Budget airline Ryanair saw passenger growth outstrip rival easyJet last month as the two firms gave an update on their travel performance.
The number of people flying with easyJet jumped 9.5% to 7.5 million in May compared to 2016, while Ryanair saw passenger levels rise 11% to 11.8 million over the period.
Focussing on the load factor - a measure which judges how efficiently airlines are filling seats - easyJet was flat at 95% and Ryanair rose by 1% to 95%.
The update comes after travel and leisure stocks came under pressure on the London Stock Exchange on Monday as investors responded to the London Bridge terror attack, which left seven people dead and dozens more injured.
The travel and hotel industry has seen demand for holidays to Turkey and Egypt suffer over the past year as holidaymakers remain cautious about the destinations following the bombing of a plane from the Egyptian resort of Sharm el-Sheikh and a violent attempted coup by the Turkish army.
There are also concerns that Britain's tourism industry could take a hit following a number of terror attacks in the UK, including last month's Manchester bombing which killed 22 people.
Budget airline easyJet announced large half-year losses in May after being stung by the collapse in the value of the Brexit-hit pound and the later timing of Easter.
The low-cost carrier reported a £236 million pre-tax loss in the six months to March 31, which compares with an £18 million loss in the same period last year.
Meanwhile, Ryanair pledged last month to continue cutting fares as it posted a 6% rise in annual profits despite intense competition and the Brexit vote.
Ryanair chief executive Michael O'Leary said the Irish airline faced ''difficult'' trading as the group posted profits of 1.31 billion euro (£1.14 billion) for the year to March 31.