The FTSE 100-listed firm – which also owns Spanish airlines Iberia and Vueling plus Ireland’s Aer Lingus – saw reported passengers carried increased by 5.7% year-on-year to 9.2mln in March, up from 8.7mln in the same month a year ago.
In the year to date, IAG said reported passenger numbers were up 6.2% to 24.4mln from 23.0mln at the same stage in 2018.
That was helped by robust growth from its core domestic unit - including UK, Spain, Ireland and Italy – which saw passenger growth of 7.4%, and in other European markets which carried 5.0% more passengers.
The company’s traffic, as measured in revenue passenger kilometres (RPKs) rose by 5.1% to 22.3mln, up from 21.2mln a year earlier, with the figure in the year-to-date up 6.4%.
British Airways traffic rose 1.6% year-on-year in March to 12.6mln, while Aer Lingus and Iberia saw traffic up 9.8% and 9.5% respectively, and Vueling's traffic was up 2.5%.
The company’s load factor - the number of passengers as a proportion of seats available - increased marginally to 83.7% in March, compared to 83.1% a year earlier, and to 80.7% in the year-to-date from 80.5%.