Travelers are confronting another miserable day at the nation's airports today, as American Airlines canceled more than 920 flights.
The airline is rotating the planes back into service once inspectors re-examine wiring. Of its 300 MD-80 series jets, American expects to have 130 of them back in service by Thursday afternoon. The carrier expects all of them to be returned to service by Saturday night.
"I take full personal responsibility for our being in this situation," American's chairman and chief executive, Gerard Arpey, said Thursday.
But American's decision to cancel flights today in addition to the more than 1,000 flights it canceled Wednesday for last-second inspections is just one of many headaches for travelers -- and for a struggling airline industry -- already facing a steady stream of problems.
Now industry experts say several of the airlines' problems are rooted in one underlying issue: aging planes.
Those recently reinspected are some of the oldest planes that U.S. airlines are flying today. While the planes may be safe, the older they get the more likely they are to have maintenance problems, causing another catastrophic delay.
"They've been putting off modernizing the fleet," said Ray Neidl, an airline analyst with Calyon Securities. "At some point it's going to put the U.S. carriers at a big disadvantage to foreign carriers. It's going to drive up their operating costs because these aircraft tend to be less fuel-efficient and require greater and greater maintenance."
Of roughly 4,400 airplanes worldwide that are 21 years or older, half of those are in the United States, according to John Stilmar, an analyst with Friedman, Billings, Ramsey & Co., who follows the airplane leasing business.
In September 2001, the average age of American Airlines' aircraft was 11 years old, according to a report by Stilmar. By the end of 2006, the average age of the fleet American was flying was 14.
"We're witnessing a system in desperate need of new advanced technologies in the air and increased capacity on the ground," said Rep. Thomas E. Petri, R-Wis., at an aviation hearing Wednesday on Capitol Hill.
Still, faced with financial struggles, U.S. carriers have no major public plans so far to replace their older aircraft.
Rick Seaney, CEO of FareCompare.com and an ABCNEWS.com columnist, said that no major legacy airline is taking delivery or even ordering new planes for domestic service.
That keeps older, less fuel-efficient planes in service longer than carriers would like.
"The airlines are hoarding any cash once used to refresh the fleet, to prepare themselves should oil prices continue to go higher," Seaney said.
But as U.S. carriers hold off on the upgrades, foreign carriers are investing in improvements.
The bulk of the sales for new aircraft being manufactured by Boeing and Airbus -- the world's two largest plane manufacturers -- is coming from Europe and Asia, putting U.S. airlines at a strategic disadvantage in the years ahead.
For example, in January 2007, Australia's Qantas airlines announced plans to order nearly 190 new planes from Boeing and Airbus to use on its short-haul domestic routes and to expand low-cost flights to Southeast Asia. The airline operates about 210 aircraft.