MIAMI — Atlas Air and FedEx Express have entered into a five-year capacity support agreement, intended to add extra cargo capacity during the peak flying seasons from 2017 through 2021.

According to the terms of the agreement, Atlas Air would provide FedEx with five Boeing 747-400s, which will operate temporarily for the parcel carrier during December “and potentially earlier.” Both companies have in place an agreement to provide five aircraft during this year’s peak season.

“We have worked closely and successfully with FedEx for many years, but this is our first agreement that allows both companies to plan for the longer term,” said William J. Flynn, Atlas Air President and Chief Executive Officer.

The company posted revenue of $443.27 million in the 2Q 2016 period, a decrease of 2.8% compared to the same quarter last year, largely attributed to an increase in military cargo and passenger demand but a slower pace in general commercial cargo demand, the company said.

Second-quarter expenses rose 7.1% year-over-year (YOY) to $422.4 million, reflecting start-up expenses associated with the company’s upcoming long-term 767 service agreement with Amazon.

Last May, Atlas Air and e-commerce giant Amazon rolled out the first Prime Air 767-300 freighter, the first of 40 freighters that Amazon agreed to lease through air cargo partners Atlas Air and Air Transport Services Group (ATSG).