Frontier Airlines pilots have voted to authorize a strike, the Air Line Pilots Association said today.

The ALPA also said 99% of the votes cast were in favor of the strike. According to its website, the ALPA covers 2,200 pilots at the carrier.

While the strike authorization does not guarantee a work stoppage, it is a vital tool in negotiations.

Frontier pilots’ contracts became amendable in January and have been engaged in mediated talks under the Railway Labor Act since then.

“Negotiations for a new collective bargaining agreement have yet to yield a market-based contract that aligns with industry standards,” the ALPA said.

The announcement comes at a time when unions across the U.S. are pushing for better pay and work conditions.