Air traffic controllers went on strike on Tuesday (May 11), as part of a general walk-out in Greece.
The strike, taking place between 12 noon and 4pm, resulted in disruptions and flight cancellations.
Another strike in the coming months has not been ruled out.
Greek carrier Aegean Airlines, for example, cancelled 24 domestic and four international flights, while it has been forced to change the departure time of 13 domestic and 26 international flights.
A statement on Athens International Airport said: “Due to participation of the air traffic control personnel in the 24-hour strike of the Supreme Administration of Greek Civil Servants Trade Unions on Wednesday, no flight will be realized from or to Athens International Airport from 12:00 until 16:00.”
Train and bus drivers also went on strike, cancelling a large number of today’s services.
The protests were over austerity measures imposed by the Greek government, in its bid to keep the debt-ridden country solvent.