When US Airways and American Airlines merged to create the world's largest airline, CEO Doug Parker said all nine hubs would be important to the new American.

Four years later, that's still true. Philadelphia continues to be American's European "gateway" with 425 daily departures, and a total of 850 takeoffs and landings each day. Philadelphia is the fourth-largest hub in the network of American, the world's biggest carrier measured by passenger traffic.

But the airline has reduced seat capacity at PHL as it reacts to competition and changing priorities - part of routine adjustments, said American, and in no way a reflection on its commitment to Philadelphia, where it employs 8,500 people.

At American - locked in competition with Delta and other carriers in Los Angeles and New York and with United in Chicago - some hubs have grown a little, and some have shrunk a little in total airline seats, or capacity.

Philadelphia, Phoenix, and Miami have shrunk modestly in American seats in the current third quarter compared with the same period a year ago. Dallas Fort Worth is down fractionally.

Other hubs have added some seats, and Los Angeles has grown the most, as the new American has made LAX its hub for flights to Asia.

Overall, American grew only 0.8 percent, less than 1 percent, in the quarter, said Seth Kaplan, managing partner at Airline Weekly, who analyzed flight schedule data compiled by aviation research firm Diio Mi.

"This starts at a very high level with how much is the airline going to grow or going to shrink. If the airline is going to grow 1 percent this quarter, then where do the planes go?" Kaplan said. "Latin America demand is down, 'OK, cut Miami.' In New York and L.A., you've got a war against Delta. Chicago is going to grow a little because there's head-to-head competition there against United.

"The seats have to come from somewhere, and the answer is a place like Philly, where American can reduce capacity somewhat and still be, by far, the dominant airline," he said. "Very few people are going to stop flying American in Philly because American shrinks there."

Philadelphia International Airport has 7.4 percent fewer American seats in the current quarter compared with a year ago, according to the analysis of flight schedule data. Seats are down 7.8 percent in Phoenix, 2.8 percent in Miami, and 0.1 percent in Dallas Fort Worth.

Chuck Schubert, vice president of American's network and schedule planning, said that while "the numbers can induce headlines," Philadelphia is "no less important today than it was yesterday or even pre-merger. Philly is, and will remain, a very important piece of the American Airlines network."

In combining US Airways' four hubs and American's five into a nine-hub system "you are going to see ebb and flow as we bring those two networks together," Schubert said. "Philadelphia is our transatlantic gateway, and has served that role for many years, and I expect it will serve that role for many years to come."

Philadelphia is a "very important" connecting point for traffic coming out of the Northeast and central Mid-Atlantic into American's route network, he said. The No. 1 contributor to the seat capacity drop here was cancellation of American's daily Tel Aviv flight in January. American announced last year that the economics of the route did not work. The Airbus 332 carried about 250 passengers every day year-around, so losing the route amounted to a lot of seats, Schubert said.

The second-largest seat loss has been Philadelphia-LaGuardia flights. US Airways brought New York area travelers through PHL and onto its network. On American, those travelers fly nonstop from New York.

A third contributor to the drop in seat count was discontinuing a morning flight to London Heathrow that American began in March 2015, flew for about a year, and dropped because it was not popular with travelers who preferred an evening departure, arriving the next morning.

American no longer flies nonstop to Sacramento, Calif., and San Antonio, Texas. It has trimmed flight frequencies - the number of times a day it flies a route - to a few cities, including Washington and Boston. American still has 12 weekday nonstops to Boston and three nonstops to Washington Reagan.

JetBlue also has five weekday flights to Boston.

"There are certainly markets where frequencies have come down, but there are also markets where we have added flying, whether it's through frequency or the use of bigger aircraft," Schubert said. For example, seats to Kansas City, Mo. are up 20 percent compared with a year ago. The number of flights is the same, but the airline is flying bigger planes.

Schubert cautioned against getting "lost in the percentages. Even as much as we've grown in Los Angeles this summer, Los Angeles for us is about 220 departures a day. Philadelphia is still, even though it's come down a smidge, about two times the size of Los Angeles as a hub."

"I'm only the guy who plans the route network," he added. "But my view of the world is that we have a very strong commitment, both historically and going forward, to Philadelphia as a hub."

lloyd@phillynews.com

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@LoydLinda