Ultra long-haul airline flights have always demanded a balancing act between fuel costs and extra weight, and the efficiencies gained from high-altitude cruising and fewer takeoffs and landings. But a new generation of fuel-efficient jetliners, led by Boeing's 787-9 Dreamliner, 777-8x and Airbus's A350-900ULR, is changing the equation. Qantas has just announced that in March it will launch the first non-stop passenger service between Britain and Australia, with a 14,498-kilometre 17-hour London-Perth route