Australian airline Qantas is exploring new nonstop flights that would be the world’s longest — but 19-plus hours on a plane can be taxing for those on board.

Australian airline Qantas is exploring new nonstop flights that would be the world's longest — but 19-plus hours on a plane can be taxing for those on board.

Australian airline Qantas is exploring new nonstop flights that would be the world’s longest — but 19-plus hours on a plane can be taxing for those on board.

Australian airline Qantas is exploring new nonstop flights that would be the world’s longest — but 19-plus hours on a plane can be taxing for those on board.