The strike over working hours hit an estimated 300,000 passengers on a long holiday weekend, prompting the government to put the military in command of the skies and threaten prison for absent controllers.

Of 184 air traffic controllers scheduled to work, “practically the whole shift went to work,” said a spokesman for airport operator AENA, allowing flights to recommence.

Within hours take-offs and landings began at Madrid-Barajas, Barcelona-El Prat and other airports dotted around the country.

“We are going to try to re-establish the network first thing tomorrow,” said a spokesman for Spanish flag carrier Iberia, which had cancelled flights until 6:00 am (0500 GMT) Sunday.

Transport Minister Jose Blanco told Spanish media the airspace was completely open but it might take another 24 to 48 hours to recover normality as flights were rescheduled.

The Socialist government had declared the first state of alert since Spain turned into a democracy after the 1975 death of dictator General Francisco Franco.

Ministers at an emergency cabinet meeting agreed the extraordinary measure for 15 days because airports had been paralysed, Interior Minister Alfredo Perez Rubalcaba told reporters.

Air traffic control had been placed under the control of the military by Prime Minister Jose Luis Rodriguez Zapatero the previous evening after controllers called in sick en masse.

Under the state of alert, controllers were under the orders of the military and could be charged for disobeying an order under the military penal code, Rubalcaba said, warning of heavy prison sentences.

Striking air traffic controllers were defending “intolerable privileges” which the government would not accept, said the minister, who is also deputy prime minister.

According to the transport ministry, there are 2,300 air traffic controllers in Spain of whom 135 earn more than 600,000 euros a year and 713 between 360,000 and 540,000 euros a year.

In February the government cut back controllers’ overtime to a maximum 80 hours a year, slicing into paypackets that had bulged with overtime pay of two-three times the normal rate of 117 euros an hour.

The strike coincided with a government ruling Friday that the maximum time worked by air traffic controllers is 1,670 hours a year — 32 hours a week — but this excludes non-aeronautical work.

A spokesman for the Syndicate Union of Air Controllers said this meant time taken for paternity or sick leave would not count within the maximum working hours.

“We have reached our limit,” union spokesman Jorge Ontiveros said.

But they found little sympathy among stranded passengers strewn across the floor in yellow army blankets at Madrid airport.

Next Monday and Wednesday are days off in Spain and many people were also taking Tuesday off so as to have a five-day break.

“It is not right they should be demanding wage increases when there are so many people out of work, they are privileged,” said 31-year-old Nouria Sanchez waiting for her flight to Tenerife to be officially cancelled so she could demand a refund.

It was the gravest crisis in Spain’s skies since an Icelandic volcano erupted in April, forcing the world’s biggest shutdown since World War II with 100,000 flight cancellations in two months.

The strike was also a test for Spain’s government, which vowed to cut costs so as to calm fears of a Greek-style debt crisis, including by reforming airport work hours and partly privatising AENA.

As part of a package of measures the government said it would sell up to 49 percent of AENA, raising as much as nine billion euros according to Spanish media. Originally it planned to sell only 30 percent.