ATLANTA (AP) — Pilots at Delta Air Lines voted to authorize union leaders to call a strike, but it might be a largely symbolic gesture, as hurdles remain before the pilots can legally walk off the job.

The Air Line Pilots Association said Monday that 96% of Delta pilots took part in the vote, and 99% of those favored calling a strike “if necessary” to get a new contract.

Airline unions are seeking big pay increases and could have leverage because of labor shortages during a rebound in travel.

Atlanta-based Delta said the vote would have no impact on its flight operations.

The airline said the union’s goal is “simply to gain leverage in our pilot contract negotiations.” Delta said it has made significant progress in talks, that only a few contract sections are unresolved, and it expressed confidence in reaching an agreement.

Last week, American Airlines offered its pilots 19% pay increases over two years, an offer that could serve as the model for talks at Delta and United Airlines. Leaders at American’s union have not decided whether to send the offer to a ratification vote.

Delta pilots are working under pay rates set in 2016. Negotiations for a new contract began in April 2019, were paused in March 2020 for the pandemic, and resumed in January.

By federal law, labor contracts in the airline industry do not expire. Before workers can legally strike, federal mediators must determine that more talks would be pointless. Even after that, the president and Congress can intervene to block a strike.

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