Spain's military took control of the nation's airspace on Friday night after air traffic controllers staged a massive walkout that stranded at least 330,000 travellers on the eve of a long holiday weekend, forcing the government to shut down Madrid's big international hub and seven other airports.
About six hours after the walkout started, causing total travel chaos, Deputy Prime Minister Alfredo Perez Rubalcaba announced that the Defence Ministry had "taken control of air traffic in all the national territory." He said the army would make all decisions on air traffic control, organisation, planning and supervision.
If enough controllers do not show up for work on Saturday to restore normal flight operations, the government will declare a national emergency that would force them to do so, Mr Rubalcaba said. No-show controllers will face unspecified criminal charges punishable by "serious prison time," he added.
Spanish flagship carrier Iberia said all of its flights in and out of Madrid were suspended until at least 11 am on Saturday, but other airlines did not give guidance for when flights might resume.
The controllers abandoned their posts amid a lengthy dispute over working conditions and after the administration of Prime Minister Jose Luis Rodriguez Zapatero on Friday approved a package of austerity measures - including a move to partially privatise airports and hand over management of Madrid and Barcelona airports to the private sector.
Angry passengers waited in huge lines for hours until giving up when it became clear their flights would not depart. Air traffic controllers meeting to plot strategy at a hotel near Madrid's airport were heckled and filmed by stranded passengers as the controllers entered.
Handfuls of passengers made it out of Madrid to destinations like Barcelona and Lisbon, Portugal, on buses provided by airlines. But the vast majority were forced to go home or to hotels with no information on when they might make their cancelled flights. Some slept in the airports.
"It's a disgrace, how can a group of people be so selfish as to wreck the plans of so many people?" said dentist Marcela Vega, 35, unable to travel from Madrid to Chile with her husband, five-year-old son and baby boy.
Spain's airport authority, known as Aena, said authorities were in contact with Europe's air traffic agency, Eurocontrol, and the United State's FAA about how best to deal with arriving international flights. Aena chief Juan Ignacio Lema called the wakout "intolerable" and warned controllers to return to work, or face disciplinary action or criminal charges.
Spain's air traffic controllers have been in bitter negotiations for a year with state-owned Aena over wages, working conditions and privileges. The dispute intensified in February after the government restricted overtime, cutting the average annual pay of controllers from about 350,000 euro (£297,600) to around 200,000 euro (£170,000).