Aer Lingus is set to cease direct flights between Shannon and Heathrow and transfer the link to Aldergrove airport in Northern Ireland.
The official announcement will be made by the Aer Lingus chief executive Dermot Mannion after he meets Aer Lingus personnel in Shannon on Tuesday morning and then attends a news conference at Stormont on Tuesday afternoon.
It is not clear if the Shannon decision will involve job losses, as negotiations between the unions and the airline are likely.
The Aer Lingus move to Aldergrove will create at least 100 jobs and as well as the Belfast to Heathrow direct flights.
Aer Lingus is expected to introduce at least six services from Aldergrove to mainland Europe.
Earlier this year Aer Lingus confirmed it would retain scheduled services from Shannon to the US throughout the winter months.