A U.S. federal judge on Wednesday ordered striking pilots back to work immediately at cargo airline ABX Air, whose major customers include DHL and online retailer Amazon.com.

ABX said in a statement it expects flights to resume immediately.

DHL said operations have resumed at the DHL Americas Hub after its airline partner ended its work stoppage and pilots have returned to work.

DHL expects its operations to start returning to normal Thursday and all delayed shipments to be delivered by the weekend, a spokeswoman said.

“Absent an injunction, ABX, its customers, and the public will suffer immediate, irreparable harm. Imagine Christmas without Amazon!” wrote Judge Timothy Black of the U.S. Court for the Southern District of Ohio.

 

Friday marks the traditional start of the holiday shopping season in the United States with the following week one the busiest for online retailers.

The pilots, represented by the Teamsters union, walked off the job early Tuesday over what they said were violations of the collective bargaining agreement with the unit of Air Transport Services Group atsg .

Judge Black said there was “no evidence” to support claims by the Teamsters who represent ABX’s pilots that the airline had violated the terms of its collective bargaining agreement with the union.

He ruled in granting a temporary restraining order that this was a “minor dispute” and was thus subject to arbitration rather than a matter for a federal court.

The union said on Tuesday that due to a pilot shortage, ABX Air had asked them to work emergency hours over the last two years, but then failed to grant them compensatory time off or allow pilots to take earned vacations as per their contract.

“As professional pilots, we’re committed to serving our customers with integrity, and we simply want ABX executives to treat us with the same respect,” Rick Ziebarth, a pilot and executive council chairman, Teamsters Local 1224, which represents ABX pilots, said in a statement on Wednesday.

The work stoppage came at a critical time for the likes of Amazon amzn and Deutsche Post dpstf unit DHL, in the run up to the U.S. holidays.

DHL had warned of delays to inbound and outbound shipments to portions of the Americas through Thursday as a result of the stoppage.

Amazon spokeswoman Kelly Cheeseman said, “We rebalanced capacity across our network of carrier partners to ensure there are no disruptions through the busy holiday weekend, and plan to leave these adjustments in place.”

Amazon has contracts with the major U.S. package delivery companies United Parcel Service ups and FedEx fdx , giving it alternatives to ABX.