NEW YORK – In the past eight years, as the airline industry experienced a flurry of mergers, escalating fuel costs and a global recession, many airports that experienced deep cuts in service have seen steep spikes in fares.

A USA Today Network analysis of the top 100 airports in the 48 contiguous states found that on average, those that lost at least a quarter of their domestic seats since the start of 2005 saw nearly twice the average fare increase.

That trend worries some industry watchers as American Airlines heads to court Monday to get what will likely be the final approval needed to close its merger with US Airways.

Past mergers have resulted in the new partners shedding some hubs and cutting flights at some airports as they focus on more profitable routes and portals.

“You see flight reductions, personnel reductions, service reductions and fare increases,” says Brent Bowen, dean of the College of Aviation at Embry-Riddle Aeronautical University’s Prescott, Ariz., campus. “When these airlines merge and combine … you’ll see former hubs not being hubs anymore.”

Merger imminent

Representatives of American Airlines, which has been under bankruptcy protection since November 2011, are scheduled to head to bankruptcy court Monday in New York City to get approval for the company’s restructuring plan. A green light would clear the way for it to finalize its merger with US Airways, a deal that will create the largest airline in the world.

The two airlines reached a settlement this month with the Department of Justice, which sued to block the tie-up but backed down when the airlines agreed to give up dozens of take-off and landing slots at New York’s LaGuardia and Ronald Reagan Washington National airports.

American and US Airways said they would maintain their hubs in Los Angeles, Charlotte, New York’s JFK, Miami, Chicago O’Hare, Philadelphia and Phoenix for three years. They have committed to keep their merged headquarters in Dallas-Fort Worth for the same time period.

The cutbacks in service that have hit most of the top 100 airports in the past eight years reflect an industry that’s been transformed as it’s tried to stay afloat. Onetime rivals have merged, allowing them to focus on bigger, more profitable hubs, and airlines have become extremely disciplined, careful not to fly more seats in a market than they can profitably fill.

“That’s what consolidation has allowed them to do, because they can generate the same amount of revenue doing less of the flying,” says William Swelbar, a research engineer with MIT’s International Center for Air Transportation.

Fewer flights in a market generally means higher ticket prices.

“Inevitably, fares get squeezed, and they rise,” says Henry Harteveldt, a travel analyst with Hudson Crossing.

Flights disappear

Cincinnati remains a Delta hub, but its domestic flights have shrunk in the wake of Delta declaring bankruptcy in 2005 and then merging three years later with Northwest, which had an overlapping hub in Detroit.

USA Today’s research found that Cincinnati/Northern Kentucky International Airport saw its seats plummet 80 percent between the first quarter of 2005 and the first quarter of 2013, as Delta slashed flights and the airport lost service from Northwest as well as Continental, which merged with United in 2010.

Fares spiked 26 percent during that eight-year period, to an average ticket price of $519 — the highest of the 100 airports reviewed.

“Delta was using Cincinnati in the same way Northwest used Detroit,” Swelbar says. “They consolidated those (traffic) flows around Detroit.”

Indianapolis International Airport saw domestic fares increase 23 percent between the first quarters of 2005 and 2013, and its domestic seats plunged 39 percent.

The airport suffered deep cuts in air service and saw fares escalate after ATA, a dominant carrier there, went into bankruptcy and eventually folded. Cutbacks continued when Northwest shrank its Indianapolis mini-hub after joining forces with Delta.

High jet fuel prices, a key reason airfares increase, also had an effect in Indianapolis. But this year ticket prices finally started to stabilize and several carriers are adding new routes, including non-stop service between Indianapolis and Los Angeles, San Francisco and Trenton, N.J.

The agreement by American and US Airways to give up slots at LaGuardia and Reagan National will reduce some service between those airports and smaller cities. But they might add flights between those communities and their other hubs, such as Philadelphia, Harteveldt says. Additional service could lead to lower fares, and wherever American and US Airways exit, lower-cost carriers could enter.

When all is said and done, some industry experts say, airline tickets can only surge so high.

“Airlines know they can push fares only so far,” Harteveldt says.x