Aer Lingus doubled its operating profit to €104 million ($120 million) over the first half of the year, the strongest interim result of the four main IAG carriers.
It generated 8% higher revenues, at €899 million, for the six months to 30 June.
But Spanish budget carrier Vueling suffered an €11 million operating loss, deeper than the €7 million recorded in restated figures for last year.
IAG says that Vueling continued its efforts to reduce network seasonality, with growth in the first half, but air traffic control strikes in France led to a “significant level of cancellations” for the airline.
Vueling’s revenues of just over €1 billion for the half-year were up by 11.5%, IAG has disclosed.
British Airways naturally contributed the largest operating profit, €868 million before exceptional items, a rise of 17%, although its revenues edged upwards only by 1.2% to €7.1 billion.
The UK flag-carrier also benefited from an exceptional gain of €620 million, taking its overall operating profit to €1.49 billion.
This gain was the result of changes to the airline’s employee pension scheme, partly offset by employee severance costs associated with a BA restructuring programme.
Spanish flag-carrier Iberia’s operating profit also increased by 17%, to €102 million, on largely flat revenues.
IAG has not detailed the financial performance of its long-haul budget airline Level, it simply lists “other” companies in the group as contributing a €52 million profit.