Few people expect luxury while flying, but these days, even the basics seem to be in bad shape. It's not uncommon to find your tray table broken, the in-flight entertainment system not working and your seat (1) worn-all of which can make you think, how old is this plane anyway? The reality for many U.S. air travelers is that most of their journeys take place on planes that have been in service for a (2) or more. The average age of the fleet of the seven large U.S. passenger airlines is about 14 years old, according to The Airline Monitor. It found American and Delta/Northwest had the oldest fleets, at about 16 years on average. As of the end of 2008, a small percentage of the (3) Delta/North west's planes dated back to the late 1960s. U.S. fleets are among the oldest in the world, said Richard -Aboulafia, an (4) analyst. "I'm not really sure that people should read that much into that," Aboulafia said. "From a safety (5), a lot of the older planes were built tougher and with proper (6), there's no reason why a plane can't stay safe for 25 to 30 years." It's also important to remember that a plane may be 20 years old, but its engines and other major systems could have been recently (7) or upgraded, said Aboulafia. There's less pressure on the airlines to (8) the (9), unless it's a safety (10) or a redesign that will save money.