The union representing FedEx pilots unanimously approved a strike authorization vote last week, according to a Wednesday press release.

Contract negotiations between FedEx management and the FedEx Express Master Executive Council of the Air Line Pilots Association International have stalled, with no future talks scheduled, the release said.

“The decision to move closer to a strike authorization vote is the result of nearly six months of federally mediated negotiations that has led to our disappointment with FedEx management’s actions at the bargaining table,” said FedEx MEC chair Captain Chris Norman.

FedEx pilots have been in negotiations with management since May 2021. According to a statement on the FedEx pilots’ website, pilot leaders allege the company has failed to “acknowledge pilot contributions.”

“ALPA leadership’s approval to possibly conduct a strike authorization vote at some future time has no impact on our service as we continue delivering for our customers around the world,” FedEx said in a statement.

Tensions have been high as the airline industry rebounds from the Covid-19 pandemic, leading to record losses of around $35 billion in 2020. Contract talks with pilots and flight attendants were further derailed by the pandemic, all while the industry faces a pilot shortage and rising costs.

A strike would occur only if negotiations break down and the federal government authorizes a walkout following required procedures of the Railway Labor Act. Both sides would have to be released from mediation by the National Mediation Board, which was brought in to assist with contract negotiations in October.

After 30 days, pilots and management could exercise self-help, which could include a union strike or a company lockout.

“FedEx pilots are committed to reaching a deal with management, but we will not waiver in our commitment to deliver a contract that rewards pilots for their sacrifices to build FedEx into the global leader it is today,” Norman said. “Although a strike authorization vote has not been called at this time, our customers and shareholders should be aware that the pilots may be headed in that direction shortly.”

A statement by pilot leaders says FedEx customers should plan alternative means in the event of a pilot strike. Only a few items for negotiation remain, the statement says.

The update comes a month after the Southwest Airlines pilots’ union called a vote to authorize a potential strike after souring contract negotiations. Delta Air Lines pilots also voted to authorize a potential strike in November.

Unions representing about 30,000 pilots combined at American Airlines and United Airlines rejected potential contracts in November.

— CNBC’s Leslie Josephs contributed to this report.