Airline Aer Lingus lost up to €44million (£32.2m) while operating out of Belfast International Airport (BIA), its boss has told the High Court.
Stephen Kavanagh also insisted it only ever entered into a pricing arrangement for flying out of the airport - not a binding contract.
BIA is suing Aer Lingus for £20m in damages over the airline's switch to Belfast City Airport in 2012. The case centres on a dispute over the terms of a deal said to have been reached in June 2007.
Asked whether Aer Lingus suffered financially from its time at BIA, Mr Kavanagh said it had "lost a significant amount of money in its operation at Belfast Aldergrove".
"In terms of our profit, the negative was €44m," he added. "In terms of costs which directly applied to the operation of the base, it was €21m (£15.3m)."
The difference between the two figures was partly based on corporate overheads, he explained.
Asked about claims Aer Lingus was under an obligation to stay at the airport for 10 years, he said the airline "saw a pricing proposal, based on an initial three aircraft base... and that is the basis upon which we operated".
The case continues.