Between January and June this year, the U.S. Department of Transportation logged 9,542 consumer complaints, which was up 20.3 percent from the first half of 2014. In June, complaints shot up 50 percent over last year.
Part of the problem is that complaints against widely reviled carrier Spirit Airlines were included in the tally for the first time. It and Frontier now have five times the complaints than the industry average.
Spirit may be leading the pack in disgruntled customers, but it doesn't let its dubious achievements end there: It's also near the top of the list for late flights. A quarter of its flights were late 70 percent of the time or more. United Airlines did poorly, too: A third of its flights were late.
Hawaiian, Alaska, and Delta were the most punctual in June, as the summer travel season began. JetBlue and Virgin America were the best in baggage handling for the same month.