Amazon has become a retail powerhouse in part because of its promise of two-day delivery on millions of items. But now some of the pilots who transport the company’s packages are speaking out against what they describe as low wages, shoddy maintenance and stalled contract negotiations

Roughly two dozen pilots in crisp white uniforms picketed on a busy thoroughfare near the Greater Cincinnati Northern Kentucky International Airport on Thursday, calling for better pay and benefits, and less erratic schedules. They held signs that said “Amazon: Driving down living standards of U.S. pilots” while passing motorists honked. The protest, organized by the Airline Professionals Association Teamsters Local 1224, comes weeks after an Atlas Air flight carrying cargo for Amazon crashed in Texas, killing all three people on board.

“Work has exponentially increased," said Mark Bly, who has flown for Atlas Air for 20 years and says he hasn’t received a raise in nearly a decade. “It was once a sleepy carrier. Now there is more work than ever."

Griffith says that the average salary of a pilot with the rank of captain is $300,000 at FedEx and $350,000 at UPS. By comparison, he said, pilots who deliver for Amazon make 40 to 60 percent less than that.