The volcanic ash crisis cost airport operator BAA £28 million, it said today.
The company, which owns both Stansted and Heathrow airport, announced the losses as it reported a £195.5 million pre-tax loss for the first quarter of 2010.
The result was an improvement on Q1 last year when BAA lost £326.2 million.
BAA blamed the continued financial strain on the winter freeze in January, tighter security and the British Airways strike.
Passenger traffic increased 0.2% to 18.6 million from January to March.
But the company, owned by Spaniards Ferrovial, predicted a tough ride during the rest of the year.
Chief executive Colin Matthews said: "The rest of 2010 continues to present significant financial challenges for the industry as a whole.
"We estimate 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."