The discount airlines, however, have their fans. Traffic jumped 77 percent on Spirit and 39 percent on Allegiant from 2011 through 2014. Travel is up by double-digits again this year on both airlines.
Even passengers on other airlines might owe the discounters some gratitude. By keeping base fares low, they prevent the major airlines from pushing prices even higher—at least on the routes they compete on—says John Kwoka, a Northeastern University economics professor who studies the airlines.
Loyal customers say you can avoid most fees and save money on the budget carriers if you pay attention to the rules.
"I've been on American Airlines, Frontier, Spirit—it's all the same as long as I get to where I need to be," Larry D. Wallace, a college student from Dallas, said on a recent Spirit flight from Dallas to Denver. "I've never had a complaint with Spirit. They're cheap; they're on time."
Wallace, who said it was his fourth trip on the budget carrier, saved money by not bringing a bag. And his flight was just about perfect. The Airbus A320 was clean and brand-new—Spirit's fleet averages about five years in age, much younger than most U.S. airlines—the flight attendants were cheerful and efficient. The flight arrived in Denver 15 minutes late, but no one seemed to mind.
Executives at the discount airlines and some industry experts dismiss the government's complaint figures. They point out that very few passengers bother to file a complaint with the Department of Transportation—even at Spirit and Frontier it's fewer than one passenger in every 10,000.
That can make for volatile figures. But ironically by the airlines' own admission, the government numbers don't tell the full story of passenger unhappiness.
Frontier CEO Barry Biffle says his airline gets about 30 complaints for every one filed with the government. It used to 90-to-1, he says.
Biffle says the official complaint rate just measures how many customers find the website to lodge a complaint and they're getting more savvy about that. But if airlines had to report all the complaints that they receive directly from consumers, the numbers would be even more damning.