The security workers at Frankfurt went on strike at 2 am Friday (0100 GMT) and were to stay off the job until 11 pm in a warning strike to press their demands for an hourly wage of 16 euros (USD 22), the dpa news agency reported. Employers are offering between 10 to 13 euros per hour.
By mid-morning 41 flights had been cancelled and the airport reported long check-in lines.
Short-term strikes are a common practice in Germany for unions to put pressure on employers. The two sides are next scheduled to negotiate on March 5.