The airlines Americans love to hate

The airline industry is one that Americans love to hate, but some carriers get singled out for special levels of scorn.

The airline that gets the lowest marks for customer service by American travelers is Spirit, according to the the American Customer Satisfaction Index (ACSI), an independent national benchmark of consumer experiences of products and services sold to U.S. consumers. While Spirit sells itself via low prices, travelers aren't too thrilled with the overall flying experience on the airline, which bills itself as "home of the bare fare."

Of course, consumers overall aren't too thrilled with the entire airline industry, ranking it only above Internet service providers, cable-TV and other subscription TV providers, and health insurance. As a benchmark, even the U.S. Postal Service gets a higher score for customer satisfaction than the airline industry, according to the ACSI's report.

But within the airline segment, clear winners and losers emerge, with Spirit ( SAVE) and Frontier Airlines, another low-cost carrier, landing at the bottom.

"At the end of the day, flying is just not the most pleasant experience," ACSI director David VanAmburg told CBS MoneyWatch. Spirit and Frontier are among the discount carriers that are "known for low prices and very little else. If you want what service is available, that comes with fee after fee after fee."

Even after adding in optional fees such as seating assignments and snacks, Spirit's prices remain about one-third lower than other airlines, Spirit spokesman Paul Berry wrote in an email. "This study (and others like it) looked at several airline features except the one that air travelers care about most -- price," Berry wrote. "We do our best to let people know how we are different through our website at Spirit.com, and that difference saves them hundreds of dollars on air travel."

Fees and uncomfortable seats lead consumers to feel unhappy, the survey found. While the seating on airlines isn't likely to change, given that carriers won't want to give up seats and revenue just to give passengers more space, charging fees for everything from baggage to food is a clear path to creating dissatisfaction, VanAmburg said.

The airlines "could make their rates $50 higher and give everyone one free bag, and the customers would be happier," he noted. "The notion is upside down in the industry -- that we should make fares low and charge for everything else -- because then consumers really feel they are being nickeled and dimed."

At Spirit, for instance, fees now account for 41 percent of its revenue, the study noted. Because Spirit competes on price alone, consumers will opt to fly on it even though they might not like the experience, VanAmburg said.

"We have one of the highest load factor (full planes) in the industry," Spirit's Berry noted. "If the survey was based on what people do, rather than what they say - and looked at price as what consumers want most (as almost every passenger survey suggests) then I'm confident we would do much better in such surveys."

One airline flies far above the rest, however: JetBlue ( JBLU). The ranking found that JetBlue has climbed in consumers' estimation in the past year, scoring 81 points this year compared with 79 points in 2014. The lowest-rated airline, Spirit, earned just 54 points.

"What they like about JetBlue is that it's a discounter like Spirit, but still with a level of quality that's closer to the legacy airlines," VanAmburg said. That middle-level of service, combined with a perception of value, has helped push JetBlue to the top of the rankings.

But turbulence may be lurking ahead, VanAmburg noted. JetBlue is planning to add baggage fees and to squeeze more seats into its airplanes, which he said he expects will erode its performance next year. At the time when the ACSI conducted its current airline survey, the baggage fees hadn't yet been implemented.

Here's the ACSI's ratings for airlines, ranked from top to bottom, with their consumer satisfaction scores in parentheses.

1. JetBlue (81)
2. Southwest (78)
3. Alaska (75)
4. All others (73)
5. Delta (71)
6. American (66)
7. Allegiant (65)
8. United (60)
9. Frontier (58)
10. Spirit (54)