Nearly all flights at Berlin's two airports will be cancelled on Friday, a spokesman said, with ground staff set to start a 25-hour strike in the morning over a pay claim.
Germany's Verdi union gave notification of the strikes earlier on Thursday, stepping up action after several stoppages in recent weeks that have forced the cancellation of more than 300 flights.
Workers will walk out at 4am local time (0300 GMT) and end the strike at about 0400 GMT on Saturday, Verdi said.
"Even after the end of the strikes on Saturday, there can be restrictions, cancellations and delays throughout the day," a spokesman for Berlin's airport operator said by email.Berlin's two airports handle around 500 flights a day.
The stoppage, expected after 98.6 per cent of balloted workers at Schoenefeld and Tegel airports last week backed industrial action, coincides with the world's biggest tourism trade fair, which ends in Berlin on March 12.
The ITB fair attracted 120,000 trade visitors last year.Verdi wants an increase in pay for ground staff to 12 euros (S$18) an hour from about 11 euros as part of a one-year collective agreement.
Carriers including Air Berlin, Lufthansa, easyJet and Ryanair serve the two airports.
EasyJet said late on Thursday it needed to cancel 90 flights on Friday at Schoenefeld and was bracing for delays on other flights at the airport southeast of central Berlin.Ground staff jobs include checking in passengers, loading and unloading planes and directing aircraft on the tarmac.