DALLAS (CBSDFW.COM/AP) — Southwest Airlines mechanics have approved a five-year contract that adds up to a 20% raise.

Dallas-based Southwest on Tuesday announced the tentative agreement with about 2,400 workers represented by the Aircraft Mechanics Fraternal Association. Both sides in March announced they had reached a tentative deal.

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The agreement, which also calls for $160 million in bonuses, comes after six years of negotiations. Union officials say 94% of workers voted in favor of the proposal.

A Southwest statement says the new contract will become amendable in April 2024.

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(credit: Southwest Airlines)

Southwest Airlines founder Herb Kelleher passed away in January at the age of 87.

Kelleher famously came up with the idea for Southwest Airlines and its brash approach that rocked the airline industry, along with two partners, on a cocktail napkin.

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The airline started in 1971 and Kelleher served as chairman and CEO until 2008.