(Bloomberg) -- Southwest Airlines Co.’s flight attendants approved a new $6.3 billion labor contract, setting a standard that could influence talks at other US carriers.

The four-year agreement will provide an initial 22.3% pay raise, followed by three annual increases of 3%, the Transport Workers Union local 556 said in a statement Wednesday. The pact was approved by 81% of those voting, according to the union, which represents 21,000 Southwest workers.

The contract, replacing one agreed to in 2019, is the first for flight attendants at a large US carrier in the latest round of talks. The terms will likely draw notice from workers in similar negotiations at American Airlines Group Inc. and United Airlines Holdings Inc.

“For far too long, flight attendants across the aviation industry have had to fight to improve our compensation and quality of life,” Lyn Montgomery, TWU 556 president, said in the statement.

Labor and fuel are the top expenses for airlines, and flight attendants are the 11th Southwest work group to approve a new contract since October 2022. The agreements provide certainty going forward for the carrier’s budgeting process. Southwest pilots in January approved a new agreement that will boost pay 50% on a compounded basis over five years. 

Flight attendants will split a pool of at least $364 million for ratification bonuses based on time worked during the years the accord was being negotiated. The contract includes improved health-care benefits, better pay for situations including irregular operations or an extended duty day, holiday pay on July Fourth, Memorial Day and Labor Day and what the union said is an industry first for paid maternal and paternal leave.

The $6.3 billion valuation was provided by the union, while Southwest noted the figure includes all compensation for the life of the contract. The airline said in a separate statement that the contract becomes amendable in 2028.

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