UK air travel increased during winter, airport operator BAA said.
UK airport operator BAA has said that the closure of Heathrow and Stansted earlier this month by the volcanic ash cloud has cost it £28m.
Its comments came as it reported a £195.5m pre-tax loss for the three months to March, an improvement on the £316.2m loss seen a year earlier.
But it said the harsh weather, tighter security, strikes and the recession had failed to curb air travel over winter.
Passenger traffic rose 0.2% to 18.6 million during the quarter.
However, it warned that the months ahead could be tough.
"The rest of 2010 continues to present significant financial challenges for the industry as a whole," said BAA chief executive Colin Matthews.
"We currently estimate that the closure of Heathrow and Stansted due to volcanic ash will have a total impact on 2010 adjusted EBITDA (adjusted earnings before interest, tax, depreciation and amortisation) of £28m."
BAA, which is majority owned by Spain's Ferrovial, operates six airports in the UK - Heathrow, Stansted, Glasgow, Edinburgh, Aberdeen and Southampton. The company sold Gatwick airport for £1.5bn last year.