This is a reasonable estimate from the data we have, but it refers to all flights, not just international ones. It comes from analysis of government survey data from 2014 by campaigners for a frequent flyer levy.
In March 2014 the survey asked a random selection of 1,000 adults in Great Britain how many trips by plane they’d taken in the last 12 months. 52% hadn’t flown at all. 15% of people had flown three or more times and have been called ‘frequent flyers’.
One of the researchers shared their analysis with us. A more detailed breakdown of responses shows that those 15% of flyers made 70% of the total flights.
We asked the Department for Transport, which designed the survey, about this claim. It said a more precise estimate is that the 15% of adults in Great Britain who made 3 or more flights (our frequent fliers) made 71% of flights from March 2013 to March 2014.
The same survey asked about what types of flights people had taken. 7% had flown domestically, 37% short-haul within Europe, and 18% long-distance. People could choose more than one option, so we can’t separate domestic flyers from international ones.
A bigger survey, The National Travel Survey, asks 18,000 people in England how many times they flew abroad in the last year. In 2015, it found 12% of people had flown three or more times. The figures are less detailed, so we can’t calculate the percentage of flights those people accounted for in the same way.