Aer Lingus carried more than 1.26 million passengers in July – a 4.3% improvement on the same month of 2014.
Most of the growth came from the airline’s short haul routes, which had 962,000 passengers in the month – a 34,000 (3.7%) gain year-on-year.
However Aer Lingus’ long haul services saw the biggest proportional gain with 168,000 passengers, a 26,000 (18.3%) increase on July 2014.
The number of passengers being carried on the Aer Lingus Regional service was down, however, falling by 8,000 (5.6%) to 134,000.
Aer Lingus Regional is operated under licence by Stobart Air and flies smaller aircraft to regional airports, including a number in Britain and France.
Overall the airline said its load factor – the percentage of seats filled on each flight – had improved to 88.6%, though its long haul service was down slightly.
The July figures bring to 6.45m the number of passengers who have travelled with Aer Lingus and Aer Lingus Regional so far this year – a marginal improvement on the same seven months of 2014.
Aer Lingus is currently in the process of being acquired by British Airways owner International Consolidated Airlines Group, with the deal expected to close in the coming weeks.