The 20-hour flight is coming. And it may have a gym and bunks.

The goal of a non-stop flight from Sydney to London -- half the way around the planet -- took a leap forward as the world's top planemakers convinced Qantas Airways they can make the 20-hour route a reality.

A year after Qantas Chief Executive Officer Alan Joyce publicly challenged Boeing and Airbus to design a plane capable of making a viable direct…