Flight attendants of German carrier Lufthansa at Frankfurt Airport went on strike early on Tuesday, the cabin crew union Ufo said.
The action at Germany's busiest airport started at 4 am (0300 GMT) and was due to last until 11 pm, a union spokeswoman confirmed.
Some 600 flights were expected to be cancelled due to the industrial action, according to the national carrier, affecting 70,000 passengers.
Lufthansa cabin crew at Munich Airport were set to strike from 4 am to 11 pm on Wednesday. Lufthansa estimates that that strike would result in 400 flights being cancelled and some 50,000 passengers unable to take off.
At the weekend, Ufo had called on the approximately 19,000 flight attendants at German carrier Lufthansa and its subsidiary Lufthansa Cityline to go on strike.
More than 96% of cabin crew of the core company and at Lufthansa Cityline had previously voted for industrial action in separate strike ballots, Ufo said.
UFO is asking for a 15% increase in pay for flight assistants and also wants to achieve an inflation compensation bonus of €3,000 ($3,280).
This is one of several current wage disputes for Lufthansa. Last week, ground staff organized by another union, Verdi, paralyzed much of Lufthansa's passenger traffic with what was now their fifth wave of industrial action. Negotiations with Verdi are due to resume on Wednesday.
