Some 250 pilots, who are represented by the Teamsters union, went on strike in the early morning, affecting around 75 flights, mostly for Amazon and DHL, a unit of Deutsche Post AG.Pilots went on strike because ABX, owned by Air Transport Services Group Inc, has violated its contract by asking them to work emergency hours over the last two years because of a staffing shortage, but then failed to grant them compensatory time off or allow pilots to take earned vacations, the union said.

“Our pilots are striking so that we can have the status quo of our contract restored, and we would like that to be in the next minute so we can return to serving our customers,” said Tim Jewell, a pilot and secretary treasurer of Teamster Local 1224, which represents ABX pilots. “But if the company chooses not to do that our members are prepared to continue striking.”Air Transport Services Group said in a statement that ABX was taking multiple steps to tackle what it called an “illegal work stoppage” including seeking a court order to get the pilots back to work.”We expect the court will uphold our position that the actions taken by the union to refuse work assignments is not legal, and the issues involved constitute a minor dispute to be resolved via arbitration under terms of our current labour agreements,” ABX Air President John Starkovich said in a statement.ABX is notifying customers so they can make alternative arrangements.The strike comes just ahead of Cyber Monday, which is the biggest day of the year for internet shopping and is expected to break records this year.Amazon said it has contracts with the major U.S. package delivery companies United Parcel Service Inc and FedEx Corp, giving it sufficient alternatives to ABX.”We work with a variety of carriers and are confident in our ability to serve customers,” Amazon spokeswoman Kelly Cheeseman said in an email.DHL, however, said the strike had affected deliveries of goods into the United States.”Due to a work stoppage affecting our airline partners, inbound deliveries to portions of the Americas will be delayed today,” the company said in a statement. “We are continuing to monitor the situation.”