Aer Lingus has reported an operating loss of 27.8 million euro in the first six months of the year.
Christoph Mueller, chief executive, blamed the losses on a cabin crew dispute at the start of the year.
He said the airline experienced a strong second quarter, recording a profit of 25.9 million euro.
"This result was underpinned by the continuing positive impact of our capacity management strategy, stabilised passenger numbers, strong yield growth and the absence of airspace closures in northern Europe which occurred in 2010," he said.
"Although economic conditions in Ireland remain challenging, we are pleased with the booking profile for the rest of the year and we are positive about our trading prospects for the remainder of 2011."
Aer Lingus said passenger numbers were up 8.3% to the end of June, with an 8.4% rise in yield per passenger.
Mr Mueller added: "We expect revenue growth in the second half to be broadly similar to that of the first six months.
"As a result, we are more positive about the profitability of the business in 2011 than we were at the start of the year."