With commercial airlines struggling to cut costs, they often pull aircraft out of service, putting them into storage at places like the Pinal Air Park in the Arizona desert.
There, rows and rows of airliners sit baking in the sun, their windows taped against wind-blown dust. They're perfectly serviceable -- just too expensive to continue flying.
Workers at the facility periodically start the planes' engines, much the same way one would start an old Volvo in the driveway to keep it from seizing up. NPR's Ted Robbins gets a tour of the facility.