Air traffic controllers have gone on strike around Europe in protest at cost cuts and planned reforms.
Unions from 12 EU countries took part in the action.
They are angry at an EU proposal designed at reforming the way Europe’s airspace is governed.
Officials said it would increase competition and efficiency.
Terence Galea, president of Malta’s Air Traffic Controllers’ Association, rejected that idea: “They will force the companies providing that service to cost reduction. And that would mean also a risk to the provision of safe air traffic service. So in the end it will be a reduction in the safety in the skies.”
Europe’s skies see some nine million flights each year across more than 400 airports
Volker Dick, president of ATCEUC, which represent air traffic controllers across Europe, said: “We will lose around 10,000 working places. And this is for us, as a union, is certainly not acceptable. And what reason do we have to have to go on the streets if not this? “
Cancellations and delays are expected on Thursday.
Airlines advised passengers to check the status of their flights before traveling to the airport.