Consumer complaints against airlines are rising even as the carriers get slightly better at staying on schedule.
The U.S. Department of Transportation said Monday that it received more complaints from consumers in March than it did in either the previous month or March of 2014.
While the numbers are still very small — only about one in every 50,000 passengers complains to the government — they vary greatly among carriers.
Passengers on Frontier Airlines are 34 times more likely to complain than passengers on Southwest Airlines, which has the lowest complaint rate. Spirit Airlines has the second-worst rate.
The government says 78.7 percent of flights operated by the 14 largest airlines arrived on time in March, up from 72.8 percent in February and 77.6 percent in March 2014.