The regional carrier narrowly avoided going into administration in January, but has continued to lose money.
A drop in demand caused by the coronavirus “made a difficult situation worse” for Flybe.
Flybe, which serves many parts of the UK from the Channel Islands to Aberdeen, had been hoping for a £100million injection and changes to Air Passenger Duty taxes.
The carrier faced a number of challenges last year and was bought by a consortium which includes Virgin Atlantic.
Crisis talks took place throughout Wednesday to try and secure a rescue package, but no deal was agreed.
Flybe’s website has stopped working, with visitors being shown a message stating “This link is no longer live.”
Exeter-based Flybe said the impact of the coronavirus outbreak on demand for air travel was partly to blame.
Passengers who had boarded a flight in Glasgow on Wednesday evening had to disembark after "a fuel issue" meant the flight was cancelled.
Passengers booked on flights for Thursday are awaiting confirmation that they won't be able to fly.
In January, Flybe agreed an arrangement to defer tax payments of “less than £10 million” with HM Revenue and Customs, while ministers pledged to review Air Passenger Duty.
Mike Clancy, general secretary of the Prospect union, said it would be a “devastating blow” for its members working for Flybe if it goes into administration.
He said: “Prospect will do everything we can to support our members but the truth is the Government has badly let them down.
“The failure to provide the loan that is required as part of a package of rescue measures means the Government has failed in its commitment to every part of the UK.”
The Exeter-based airline’s final airborne flights are expected to land at airports in the UK late on Wednesday evening.
For the past 15 years Flybe had been trying to compete with some of the bigger aviation companies but failed to make the mark.
10 years ago, the failed airline made every effort to be taken seriously when it raised money with a stock market float, and set out a plan to become Europe's biggest regional airline, flying mid-sized planes between secondary cities. However, it did not work like it does in America where regional airlines, often flying as franchises of the larger network carriers are successful.
Nadine Houghton, national officer of the GMB union, said: "These unfolding developments are a tragedy not only for Flybe's loyal workforce, but a domino effect now puts 1,400 jobs in the wider supply chain at immediate risk and threatens the future of vital regional airports.
"The last thing regions crying out for investment need is to see infrastructure that maintains good jobs ripped away."
Shadow transport secretary Andy McDonald said: "The collapse of Flybe is disastrous news for passengers and employees alike and will cause real anxiety in many regions throughout the country.
"The Civil Aviation Authority is sadly very well practised, following the collapse of Monarch and Thomas Cook, at responding to airline failure and looking after passengers. No doubt they will do that once more."
Meanwhile,Ryanair has launched "rescue" fares for March and April on five routes following Flybe's collapse. They include flights between Bournemouth and Dublin, Belfast and Stansted and Belfast and Manchester.
Train operators across Britain are also providing free travel to customers and Flybe staff who are unable to travel over the next week.