Esken Limited (LON:ESKN) said Stobart Air has gone into liquidation after plans to sell the airline fell through.
Potential buyer Ettyl was unable to raise the finance and Esken said it was not prepared to provide any more financial support.
The franchise agreement with Aer Lingus has been terminated with flights cancelled from Belfast to a number of UK regional airports.
Around 480 jobs will be lost through the liquidation.
Esken said its plans going forward will revolve around Southend Airport and also Carlisle, which it will now keep as part of the business.
Talks are in the final stages with a strategic partner to invest money into Southend Airport, which it said would release significant liquidity for the group.
Details are expected with the full-year results later this month and Esken said this funding would allow it to clear its outstanding bank debt.
David Shearer, executive chairman, said: “It is disappointing for all stakeholders that we have been unable to conclude the sale of Stobart Air as a going concern despite the tireless efforts of my executive colleagues, the management team of the Airline and the team of advisors who have supported them.
“I am acutely aware of the impact this will have on the staff, customers and the businesses associated with the Airline but the continuing impact of the pandemic in terms of lockdown and limited travel has prevented us from achieving a better outcome.”
“Our focus now is to secure the position for the rest of the Group and ensure that we have the necessary resources to support the recovery plans for our two core businesses as we anticipate the return to normal activity levels in a post COVID world.
“The discussions on future financing including the strategic partnership for LSA are continuing and I fully expect to bring these to a positive conclusion when we announce our year-end results by the end of June.”