Airline Passengers Rank United Among Worst For Service, Southwest Best

This is really an apples to oranges comparison. Yeah, I can see that leisure travelers might like WN, but for business travelers WN's lack of assigned seats plus no upgrade potential puts it close to the bottom of my list. (I have never flown Spirit etc.)

To paraphrase GEICO "Everybody knows that! "

I'm not surprised! Been there....done that. All the Unions want is " your " dues....in other words...your money.

Anyone surprised that the non-union airline has the best service?

No surprise here! Southwest rocks!

"It found Florida-based Spirit Airlines generated the most complaints by far. The runner-up for most of the five-year period was United Airlines."

Yes, that means Spirit is the worst and United second worst.

"complaints against United spiked in 2012, in the wake of its merger with Houston-based Continental."

No link to where the article lists other carriers - like DAL, AAL, USA etc - which are near the bottom as well.

This is typical statistics garbage. It's sound bite fodder for people like Matt Jensen who don't take the time to read the article and see what the data is based upon. ie DAL, AAL and USA are not all on the bottom. DAL was 11 of 13 beat by SWA and Alaska.
1) This only accounts for the passengers who complained to the DOT. Nowhere does it state it the complaint is valid.
2) In 2012 609,491,874 enplanements with approx 11,445 complaints. What's that 0.002%? The average per 100K for 5 years is only 1.85 and only 1.22 if you remove Spirit.
3) What is does show are airlines under bankruptcy have poor service
4)With the latest wave of consolidation, airfares declined about 50% from 1980 to 2009, but have increased rapidly since 2010 especially when fees and taxes are included.
5) So you get what you pay for and the government need to quite taxing the airlines