A huge airline merger may be in the making, a deal that would change the face of the industry and send shock waves through metro Atlanta.

The outcome of Delta Air Lines' possible marriage with either Northwest or United is hard to predict because the details — if there are any yet — are unknown.

Still, experts last week said the contours are not hard to see. The fortunes of the companies, employees, economies in the headquarters cities, consumers and shareholders will vary.

From the standpoint of the airlines' operators, the aim of a merger would be to eliminate overlaps and cut costs, while extending the merged company's reach. Simply from its size, the company would hope to find ways in which it could act more cheaply than before the merger, said economist Kenneth Button of the School of Public Policy at George Mason University in Virginia.

"You can draw up nice little business plans that have synergies," he said. "You can find economies of density, of scale, of scope. You can also find economies of market presence."

Any attempt to integrate two companies must confront obstacles, said Button. But the challenge for airlines is typically tougher than for other companies, he said, because attitudes and expectations are different — not to mention the size of paychecks.

"The problem with mergers is that they all have their own operating practices, their own ethos," he said.

Unionized companies — like Delta and the other large carriers — have their own dynamics, said Joakim Karlsson, professor of aviation management at Daniel Webster College in New Hampshire. Meshing different companies means mixing two different histories of relationships between work force and executives.

"They tend to have very deeply ingrained labor-management culture," he said. "The classic example is, how do you handle the seniority of the air crews?"

Short-term gain?

Complicating the equation is the likelihood of morale-sapping layoffs — which are, after all, part of the reason for the merger in the first place. Where the cuts come is, naturally, a matter of where the two partners have overlapping routes and a question of who gets the headquarters.

Most analysts agree that Atlanta will continue to be a major hub for air travel, merger or not. But changes are possible. A shift of headquarters, for example, could transfer hundreds of high-paying jobs out of town.

The spending that would subtract would probably mean elimination of two other Atlanta jobs for each Delta job, said Rajeev Dhawan, director of the Economic Forecasting Center at Georgia State University.

But it's not just the human element. Two technologies must also be meshed, for reservations, baggage handling and other functions.

More than that, there can be a clash of business models. Airlines like Delta are based around hub airports. Airlines like AirTran or Southwest tend to be more selective about which cities to serve. Delta can avoid the turbulence of combining different models and then face trouble later on, suggested Marty Anderson, a senior lecturer at Babson College in Massachusetts.

"This is almost identical to what GM, Ford and Chrysler have done for decades — they close some plants, which gives them a reprieve, but they did not change the fundamental business model," he said. "Merging two outdated, high-cost, hub-spoke airlines is not likely a path to long-term success."

The long-term worth of mergers is questionable, said economist George Hoffer of Virginia Commonwealth University. Often, the lion's share of the benefit falls to those who sell their stock or to the bankers who make the deal happen.

"The rewards of the deal are in the deal," he said.

A merger eliminates one competitor from many markets: Prices are likely to rise.

"It's hard to see how the consumer benefits because the airlines have basically exhausted most of the economies of scale," Hoffer said. "The consumers end up being losers. They'll have less choice, less price competition."

But if the merged company tries to take advantage of reduced competition, it will invite a challenge, argued Ilker Baybars, professor of operations management and deputy dean of the business school at Carnegie Mellon University in Pittsburgh. "If Delta merges with Northwest or United and they start overcharging the passengers, someone is going to enter the market as a competitor, and it won't be a problem for consumers."

Whatever happens to prices, there should be some benefits for consumers — especially those who travel a great deal. They will have more places to go and more chances to add to frequent-flier miles or use them.

Yet investors might wind up dissatisfied, said mergers-and-acquisitions attorney William Venema, a managing partner at Epstein Becker Green Wickliff & Hall.

Shareholders of the target company are more likely to prosper than those of the acquirer, he said. The shareholders in the acquired or target company benefit from the hope that the deal will prove profitable and can realize a premium for their stock right away. But investors in the acquiring company take a hit if the deal falls short of expectations.

Few good guides

Airline merger history is somewhat checkered. Perhaps the most critiqued deal was America West's purchase of US Airways in 2005. The buyer kept the US Airways name on the letterhead but moved the headquarters to Arizona. Besides that, there have been no major combinations.

For its part, Delta has been involved in a handful of mergers, the most recent a 1987 absorption of Western Airlines that was widely regarded as one of the most successful airline unions. In 1991, however, it suffered major financial indigestion and cultural upheaval after a partial buyout of Pan Am, a deal that stopped short of a true merger but featured many of the challenges.

Across all sectors, many a merger is poorly planned, Venema said. "Sometimes they reach for a merger to get them out of trouble and they really haven't thought through the integration strategy at the other end.

"It looks good on paper, but it doesn't work out well."