I believe Qantas doesn't has a specific policy on this as some airlines do, but they are supposed to (according to Qantas) move the obese passenger or the affected one if seats are available. And also I believe Australian airlines can't require an obese passenger to pay for an additional seat (something about obesity being a disability), so it's up to the passenger themselves whether they want to buy another seat.
Last edited by DragonSoul; Dec 14, 2017 at 10:38 pm