If U.S. airline passengers seem slightly more agitated than last year, it’s not a coincidence. Overall complaints lodged against U.S. and foreign airlines are up about 20% year-over-year for the first six months of 2015.

Flight cancellations and delays spurred most of U.S. travelers’ complaints but baggage dissatisfaction was the second most popular reason travelers voiced their frustrations.

Data from the U.S. Department of Transportation show there were more than one million reports filed against U.S. airlines due to mishandled baggage between January and June for the 300.1 million passengers who flew on U.S. airlines during that time. The department separates mishandled baggage reports from general baggage complaints (see chart below).

For a major U.S. airline, Southwest Airlines had the most reports for mishandled baggage (236,724) and had an average of 3.39 complaints per 1,000 passengers. The combined American Airlines-U.S. Airways, however, took the top spot with 256,927 reports and American Airlines separately received the second most reports (156,292). These standings remain the same when considering overall baggage complaints for January through June 2015.

Of the 9,542 general complaints U.S. and foreign airlines received for the first half of the year (including customer service, booking, fares and boarding) nearly one-third regarded flight problems including cancellations, delays and misconnections and 1,417 were baggage-related. American Airlines received the most complaints followed by United Airlines and this is the first year the department required Spirit Airlines to publicly report its complaints. It received 937–the third highest number of complaints for a U.S. airline.

Virgin America makes out as the ‘good guy’ with its 2,600 mishandled bag reports and 42 complaints logged during that timeframe, although that carrier had 3.3 million passengers compared to American’s 43.5 million or United’s 45.7 million.

The number of mishandled baggage reports and complaints aligns with a report earlier this year which also found the number of flight problems and baggage complaints are rising. It also coincides with reports of U.S. airlines collecting record bag fee revenues in 2014 and also the fact that Southwest is the lone major U.S. airline left not charging for the first checked bag after JetBlue rolled out its new bag policy last month.

Breakdown of U.S. Traveler Mishandled Baggage Reports vs. Overall Baggage Complaints Against U.S. Airlines for January-June 2015

AirlineNumber of Mishandled Baggage ReportsNumber of Overall Baggage Complaints
Southwest Airlines236,72486
American Airlines156,292247
Delta Air Lines127,81568
United Airlines123,316222
U.S. Airways100,63577
JetBlue Airways26,64521
Spirit Airlines20,076102
Frontier Airlines18,04183

Number of Overall Complaints Filed by U.S. Travelers Against U.S. Airlines for January-June 2015

AirlineNumber of Overall Complaints% Change over January-June 2014
American Airlines1,54077.60%
United Airlines1,271-2.70%
Spirit Airlines 937N/A
Frontier Airlines622234.40%
U.S. Airways608-15.00%
Delta Air Lines482-4.50%
Southwest Airlines 36310.60%
JetBlue Airways149-36.00%

Source: U.S. Department of Transportation

Photo Credit: Travelers wait to board a Delta Air Lines flight at Terminal 4 at New York's John F. Kennedy International Airport. Dan Peltier / Skift