The carriers' latest composite score was 65 on a scale of 0 to 100. The average score across all industries is 74. A score reflects the total customer experience.
Scores in the low 60s indicate you're in trouble with customers, said Claes Fornell, who oversees the ACSI.
Of the seven airlines given individual ASCI scores, only one did pretty well. That was Southwest with a 74.
US Airways: 62
A difference of two or three points is not significant, given the survey's margin of error, said Fornell.
But many travelers clearly aren't happy with the legacy airlines, the nation's oldest carriers, which include Northwest, and which are struggling to respond to low-fare competitors like Southwest and market forces threatening their survival.
Labor woes and the airlines' shedding of more than 100,000 employees in recent years has been a big factor in their falling service rankings, Fornell said.
'It is not easy to improve customer service when you have fewer resources,' he said. '… And if you get rid of people, you have to make sure the people you retain are at least reasonably happy.'
Customer satisfaction is generally a good predictor of a firm's viability.
'In most industries, there's a very strong correlation,' Fornell said. 'You either change or are forced out of the market.'
But low scores often also reflect a lack of competition and choice.
With Northwest, one thing people complain about is the lack of information or inaccurate information when planes are delayed or canceled, Fornell said. People also said they wait too long to get their luggage.
But travelers really like Northwest's self-service ticketing kiosks. 'They take away the lines,' Fornell said.
In the past five years, Eagen-based Northwest has lost about $3.4 billion on its operations and cut some 20,000 jobs. Now, it's in the midst of bankruptcy reorganization and trying to wrap up a campaign to wrest $1.4 billion in annual wage and other labor saving from its employees.
But Northwest employees have 'consistently maintained their focus on meeting the needs of our customers during difficult times,' said spokesman Kurt Ebenhoch.
In the first quarter of this year, the airline has been a leader in on-time, baggage handling and other performance measures tracked by the U.S. Department of Transportation, he said.
'For many airlines, including Northwest, low fares and high costs, particularly fuel costs, have resulted in fuller flights than at any time in history, impacting customer satisfaction,' Ebenhoch added.
With airlines cutting free meals and drinks, reducing free baggage allowances and eliminating other perks in recent years, it's understandable how people would be less happy with them, said Marty Wahoske, spokesman for the North Central Business Travel Association.
As far as serving the business traveler, he'd give airlines a C+, weighing everything from the quality of their planes to scheduling.
'It could be better,' Wahoske said. 'It's improving. But we're not out of the woods.'
The American Customer Satisfaction Index tracks customer evaluations of the quality of products and services available to household consumers in the United States. It is updated quarterly with new measures for different sectors of the economy. More than 65,000 consumers are interviewed annually in developing the index.