AUSTRALIA and the US have signed an open skies agreement that opens up one of the world’s most lucrative long-haul routes.The deal will allow Australian and US airlines to increase routes, destinations and frequency of flights between the two countries and to other nations.Qantas and United Airlines are currently the only airlines flying non-stop between Australia and the US. Virgin Blue is now likely to push ahead with its plans to begin flights to the US by the end of this year. The carrier wants to fly to the US West Coast using Boeing 777-300ER aircraft.