Qantas customers' personal data has been compromised after a data breach revealed the names, seat numbers and frequent flyer numbers of eight passengers to another passenger looking at the Qantas check-in app on Thursday. The app, which was used to check in for a flight between Newman, Western Australia, and Perth, showed the length of the flight and that a snack or brunch would be available, but the Qantas passenger was shocked to be able to see details for other passengers.