Aer Lingus says its passenger numbers for February were up 7.3% on the same month last year to 616,000.
But the load factor - the percentage of seats filled - slipped back slightly to 71.9% from 72%.
For the first two months of the year, passenger numbers are up 4.8% on the same period last year to 1.2 million, but the load factor of 68.9% compared with 70.9% a year ago. Capacity has increased by more than 6% in that period.
Long-haul passenger numbers are down 5.6% in the first two months of the year, while short-haul numbers are up 6.3%. But the load factor for short-haul routes is lower at 67%, down two points on the first two months of 2006.
Separate figures from the Dublin Airport Authority showed that February passenger numbers in Dublin grew by 14% on the same month last year to 1.5 million.
Continental European routes showed the fastest pace of growth at 34%, but UK and North American traffic both recorded drops of 2%.
