(Reuters) - Southwest Airlines Co pilots' union said on Thursday its members had approved a strike mandate by an overwhelming majority ahead of the busy summer travel season.

The Southwest Airlines Pilots Association (SWAPA), which represents 10,000 pilots of the Dallas-based carrier, said 98% of its members participated in the vote and 99% voted in favor of authorizing a strike.

Southwest said the vote result will not impact its operations: "We are staffed and prepared to welcome travelers for their summer travel plans."

Southwest has been under regulatory scrutiny since a staffing crisis due to bad weather during the Christmas holidays overwhelmed its crew scheduling software, disrupting travel plans for 2 million customers.

"Pilots (have) already made their voices heard about the operational disasters and the lack of progress after three-plus years of stagnant negotiations," SWAPA said.

Earlier this month, pilots of American Airlines Group also approved a strike mandate.

(Reporting by Aishwarya Nair in Bengaluru; Editing by Vinay Dwivedi)