Aer Lingus traffic jumped 2pc year-on-year to 1.148 million passengers in June.
The overall passenger load factor - the extent to which its planes were full - for the month was up 0.3 percentage points to 85.8pc. Transatlantic traffic grew sharply, with passenger numbers up 15.6pc to 163,000 for the month.
Short-haul passenger numbers increased by 1.5pc to 867,000, compared to 854,000 in June 2014.
However, passenger numbers on the airline's regional service fell 9.2pc to 188,000.