Budget airline Norwegian Air has said it will end flights between Ireland and the US next month, blaming the grounding of the Boeing 737 Max.
"We have concluded these routes are no longer commercially viable," it said.
Norwegian, which has struggled to make a profit, said last month the grounding of the Boeing 737 Max plane could undo its plan to return to profitability.
Norwegian said all six routes from Dublin, Cork and Shannon to the US and Canada would end on 15 September.
Boeing's 737 Max fleet was grounded after two fatal crashes, the first a Lion Air flight which crashed into the sea off Jakarta last year, and the second an Ethiopian Airlines' flight which crashed shortly after take off from Addis Ababa in March.
In total 346 people were killed.
"Since March, we have tirelessly sought to minimise the impact on our customers by hiring replacement aircraft to operate services between Ireland and North America. However, as the return to service date for the 737 Max remains uncertain, this solution is unsustainable," said Matthew Wood, senior vice president of Norwegian's long-haul division.
The airline said any customers who already had flights booked would be rerouted onto other Norwegian services.
If passengers no longer wanted to travel with the airline, Norwegian said they would be offered a full refund.
"We will continue to offer scheduled services from Dublin to Oslo, Stockholm and Copenhagen as normal," said Mr Wood.
The airline said any redundancies resulting from the decision to end the Ireland-US routes would be "a last resort".
"Our 80 Dublin-based administrative staff at Norwegian Air International and Norwegian Group's asset company, Arctic Aviation Assets, will not be affected by the route closures," Mr Wood added.
Norwegian Air was founded in 1993 as a small domestic airline, but changed strategy in 2002 to become a budget carrier.
Its low fares have helped it grow rapidly, and it is now Europe's third biggest low-cost carrier.
Last year it launched 35 new routes, carried more than 37 million passengers and added 2,000 staff.
Its big innovation has been to operate low-cost long-haul flights between the UK and the US, which it started in 2014. It now flies to 12 US destinations from London's Gatwick airport.
It has become the biggest international carrier to serve the New York City area, carrying more passengers there than British Airways, Air Canada or Lufthansa, according to figures from the Port Authority of New York & New Jersey.
However, that growth has come at the expense of profits.
The airline lost 1.45bn kroner (£135m) last year, which it blamed on fuel costs, tough competition and issues with engines on its Dreamliner aircraft.
In March, to shore up its finances, Norwegian raised 1.3bn kroner through a share sale and also sold some aircraft.