Thousands of passengers have had travel plans disrupted after airline Flybmi suspended all flights, and said it was filing for administration.
British Midland Regional Limited, which operated as Flybmi, announced on Saturday evening that it was filing for administration.
It is understood 1,500 passengers had been scheduled to fly with the airline today.
Customers of the airline have been told not to come to the airport unless they have re-booked flights with alternative providers.
Flybmi said it cannot purchase, rearrange or reschedule any flights on behalf of customers.
The East Midlands-based airline operated flights on routes to 25 European cities, including Aberdeen, Bristol, City of Derry, East Midlands, London Stansted and Newcastle.
From Newcastle, it operated regular flights to Brussels in Belgium and Stavanger in Norway.
Newcastle International Airport said in a statement: "We are aware that the airline flybmi has filed for administration.
"The airline operated the Newcastle to Brussels and Newcastle to Stavanger routes.
"Passengers due to travel with flybmi should refer to the information that has been provided on the airline’s website www.flybmi.com."
The airline said difficulties which led to the collapse had included increases in fuel and carbon costs, and challenges "particularly those created by Brexit".
An extensive Q&A on the airline's website - the only page now accessible to customers - lays out various options for those affected.
* Customers have been advised to contact their payment card issuer to get a refund for flights.
* Those who have booked through a travel agent or partner airlines are advised to contact their agent or airline.
* The Civil Aviation Authority (CAA) said travellers should contact their insurance provider as their policy may include cover for scheduled airline failure.
* It advised passengers whose flights were part of a package holiday to contact the travel firm they booked with.
If the firm holds an ATOL (Air Travel Organiser's Licence), it is responsible for flight arrangements and must either make alternative flights available so the trip can continue or provide a full refund, the CAA said.
A spokesman for the Association of British Insurers (ABI) said: "Where alternative travel plans are made, any existing travel insurance policy can usually be transferred to cover the new arrangements."
However, the ABI said standard travel insurance policies may not cover the failure of the air carrier and said passengers should check their policy.
Flybmi flights operated out of Aberdeen, Bristol, East Midlands, London Stansted, Newcastle and City of Derry and a number of European airports.
The airline said it carried 522,000 passengers on 29,000 flights last year.
Rory Boland, travel editor for the consumer body Which?, said: "This is terrible news for Flybmi passengers, who will be seeking urgent advice on what steps to take.
"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.
"As all future flights have been cancelled, Flybmi customers should explore their options for refunds.
"If you purchased your flight as part of a package you should be ATOL-protected, which means you should get a refund.
"However, if you didn't book as part of a package you may be able to claim the cost back through your travel insurance or credit card issuer, but it depends on your circumstances."