Strikes by German public sector workers and French airline staff have forced the cancellation of hundreds of flights in Europe as unions demand better pay.
The planned walkouts in Germany also affected public transport, nursery schools and municipal administrations.
The walkout has forced German airline Lufthansa to cancel some 800 flights and is expected to paralyse traffic in many of the country's western cities.
Affected airports include Frankfurt, which is Germany's biggest, as well as Munich, Cologne-Bonn and Bremen.
Three flights from Dublin Airport to Germany have been affected by the strike action today.
The ver.di union said Germany's healthy economy is filling public coffers with record tax income and public workers deserve a cut.
It wants a 6%, or at least €200 per month, pay rise for some 2.3 million public sector employees.
Workers who stand to gain include airport ground crews, bus drivers, hospital staff, daycare employees and other municipal employees.
Further strikes are planned in the coming days.
In France, a quarter of Air France flights were cancelled today as pilots, ground staff and others went on strike, also demanding a 6% pay rise after years of salary freezes.
It was the sixth such Air France strike since February, and unions plan further walkouts in the coming weeks alongside French train worker strikes over President Emmanuel Macron's economic reforms.
- Digital Desk and Press Association