Both Airbus and Boeing now offer aircraft that appear capable of flying non-stop commercial flights from Sydney to London - the "Holy Grail" for Australian carrier Qantas Airways Ltd. As long as oil prices don't go much higher than around $70 per barrel, the 20-hour flight can be financially viable, and could be on schedules within five years, aviation experts say.Airbus has increased the range of its A350-900ULR to 9,700 nautical miles (17,960 kms) from the 8,700 nautical miles announced when it sold the plane to Singapore Airlines in 2015 for delivery next year, a spokesman told Reuters. Including headwinds, the Sydney-London flight is equivalent to 9,600 nautical miles."These aircraft, we think, are potentially real goers on these routes," Qantas CEO Alan Joyce told Reuters of the A350-900ULR and the bigger but less advanced Boeing 777-8."You know from what they have done on other aircraft that Sydney-London and Melbourne-London has real possibility." For Qantas, a non-stop Sydney-London route that cuts three hours off the flight time would allow it to charge a premium and differentiate its product from the around two dozen other airlines plying the so-called Kangaroo route with stop-offs in Singapore, Dubai and Hong Kong.