A “virtual airline” which ran flights between Belfast City Airport and the Isle of Man has gone into liquidation.
Citywing said the decision was taken after an airline which operates flights on its behalf had its permission to fly suspended.
Van Air Europe faced the action after an incident last month at Ronaldsway Airport in the Isle of Man.
Citywing told passengers not to turn up at the airports and said advice would be given on refunds in “due course”.
All its flights from Saturday 11 March have been cancelled.
‘Put the brakes on’
Groups who could be affected are motorbike racers, their families and fans trying to get to and from the Isle of Man.
Motorcycle road racer Conor Cummins told Manx Radio, he hoped there would be a solution soon.
“The TT is coming up when there’s a massive influx of fans coming from Ireland,” he said. “It could put the brakes on a lot of things”.
Mr Cummins and his fiance are also affected personally, as they are due to get married in Northern Ireland in November with many family members and friends set to travel over with them.
The UK Civil Aviation Authority (CAA), which did not regulate the Isle of Man-based ticket seller, advised passengers with forward bookings to contact their card or insurance provider for refunds.
The firm sold flights on scheduled services between the Isle of Man and various UK destinations.
It also operated a route between Cardiff Airport and Anglesey under a public service contract with the Welsh Assembly Government.
Citywing said it had suffered “considerable losses” and had found it difficult to source alternative aircraft after Czech-registered Van Air lost its licence.
Its licence was suspended by the regulator after one of its flights from the Isle of Man, bound for George Best Belfast City Airport, was forced to turn back because of high winds.
The flight, on 23 February, coincided with Storm Doris.
Another airline was drafted in to run Van Air’s routes until an investigation was completed.
However, Citywing released a statement on Friday saying: “The company has tried to offer a service while suffering considerable losses but these have proved unfortunately to be commercially unsustainable.
“It is therefore with much sadness and deep regret that the directors of Citywing Aviation Services Limited have had to take the difficult decision to close the company today and put the company into liquidation.”