WASHINGTON (Bloomberg) — Billionaire Richard Branson’s bid to start an American airline may help Virgin Atlantic Airways Ltd., the UK carrier he controls, regardless of the decision by US authorities on his proposal.US approval of Virgin America, the planned startup, would give Branson domestic routes in the world’s biggest aviation market. Rejection may let him keep rivals off the US-UK routes where Virgin Atlantic is the second-largest airline.

“If Virgin’s domestic application ends up not being approved, or being delayed another year or two, it’s going to be hard for the US to make a big push on opening the markets in the UK,” said Ed Faberman, former deputy chief counsel for the US Federal Aviation Administration.

A decision on Virgin America’s bid may come this month, said a person familiar with the matter who didn’t want to be named because the timing hasn’t been announced.

Branson’s closely held Virgin Group Ltd. put up 25 percent of the initial $177 million investment to start Burlingame, California-based Virgin America, as well as a $53 million loan. Virgin America officials say US investment firms Black Canyon Capital in Los Angeles and New York-based Cyrus Capital Partners control 75 percent of the carrier.

Virgin America, which plans to start flying between New York and San Francisco, recruited Fred Reid, a former Delta Air Lines Inc. president, to be chief executive and Donald Carty, former chairman and CEO of American Airlines parent AMR Corp., to be chairman.

Continental Airlines Inc., American Airlines and US Airways Group Inc. oppose Virgin America’s bid. The start-up doesn’t meet rules limiting foreigners to 25 percent of US airline voting equity and barring them from having “actual control,” the US rivals said in government filings.

Virgin America filed its plan with the US Transportation Department a year ago this week, and Branson predicted in January the new airline would be flying in six to nine months. Those hopes were dashed when the department put off a decision while it pored over additional information requested from Virgin America, including ownership details.

The carrier, if approved, eventually might try to send passengers to Virgin Atlantic, said Faberman, the former FAA official. That would let Branson share in the revenue going to alliance partner Continental, which funnels travelers from 19 US cities to Virgin Atlantic, said Faberman, a partner with Wiley Rein & Fielding LLP in Washington and head of a trade group for small US carriers.

A Virgin America spokesman, Gareth Edmonson Jones, said it was too soon to speculate on any alliance with London-based Virgin Atlantic. “The purpose of Virgin America is to be a damn good airline in its own right,” he said. Branson declined to be interviewed for this story.

“There is no managerial or operational link between Virgin Atlantic and Virgin America,” said Paul Charles, the UK airline’s director of corporate communication.

Virgin Atlantic said in June that its fiscal-year profit more than doubled after the airline attracted more business travellers. Profit before tax and one-time items rose to $41.6 million ($76 million) in the year ended February 28, from $20.1 million a year earlier. Sales climbed 17 percent to $1.91 billion.

Under a pending US-EU aviation agreement, more US carriers could fly to London’s Heathrow airport. A 1977 US- UK treaty limits US-Heathrow routes to Virgin Atlantic, British Airways Plc, American and UAL Corp.’s United Airlines.

Rejection of Virgin America would let Branson argue that the UK government should oppose the new agreements because the US didn’t open its market to him, said Charles Hunnicutt, who was an assistant transportation secretary under President Bill Clinton. A “no” vote from any EU nation would sink the accord.

Killing the aviation agreement would block more competition on the US-UK routes, where Virgin Atlantic trails only British Airways in passenger traffic.

Heathrow accounted for two-thirds of US-UK traffic in 2004, Dresdner Kleinwort Wasserstein Securities LLC said in a report in April.

Heathrow fares average $523 to and from the US, compared with $446 to and from London’s Gatwick airport.