Another U.S. airline flies into the sunset

In a few days, a once-thriving part of the nation's aviation industry will pass into history. U.S. Airways is about to be absorbed by American Airlines (AAL), just the latest in a series of mergers and consolidations in the aviation sector.

U.S. Airways flight 1939, flying from San Francisco, will land in Philadelphia at 6:18 a.m. Eastern time on Saturday. And with its touchdown, the 76-year-old airline, which began in 1939 as an air-mail service called All-American Airways -- will come to an end.

On the practical side, the change means the U.S. Airways website and mobile app for ticket purchases and check-ins will no longer work as of Saturday. Customers will be directed to American's website and app.

Still left hanging is what might happen to U.S. Airways hubs in Phoenix, Charlotte and Philadelphia as the integration process progresses.

No matter which hubs survive or disappear, airline passenger advocates are marking U.S. Airways' passing as another setback for air travelers.

"Consumers will lose because they won't have as much choice," Charlie Leocha, chairman and co-founder of Travelers United, told CBS MoneyWatch. "Prices are going to be going up, capacity (the number of available seats) will be held as low as possible, so that demand is kept high, and we're not in a very good position anymore."

In recent years, with the 2008 merger of Northwest Airlines with Delta (DAL), followed two years later by the Continental-United Airlines merger (UAL) and now the US Airways-American merger, four airlines (including Southwest) now control at least 80 percent of U.S. domestic air travel.

And with the creation of these megacarriers have come allegations of price fixing by the airlines. The U.S. Justice Department began an investigation in July into possible collusion by the major carriers to artificially keep fares high.

And last month, the Justice Department's antitrust division asked American, United Continental, Delta and Southwest (LUV) for details "about meetings with their major shareholders in which 'industry capacity' was discussed."

Air travel is a big part of the U.S. economy, and it has rebounded from its post-9/11 lows. In 2012, according to the FAA, overall aviation made up 5.4 percent of the U.S. GDP, added $1.5 trillion in total economic activity and supported nearly 12 million jobs.

But given how much the airline industry has consolidated in recent years, some analysts believe the three major air carriers will find themselves under much greater scrutiny.

"We've been talking about going to three megacarriers for the last 20 years," Andrew Goetz, professor and faculty member at the University of Denver's Intermodal Transportation Institute and the Urban Studies Program, told CBS MoneyWatch.

"A lot of people felt that that was going to happen, especially because airlines like U.S. Airways were really struggling and a having a lot of difficulties staying profitable," he said. "There was this feeling, a sense of inevitability. ... But now that we've reached this new equilibrium, I think anything that goes beyond this is going to be looked at a lot more carefully."

In the meantime, said Goetz, Americans should take a moment to remember U.S. Airways and other historic airlines like Eastern and Pan American. These companies left behind powerful and important legacies for the nation's air travelers.

"So, it's definitely worth pausing and reflecting on what's happening and why it's happening," he said, "and what this means for the future of the airline industry."