The attacks on Brussels in March continue to dampen demand for flying in Europe, though traffic was strong during the Easter holidays, Ryanair's chief executive said today.
Michael O'Leary last month had predicted that the airline's profits would fall by €10-20m in the three months from January to March as a result of the Brussels attacks and air traffic control strikes.
He also forecast that airlines would have to cut fares.
Aer Lingus and British Airways-owner IAG and Lufthansa in recent days cited the Brussels attacks as a factor in trimming growth plans for the year.
"The Brussels effect has dampened demand into April-May though funnily enough it did not create as much disruption over the Easter period, but I think that's because a lot of families had holidays booked," O'Leary said.
He made his comments at a conference in Dublin today.
He said Brussels Zaventem airport, where suicide bombs killed 16 people, would be back up to full capacity by the end of June and the impact on summer demand would depend on whether there were further attacks.
"The danger for us is that you have one or two more of these events somewhere in Europe during the summer and that will effect confidence," he said.
Asked if he was concerned about summer demand, O'Leary said he was "always worried about consumer confidence ... business is going great and when business is going great, that's when you worry."
Ryanair is due to announce its results for the year to the end of March on May 23.
Earlier the airline reported another increase in passenger numbers for April as it continues the roll-out of its "Always Getting Better" customer programme.
Ryanair said it carried a total of 9.9 million passengers last month, up 10% on the 9 million in April 2015.
Its load factor - or how many seats it fills on each flight - also rose by 2% to 93%.
Ryanair said the the increased numbers were achieved despite more air traffic control strikes in Belgium, France, Greece and Italy during the month.
