SEATTLE, Wash. (KOIN) — After three years of failing to come to a contract agreement, the Alaska Airlines pilot’s union leaders voted unanimously to conduct a strike-authorization ballot among their pilots.

The vote comes during a pilot shortage, which has forced Alaska Airlines to cancel hundreds of flights this year.

Once the vote is passed by the pilots, it would officially authorize pilot leadership to declare a strike when the group is permitted to do so by the National Mediation Board (NMB). However, this would only take place if negotiations break down and a walkout is authorized by the federal government after both parties exhaust the required procedures of the Railway Labor Act.

The strike authorization opens on May 9 and closes on May 25.

“Alaska pilots are not looking to strike. We are looking for improvements to our contract in line with the market but that will also allow our company to grow and remain successful and competitive,” said Capt. Will McQuillen, chairman of the Alaska Airlines Air Line Pilots Association Int’l (ALPA) MEC. “However, we are willing to take any lawful steps necessary, including a legal strike, to achieve the contract every Alaska pilot has earned.”

The strike authorization vote comes more than a month after 1,500 Alaska pilots held an all-base picket on April 1, the largest picket in ALPA history. Dozens of Portland flights were halted due to the picket.

“We lag behind our peers in several significant areas which has resulted in dozens of pilots leaving for better career opportunities elsewhere,” McQuillen said. “If Alaska Airlines management wants to run a competitive airline with ample growth, then they need to get serious about reaching a new pilot agreement that’s competitive that provides job security, stronger work rules, and enhanced quality-of-life provisions that provide flexibility and reasonable schedules.”

The NMB would have to release the two sides from mediation before a strike could take place. After a 30-day cooling-off period, a strike by the union or a lockout by Alaska Airlines could take place.

In February, Alaska Airlines said they presented their most generous contract offer in history to the pilots, saying that the proposal was “in line with industry peers in important areas and included many industry-leading components across compensation and work rules.”

For more information regarding Alaska pilot negotiations, visit their website.