Atlas Air Worldwide Holdings and the International Aviation Professionals (IAP) union have offering differing views on the progress of talks to settle the five-year dispute over pilot contracts.
Following the announcement of its half-year results, the aviation company said that it expects the arbitration process to conclude in the second half of this year.
The airline and union have been in talks over merging Atlas Air and Southern Air pilots onto a single contract since the latter was acquired by Atlas in 2016.
"We remain committed to reaching a new Joint Collective Bargaining Agreement (JCBA) with our Atlas Air and Southern Air pilots, and have moved closer to completion," Atlas said.
"Scheduled arbitration hearings concluded on April 1 and the union has now provided the company with the integrated seniority list, which is a critical item for implementing the new JCBA.
"The next step is for both parties to submit post-hearing briefs. The arbitrator will then consider all of the information presented and render a binding decision, which we expect in the second half of this year."
However, the IAP accused the freighter leasing giant of continued stalling tactics.
Robert Kirchner, head of IAP Teamsters Local 2750, said: "Delay, delay, delay are the only words Atlas managers know when it comes to getting a contract done with its largest and most important work group.
“Atlas executives have made the calculated choice to hand over key decisions about the future financial and operational direction of the airline to a third-party arbitrator, washing their hands of any responsibility.”