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Stranded United Airlines passengers attempt to access the self check-in computers at the United Airlines terminal after the computer system came back up at Los Angeles International Airport. - 

JEREMY HOBSON: Now to the not-so-friendly skies some passengers experienced over the weekend. Many flights were cancelled and about a hundred were delayed not because of weather or a problem with the planes. But because of a computer glitch at United Airlines.

Marketplace's Eve Troeh reports.

EVE TROEH: United Airlines passengers stared at blank arrival and departure screens Friday night. Then lined up for hours to get hand-written boarding passes.

Cranfield School of Management economist Sean Rickard flew from JFK to London Saturday. He wasn't on United, but their angry customers were everywhere.

SEAN RICKARD: People felt they hadn't been kept informed. They hadn't been treated very well. Was just horrendous. And that was the day after it happened.

He says this type of accident could hit any airline. It's United's response to the computer failure that's most troubling and will lose them customers.

RICKARD: How many years is it going to take to get them back again? So the damage can be enormous.

U.S. Airways saw a three-hour computer crash Sunday morning. It did not cancel any flights.

I'm Eve Troeh, for Marketplace.

Follow Eve Troeh at @evetroeh