Belfast International Airport is pursuing a legal claim against Aer Lingus over what it claims was a breach of contract by the airline, according to BBC News.
Aer Lingus switched to George Best Belfast City Airport in 2012 after previously operating from International.
The early termination of the 10-year contract was, according to lawyers representing the airport, a breach of contract as it broke what they say was "a binding commitment".
BBC News reports that the grounds for this is based on a series of letters that were exchanged during the negotiation process in 2007.
Aer Lingus denies responsibility. The case will take place at the High Court and is expected to last a number of days.