Aer Lingus passenger traffic rose by 4.2 per cent to 852,000 in April compared with the same period last year after the airline added aircraft and routes.
The load factor, or proportion of seats filled, fell to 70.5 per cent from 81.2 per cent a year earlier, led by a 17.7 percentage-point drop on long-haul flights Aer Lingus said.
According to the airline this reflects an increase in capacity provided by the introduction of two new long haul aircraft. Yesterday Aer Lingus increased its fuel surcharge on transatlantic flights by up to 30 per cent to offset high oil prices.
Aer Lingus passengers flying between Ireland and New York, Boston, Chiacgo or Washington will now have to pay €65 each way, compared with €50 previously.
Those flying between Dublin or Shannon and Orlando will see their surcharge rise €15 to €75. The fuel charge on flights to and from San Francisco and Los Angeles will rise by €15 to €90. The price increases will take effect on all bookings made from May 14th.
Aer Lingus raised its fuel surcharge as recently as March 19th but the unrelenting rise in oil prices has prompted it to act again just weeks later.
When asked for updated figures on the overall cost of its fuel bill for 2008 and the proportion of overall costs accounted for by fuel, a spokeswoman said an interim management statement would be issued "shortly".
In March Aer Lingus estimated that it would spend €185 million on fuel this year and said that the proportion of overall costs accounted for by fuel would be be 21 per cent.