With

US Airways

( UAIR) facing a second bankruptcy filing or even liquidation, regional partner

Mesa Airlines

(MESA) - Get Report

is looking at ways to reinvent itself as a low-cost carrier if its partner goes under.

The Street.com

has learned that in a conference call last week with pilots represented by the Air Line Pilots Association, Mesa CEO Jon Ornstein informally approached the head of Mesa's pilot union, Captain Andrew Hughes, with a plan to fly 737 jets independently if US Airways were to cease operations. In short, Mesa is considering a contingency plan to become a low-cost carrier serving US Airways' hubs.

"We've made that proposal to unions. We need to have a contingency plan," said Ornstein, confirming the company's plans but declining to give details. "Time is of the essence here, and if we're doing anything, we have to move quickly and be ready to move quickly."

Indeed, the company's contract to fly regional routes for US Airways accounts for upwards of 45% of Mesa's revenue, according to UBS research. Mesa also flies for United Airlines, a unit of

UAL

(UALAQ)

, and for

America West Airlines

( AWA). But with one of Mesa's best customers warning that it will need additional wage cuts or be forced back into bankruptcy, Ornstein stressed that his company is trying to be ahead of the curve.

"The reason why we're doing this -- it's not because of pending problems with US Airways -- there's just a long lead time to do things," said Ornstein. "You can't just turn on a switch and have airplanes on line to fly and reservation systems in place."

And if US Airways does go under and stop flying, an event that UBS Warburg analyst Robert Ashcroft deemed unlikely in a

research note on May 10, it would create a vacuum in three of its hub markets: Philadelphia, where

Southwest Airlines

(LUV) - Get Report

has already moved in; Pittsburgh, and Charlotte, N.C. Under this scenario, the old US Airways route structure would be "balkanized," with a number of competitors all moving at once to take advantage.

According to a source close to the company, Mesa is currently weighing a number of options for that scenario.

One option would be to find another partner to replace US Airways. Already, rumors are swirling about Mesa pairing up with Richard Branson's

Virgin Airways

, which is laying plans to launch a low-cost carrier in the U.S., with a hub in either San Francisco or New York. Although Ornstein denies having conversations with the still-unannounced Virgin outfit, he was the chairman, president and CEO of Virgin Express in Europe prior to joining Mesa.

"Ornstein has probably talked to Branson about doing some business," said Helane Becker, airline analyst at The Benchmark Co., a New York-based brokerage. "I wouldn't be surprised. He's an entrepreneur more than an airline person, and he will do what he has to do for his airline to be profitable."

If Mesa cannot find a new partner, then the carrier may transform part of its regional business into an independent low-cost operation serving the old hubs that US Airways served, essentially creating a low-cost US Airways. The move bears a passing resemblance to the one that

Atlantic Coast Airlines

( ACAI) is now pursuing from Dulles Airport in Washington, D.C., after, coincidentally enough, Mesa's unsolicited bid to buy ACA failed.

Other options include leasing the regional jets it would have used to fly for US Airways or making an investment in a smaller airline, which it would then use to fly the 737s that are preferred by low-cost carriers.

While the details about Mesa's plans are new, the fact that the carrier is laying plans is not. On its quarterly conference call, Mesa executives said they were considering "contingency plans for several alternative scenarios" if US Airways were to file for Chapter 11 bankruptcy protection again.

"What they're doing is basically trying to figure out if these plans make sense," Becker said. "They feed US Airways flights in Pittsburgh and are concerned how they'll survive if it liquidates. The question is, how do you protect your interests?"

But Ornstein may be doing more than just protecting his interests. With $228.7 million in cash on hand, the profitable carrier has been kicking the tires on a number of possible ventures since its bid for ACA was spurned earlier this year.

In early May, sources told the

Honolulu Star-Bulletin

that the company was one of 13 partners hoping to be a part of Hawaiian Airlines' bankruptcy reorganization plan. And after US Airways announced in late April that Pittsburgh would no longer be a hub, downgrading it to a "focus city," Ornstein told the

Pittsburgh Post-Gazette

his company was considering stepping in to boost service there.

Mesa's behind-the-scenes concerns over a worst-case scenario unfolding at US Airways are driving the contingency planning, but with the industry entering its fourth year of losses, perhaps the carrier is weighing a new endeavor as well.

"First off, if you look at the deals we've done, we're careful. We were looking to do something that makes sense for the company," Ornstein said. "But we're opportunistic, because everyone hates the airline industry now, and this is the time when you can make money."

Calls to the Air Line Pilots Association were not returned by the time this story was published.