Faced with higher fees and larger fares, travelers are fed up with paying more and getting less from major airlines, according to a recent private economic survey released on Tuesday by the American Customer Satisfaction Index (ACSI).

ACI was started at the University of Michigan, but is now maintained privately and shows a decade of consumer trends by industry.

In all, airlines have the lowest score of any industry group, just beating out the federal government and subscription TV providers. The industries that ranked the highest were electronics, express mail, and soft drinks.

On Tuesday, the group said that Southwest Airlines gets top scores for customer satisfaction among airlines, but passenger satisfaction with airlines dropped another 1.5 percent to an ACSI score of 65 - a very low score that keeps getting worse, the group says.

Many point to the recent pay policy many airlines have adopted for checked baggage for the low scores.

Passengers who pay for checked bags are much less satisfied than those who don't (an ACSI score of 58 compared to 68), the group says. They also are more dissatisfied now than a year ago (-3%). Since nearly half of all fliers pay bag fees, the negative impact on their satisfaction is significant.

Behind Southwest in the survey, Continental scored 64, American 63, United and US Airways tied at 61 and Delta dropped to 56 on the ACSI scale.

Why is Southwest on top?

Southwest continues to reap top customer service ratings -- and a score of 81 -- in part because it has not taken anything away from customers and then offered it back for a fee, said ACSI managing director David VanAmburg.

Now it's the Deltas and Uniteds and Americans that have to act like Southwest has for years, said VanAmburg of Southwest's minimalist service model.

The good news comes as Southwest celebrates its 40th birthday. You only turn 40 once, Southwest Airlines says on its online sale page. Today, the Texas-based airline launched an autumn airfare sale with one-way fares of $40, $80, and $120 depending on how far you fly.

If you're looking for a bargain, act quickly. The offer is only good until Thursday, and is for travel between Aug. 23 and Nov. 16. Blackout dates apply and the website is quite slow due to the recent spate of interest.