Spanish air traffic controllers voted to strike on Tuesday night, with a walkout scheduled to begin on August 18th, according to the Guardian.
The walkout, which would strand millions of passengers at the height of tourism season, is scheduled to last three days.
It would be the first strike by air traffic controllers in Spain. Roughly 300,000 visitors from Britain alone would be affected.
The country's 2,300 controllers are protesting against José Luis Rodríguez Zapatero, who is planning on altering their working hours and reduce overtime pay.
Controllers in Spain, meanwhile, earn between $460,000 and, at most, $1.1 million.
For weeks, controllers have been subtly rebelling, with more than 200 calling in sick. Inspectors found that most were not ill enough to stay home from work. Just last week in Barcelona, a quarter of the airport's controllers were no-shows for work.
José Luis Zoreda, of the travel industry's Exceltur, told the Guardian that 14 million tourists flew into Spain last July and August, spending roughly $19 million.