THE NUMBER of passengers carried by Aer Lingus in May declined by 9.9 per cent year on year, due largely to 11 days of disruption caused by the volcanic ash drifting from Iceland.

Aer Lingus carried 876,000 passengers during the month compared with 972,000 in the same month of 2009.

In the year to date, the airline has carried 3.36 million passengers, down 8.7 per cent on the same period of last year.

Aer Lingus’s short-haul passenger numbers declined by 9.6 per cent to 797,000 while its long-haul services recorded a 12.2 per cent decline in traffic to 79,000.

In spite of the decline in passenger numbers, Aer Lingus’s overall load factor – the number of seats filled on each aircraft – was 79.3 per cent in May, a year-on-year increase of 5.6 points.

This reflected a 17.7 per cent reduction in capacity by the airline over the period.

For the first five months of the year, Aer Lingus’s load factor was 73.9 per cent, up 1.6 points on a year earlier.

Aer Lingus’s short-haul services achieved an 80 per cent load factor in May.

The airline reduced its capacity on short-haul flights by 11.6 per cent during the period.

Its long-haul load was 77.9 per cent, an increase of 11.7 points. Aer Lingus reduced its capacity on flights to the United States by 28.1 per cent over the period.

Last week, Ryanair announced a 17 per cent year-on-year increase in its passenger numbers for May to 6.44 million. Its load factor was static at 81 per cent.

Ryanair’s May figures included up to 250,000 passengers who were “booked to fly on flights which were cancelled due to the unnecessary closures of parts of EU airspace following the volcanic eruptions in Iceland”.

The airline said it had carried 68.3 million passengers in the 12 months to the end of May 2010.