Spanish airspace is open again after a wildcat strike by air traffic controllers ended on Saturday.
Civilian controllers called in sick en-masse on Friday afternoon at the start of a holiday weekend, in protest over their working hours.
Airports had been paralysed since then and the government declared a state of emergency.
Controllers are returning to work, but the government says it will take up to two days for air traffic to return to normal.
About 250,000 people have had their travel plans disrupted.
It is the first state of alert to be declared in Spain since the end of military rule in 1975, after the death of General Francisco Franco.