The effects of a (hypothetical) US Airways merger

If US Airways were swallowed up by another airline, what would it mean for Philadelphia-area travelers?

As the region's dominant airline, with 447 daily departures to 119 nonstop destinations from 85 gates, what would the fallout be to Philadelphia International Airport and the flying public?

This is not to suggest US Airways is going away; there is no indication of that right now.

Chief executive Doug Parker told analysts on last week's quarterly earnings call that Philadelphia's "hub" airline is here to stay and the US Airways' cash as a percentage of revenues as of June 30 was second only to Continental Airlines among the Big Five legacy carriers.

But in this economy, several analysts have suggested one or two big airlines might have to merge in order to survive, should the slump in business travel and rising oil prices continue into next year.

Parker happens to be a big proponent of industry consolidation and twice has tried to combine US Airways - with Delta Air Lines in 2006 and United Airlines last year. (Neither airline was interested.)

If US Airways were to hook up - and some suggest United is a likely partner - what would the scenario be here?

What would it mean for the number of flights, the number of destination cities, domestic and international, and the overall ease of use?

The top question: Would Philadelphia remain a hub and international gateway, or would a new merged carrier retain only United's hub in Washington?

US Airways' other East Coast hub is Charlotte, N.C.

The good news is Philadelphia has fairly strong "origin and destination" traffic, with 60 to 65 percent of passengers beginning and ending their journeys here, as opposed to transfer traffic that passes through.

"If something happens to our hub carrier here, there still will exist a demand that other airlines would backfill, whether it be the legacy carriers or some of our low-fare carriers like Southwest and AirTran," said acting Philadelphia Aviation Director Mark E. Gale.

Airport officials scrutinized "what if" scenarios after US Airways twice filed for bankruptcy protection, in 2002 and 2004, when it later merged with America West Airlines.

"We are in a much different position than say Pittsburgh, when US Airways went through bankruptcies" and closed the Pittsburgh hub, Gale said. Pittsburgh has 20 percent origin-and-destination passengers and 80 percent transfer traffic, which could connect anywhere.

"If an airline like US Airways were to fully shut down, it would take a little time for carriers to step in and fill some of those shoes, but we believe that would occur," Gale said. "And it would occur much quicker on the domestic than the international side.

"Trying to replace the international service would take much longer. This is all hypothetical," Gale said.

After US Airways' second bankruptcy, Philadelphia's airport negotiated new use-and-lease agreements with the airlines. Under the terms, airlines are "primary users" of passenger holding areas and gates, but do not have exclusive or sole rights to areas of the airport.

In addition, Philadelphia's airport purchased all the jet bridges - walkways that connect from terminals to aircraft - that were previously owned by the airlines.

The idea is that should an airline file for bankruptcy "the assets are readily available for us to use for another aircraft" and are not tied up in bankruptcy court, Gale said.

If Philadelphia International were to lose its status as an airline hub - with hundreds of daily flights that feed into international routes and other U.S. cities - it would be a blow.

"Philadelphia would become mostly a transfer airport and people would have to fly elsewhere to get flights to Europe," said airline analyst Roger King, of CreditSights.

"You'd still be able to fly everywhere in the country just like now, but maybe to fewer minor cities. If there are fewer connecting passengers, there might be less demand for some smaller markets."

Passengers would encounter fewer airplane seats, smaller aircraft, and some lost service to destinations.

Robert Mann, an aviation consultant based in Port Washington, N.Y., said history has shown additional airlines pop into a market when an incumbent carrier leaves.

"Airlines won't walk away from a pool of revenue," he said. "If a major hub operator moves out of a market, like US Airways did in Pittsburgh, other airlines say, 'With these guys gone, I can actually participate in that market.' "

Mann does not predict any airline bankruptcies or mergers.

"Airlines are very resilient, very creative. Their self-preservation instincts are extremely strong," Mann said. "As Mark Twain said, their 'death is greatly exaggerated.' "

Although US Airways' Parker might like to pull off a merger, "I can't see it," Mann said. "He has to find partners to finance it. A year from now I think all the airlines will still be around."