Whether the business, called Marana Aerospace Solutions, is the biggest aircraft maintenance and repair operation in the world, as new owners claim, depends on how one measures it: by maintenance capacity, airplane parking space or total square footage.

But at some 1,200 acres, it is certainly among the largest.

Relativity Capital, a private equity company based in New York, bought the business last year from Evergreen International Aviation, which used the site primarily to service its own fleet of helicopters and cargo planes. Joyce Johnson-Miller, a senior managing director at Relativity, said that recent changes in the global aviation business convinced the company that the maintenance, storage and dismantling of airliners that were either newly retired or coming off lease was an investment with good potential.

Until recently, American carriers would have sold such airplanes directly to airlines in developing countries. But as air travel booms in other parts of the world, new financing options have made it possible for even start-up airlines to buy or lease new planes.

"It's a pipeline," said Hal Heule, the chief executive of Marana. "New airplanes come in and older ones are going to pop out the other side. We're on the retirement side, which is increasing."

Airplanes have become more affordable to more airlines in part because of the increasing involvement of leasing companies. A report by Morgan Stanley Research in March found that 34 percent of the airliners in service were owned by a leasing company or financial institution, more than double the figure from 20 years ago. Leasing companies buy directly from the maker, like Boeing or Airbus; airlines will then rent the plane for a fixed number of years.

"We've observed a shift from airlines to lessors. It is something that is new," said Katy Padgett, a communications manager for Pratt & Whitney, which is a part owner of Southern California Aviation, a competing airplane maintenance operation in Victorville, Calif.

But unlike airlines, leasing companies typically do not have their own operating certificates or flight and maintenance crews. When planes return to them as contracts end, they are serviced by operations like Marana and leased again to other airlines. Those at the end of their operating lives are sold for scrap.

Other investment companies are seeing potential in the same business in the area around Tucson, where land is cheap, the air is dry and sun is a constant. Just south of Marana at the Tucson airport, the asset management company Victory Park Capital, based in Chicago, owns Ascent Aviation Services, which stores planes and maintains and repairs smaller, single-aisle airliners. One of the largest independent airline leasing companies, the International Lease Finance Corporation, bought AeroTurbine in Goodyear, Ariz., last fall so it would have its own maintenance and storage facility.

"The demand for facilities is going to draw entrepreneurs and venture capitalists," said John Goglia, an airline consultant. "It's a new phenomenon that big money has been getting involved."

Companies offering storage, maintenance and disposal services benefit from spacious, isolated locations, said David Quiero, chief executive of Ascent. Once an owner has selected where to park an out-of-service airplane, inertia weighs heavily in future decisions. There is little that is more burdensome than a plane that will not fly.

"The way I look at it," Mr. Quiero said, "getting the customer in the door is an advantage."

On a recent visit to Marana Aerospace, workers were busy hanging signs with the new name and logo above a hangar. Lou Moore, the vice president for operations, pointed out the aging air traffic control tower not far from the three maintenance hangars. A climb to the top offers an encompassing view of row upon row of parked jets.

The tower dates to the property's occupancy by the Marana Army Air Field during World War II. Other artifacts tell of the more clandestine activities that went on here after the base closed in 1948 and transferred title to the county. A driving track for teaching survival and evasive maneuvers, and firearm practice ranges are very likely a legacy of the time when the facility was used by airlines operated by the Central Intelligence Agency, according to Jason Gart, a senior historian at History Associates, a consulting company.

"They needed a place to go where they would be in the middle of nowhere and do what they had to do and practice," he said, "and that's Marana."

The commander's quarters, the enlisted men's barracks, the swimming pool and the restaurant provide modest accommodation and entertainment to Marana's customers and temporary workers. Occupying the vast space beyond all those amenities are the airplanes, some painted in the livery of well-known airlines and a few unceremoniously perched on stacks of railroad ties while their fate is being decided. Marana assumed responsibility for the planes when it bought the business.

Ms. Johnson-Miller said the decision of whether to scrap or recommission an airliner was both a safety and financial one. Marana plans to provide financial advice and repair services, she said.

Whether these airliners will see a wrench or a wrecker is noted by the presence or absence of a red X on the nose. The X means the plane's next destination will be the buzz saw. But even if it is the end of the line for the plane, it is an opportunity to turn a profit.

"Breaking airplanes up and selling the scrap metal has proven to be profitable," Mr. Goglia said. "Some of the material that's recovered is getting higher prices than it has in a long time."