In Berlin, all departures and 70 out of 240 incoming flights were canceled, German news agency dpa reported. Due to a walkout announced at short notice by trade union ver.di, the airport in Hamburg announced in the early morning that 31 of 160 departures had been canceled, AP reported.
The walkouts started at 3:30 am and were supposed to last until midnight.
The union wants to increase pressure on employers with whom it is negotiating bonuses for special working hours, for example at weekends, and rules on overtime pay.
The union has staged frequent walkouts over recent months to underline its demands, with local transport, hospitals and other public services hit.
On the weekend, German government officials and labor unions reached a pay deal for more than 2.5 million public-sector workers, ending a lengthy dispute and heading off the possibility of disruptive all-out strikes. That agreement did not include airport employees, however.