What’s not to love about flying domestic?

A lot, apparently. According to statistics released by the Transportation Department, passengers filed 20 percent more complaints against U.S. airlines in 2015.

USA Today reports that 9,542 complaints were lodged during the first six months of the year. In comparison, 7,935 grievances were made during the same period in 2014.

The top causes are cancellations, delays, and missed connections – all of which add up to 3,107 complaints. Passengers submitted 1,417 complaints about baggage, 1,282 in regards to ticketing and boarding, and 1,121 were about customer service.

American and United garnered the most complaints, with 1,540 and 1,271, respectively.