CHICAGO — Passengers are more dissatisfied with airlines' customer service than they have been in years at a time when carriers are charging more and more for tickets and services.

CHICAGO — Passengers are more dissatisfied with airlines' customer service than they have been in years at a time when carriers are charging more and more for tickets and services.

An annual survey released Tuesday by the University of Michigan found customers giving airlines the worst grades since 2001, with the industry's overall scores dropping for the third straight year.

United Airlines and US Airways Group Inc., which are in talks to combine into a single carrier, finished next-to-last and last, respectively, in the university's American Customer Satisfaction Index.

Continental Airlines Inc. and US Airways Group Inc. registered the biggest declines from 2007.

A familiar bright spot in the results was Southwest Airlines Co., which led the industry in passenger satisfaction for the 15th consecutive year.

While unhappiness with airlines is nothing new, this year's survey produced "really dismal numbers," said Claes Fornell, a University of Michigan business professor and director of the research center that compiled the data.

"There's no other industry anywhere that has so many basic mishaps in terms of not delivering the basics," he said. "They're supposed to deliver passengers with their luggage to a particular destination within a certain timeframe, and they frequently fail to do that."

Asked why scores have worsened so significantly, he said airlines' management has to be blamed despite some factors beyond their control such as higher jet-fuel costs and congested airports.

But passengers also are not blameless, said Fornell.

"They buy primarily on price, and very little else," he said. "The result of that is very low service and a business model of cost-cutting that really leaves no one happy, certainly not the businesses, the shareholders or the flying public."